Which species can you plant to increase the nutrients in your soil and boost biodiversity, and which pathogen tackles some of those pesky weeds? Our resident gardening expert, Professor Geoff Dixon, tells us more.
The term ‘sustainability’ for gardening means replacing what you take out of the soil and supporting localised biodiversity. Harvested crops, for example, take out nutrients and water from the soil. Replacements should be supplied that aid biodiversity and have minimal impact, or zero impact, on climate change.
Seaweed (Ascophyllum) has been recognised as a valuable fertiliser source in British coastal areas for centuries. Now, proprietary seaweed extracts are gaining popularity either when applied directly as liquid feeds or sprays, or when added into composts.
Classed as biostimulants, seaweed extracts contain several micro-nutrients and a range of valuable plant stimulatory growth regulators. They encourage pest and disease tolerance, increase frost tolerance, stimulate germination, increase robust growth, and add polish to fruit such as apples and pears.
Seaweed bolsters some of the nutrients lost through gardening. Image from Geoff Dixon.
Benefits of borage
Some plants are very effective supporters of biodiversity. Borage (Borago officinalis), known also as starflower or bugloss, is a robust annual plant of Mediterranean origin with pollinator-attractive blue flowers.
It is very drought resistant and suitable for dry gardens. Although an annual, it is self-seeding and could spread widely. It is very attractive to bees as it produces copious light – and delicately flavoured honey.
Its flowers and foliage are edible with a cucumber-like flavour, making it suitable in salads and as garnishes, while in Germany it is served as grűne soße (green sauce). When used as a companion plant for crops such as legumes or brassicas, it will also help to suppress weeds.
Borage is good for bee and belly. Image from Geoff Dixon.
Weeding out the problem
Weeds are a continuous problem for gardeners and their prevalence varies with the seasons. Groundsel (Senecio vulgaris), also known as ‘old man in the spring’, persists whatever the weather.
It is ephemeral but can seed and regrow several times per year. As a result, once established, it is difficult to control without very diligent hand weeding and hoeing out young seedlings before the flowers form.
There is, however, a form of biological control that can aid the gardener. Groundsel is susceptible to the fungal rust pathogen (Puccinia lagenophorae). This pathogen arrived in Great Britain from Australia in the early 1960s. Since then, it has become well established and outbreaks on groundsel start to become obvious in mid- to late-summer, especially in warm dry periods.
A fungal pathogen can kill groundsel, a weed that comes through several times a year. Image from Geoff Dixon.
Severe infections weaken, and eventually kill, groundsel plants. Gardeners should take advantage of the infection and remove the diseased weeds before any seeds are produced.
>> How else has climate change changed the way our gardens grow, and what can be done to alleviate its effects? Geoff Dixon investigates.
Professor Geoff Dixon is author of Garden practices and their science, published by Routledge 2019.
Written by Professor Geoff Dixon. You can find more of his work here.
The wild weather fluctuations wrought by climate change are stressing out our plants. Our resident gardening expert, Professor Geoff Dixon, explains how.
Pests and diseases are familiar causes of plant damage and loss. Less familiar, but becoming more frequent, are stresses resulting from environmental causes.
These are termed abiotic stresses because no living organism is involved. This means there are no visible signs of pests or pathogens. Diagnosis and treatment are, therefore, less straightforward. These causes are a result of interactions between the plant genotype and the prevailing or changing environment.
Damage may only become apparent after harvesting and at the point of consumer use. A typical example of this is internal browning or breakdown of Brussels sprouts. Larger sprouts are more susceptible to stress, with dense leaf packing in the bud, particularly in early and midseason cultivars.
The internal browning of Brussels sprouts is a consequence of plant stress.
A suggested cause is water condensing within the bud, which restricts calcium transport and leads to marginal leaf necrosis (death). This resembles the exudation, or perspiration, of water from leaf edges when growing plants absorb excessive water, flooding the vascular systems following very heavy rainfall and hot weather.
Oedema is another moisture-induced disorder. Symptoms include unattractive wart-like swellings coalescing on leaves and stems, particularly on Brussels sprouts, cabbages, and cauliflowers. These may rupture, becoming corky with a yellowish or brownish appearance.
Moisture-induced damage to cabbage leaves.
These symptoms result from high soil moisture content and high relative humidity associated with hot days and cool nights. Both internal browning and oedema can be minimised by improving soil structure, encouraging rapid drainage by deep cultivation or growing plants on raised beds.
Improving soil structure is becoming an important way to control salt accumulation. Soil structure can be badly damaged by flooding that brings in polluted water. In subsequent vegetable and fruit crops, plant water uptake, nutrient use efficiency, and photosynthesis are all impaired. The effects are seen in poor germination, burnt leaf margin, stunting, and wilting. This damage will be particularly severe with highly organic soils.
Salt accumulation in onion crops. Improving soil structure is one way of addressing this problem.
Abiotic disorders are becoming more common in commercial crops and this is likely to be reflected in gardens and allotments. That is an effect of climatic change, with generally hotter and wetter conditions interspersed by droughts and freezing events.
As a result, plant growth is erratic and exhibits abiotic disorders. Plant breeders, especially in Asia, are actively seeking genetic solutions that will create crops capable of withstanding erratic environments. In parallel,the agro-chemical industry is producing environmentally sustainable compounds and biostimulants to help combat these problems.
>> How else has climate change changed the way our gardens grow, and what can be done to alleviate its effects? Geoff Dixon explored this issue further.
Professor Geoff Dixon is author of Garden practices and their science, published by Routledge 2019.
How do flowers use fragrance to attract pollinators, and how do pollution and climate change hamper pollination? Professor Geoff Dixon tells us more.
‘Fragrance is the music of flowers’, said Eleanour Sophy Sinclair Rohde, an eminent mid 20th century horticulturist. But they are much more than that. Scents have fundamental biological purposes. Evolution has refined them as means for attracting pollinators and perpetuating the particular plant species emitting these scents.
There are complex biological networks connecting the scent producers and attracted pollinators within the prevailing environment. Plants flowering early in the year are generalist attractors. By late spring and early summer, scents attract more specialist pollinators as shown by studies of alpines growing in the USA Rocky Mountains. This is because there is a bigger diversity of pollinator activity as seasons advance. Scents are mixtures of volatile organic compounds with a prevalence of monoterpenes.
Environmental factors will affect scent emission. Natural drought, for example, changes flower development and reduces the volumes and intensity of scent production. The effectiveness of pollinating insects, such as bees, moths, hoverflies and butterflies is reduced by aerial pollution.
Pheasant’s eye daffodils (Narcissus recurvus).
Studies showed there were 70% fewer pollinators in fields affected by diesel fumes, resulting in lower seed production. Pollinating insects do not find the flowers because nitrogenous oxides and ozone change the composition of scent molecules.
Extensive studies of changes in flowering dates show that climate change can severely damage scent–pollinator ecologies. Over the past 30 years, blooming of spring flowers has advanced by at least four weeks. Earlier flowering disrupts the evolved natural synchrony between scent emitters and insect activity and their breeding cycles. In turn that breaks the reproductive cycles of early flowering wild herbs, shrubs and trees, eventually leading to their extinction.
The lilac bush, known for its evocative scent.
Scents provide powerful mental and physical benefits for humankind. Pleasures are particularly valuable for those with disabilities especially those with impaired vision. Even modest gardens can provide scented pleasures.
Bulbs such as Pheasant’s eye daffodils (Narcissus recurvus) (illustration no 1), which flower in mid to late-spring, and lilacs (illustration no 2) are very rewarding scent sources.
Sweetly perfumed annuals such as mignonette, night-scented stocks, candytuft and sweet peas (illustration no 3) are easily grown from garden centre modules, providing pleasures until the first frosts.
Sweet peas are easily grown from garden centre modules.
Roses are, of course, the doyenne of garden scents. Currently, Harlow Carr’s scented garden, near Harrogate, highlights the cultivars Gertrude Jekyll, Lady Emma Hamilton and Saint Cecilia as particularly effective sources of perfume. For larger gardens, lime or linden trees (Tilia spp) form profuse greenish-white blossoms in mid-season, laden with scents that bees adore.
Written by Professor Geoff Dixon, author of Garden practices and their science, published by Routledge 2019.
How much soil cultivation do you need for your vegetables? Professor Geoff Dixon explains all.
Cultivating soil is as old as horticulture itself. Basically, three processes have evolved over time. Primary cultivation involves inversion which buries weeds, adds organic matter and breaks up the soil profile, encouraging aeration and avoiding waterlogging.
Secondary cultivation prepares a fine tilth as a bed for sowing small seeded crops such as carrots or beetroot. In the growing season, tertiary cultivation maintains weed control, preventing competition for resources (illustration no. 1) such as light, nutrients and water while discouraging pest and disease damage.
Lettuce and seed competition
The onset of rapid climate change encouraged by industrialisation has focused attention on preventing the release of carbon dioxide into the atmosphere. Ploughing disturbs the soil profile and accelerates the loss of carbon dioxide from soil.
It is also an energy intensive process. Consequently, many broad acre agricultural crops such as cereals, oilseed rape and sugar beet are now drilled directly without previous primary cultivation. An added advantage is that stubble from previous crops remains in situ over winter, offering food sources for birds. The disadvantages of direct drilling are: increased likelihood of soil waterlogging and reduced opportunities for building organic fertility by adding farmyard manure or well-made composts.
Overall, primary and secondary cultivation benefit vegetable growing. The areas of land involved are far smaller and the crops are grown very intensively. Vegetables require high fertility, weed-free soil, good drainage and minimal accumulation of soil-borne pests and diseases.
Frost action breaking down soil clods
Digging increases each of these benefits and provides healthy physical exercise and mental stimulation. Frost action on well-dug soil breaks down the clods (illustration no. 2). Ultimately, fine seed beds are produced by secondary cultivation (illustration no. 3), which encourage rapid germination and even growth of root and salad crops.
Tertiary cultivation to prevent weed competition is also of paramount importance for vegetable crops. Competition in their early growth stages weakens the quality of root and leafy vegetables, destroying much of their dietary value. Regular hoeing and hand removal of weeds are necessities in the vegetable garden.
Raking down soil producing a fine tilth
Ornamental and fruit gardens similarly benefit from tertiary cultivation. Weeds not only provide competition but are also unsightly, destroying the visual image and psychological satisfaction of these areas.
Lightly forking over these areas in spring and autumn encourages water percolation and root aeration. Once established, ornamental herbaceous perennials and soft and top fruit areas benefit greatly from the addition of organic top dressings. Over several seasons these will augment fertility and nutrient availability.
Written by Professor Geoff Dixon, author of Garden practices and their science, published by Routledge 2019.
A sprig of thyme to fight that cold… Turmeric tea after exercising… An infusion of chamomile to ease the mind… As we move with fresh resolution through January, Dr Vivien Rolfe, of Pukka Herbs, explains how a few readily available herbs could boost your health and wellbeing.
The New Year is a time when many of us become more health conscious. Our bodies have been through so much over the last few years with Covid, and some of us may need help to combat the January blues. So, can herbs and spices give us added support and help us get the new year off to a flying start?
The oils in chamomile have nerve calming effects.
We may wish to ease ourselves into the year and look for herbs to help us relax. The flowers from these herbs contain aromatic essential oils such as linalool from lavender (Lavandula) and chamazulene from German chamomile (Matricaria recutita) that soothe us when we inhale them (López et al 2017). Chamomile also contains flavonoids that are helpful when ingested (McKay & Blumberg 2006).
If you have a spot to grow chamomile in your garden, you can collect and dry the flowers for winter use. Lavender is also a staple in every garden and the flowers can be dried and stored. Fresh or dry, these herbs can be steeped in hot water to make an infusion or tea and enjoyed. As López suggests, the oils exert nerve calming effects. Maybe combine a tea with some breathing exercises to relax yourselves before bed or during stressful moments in the day.
Thyme is a handy herbal remedy. Generally, the term herb refers to the stem, leaf and flower parts, and spice refers to roots and seeds.
>> The plant burgers are coming. Read here about the massive growth of meat alternatives.
Many people may experience seasonal colds throughout the winter months and there are different herbal approaches to fighting infection. Andrographis paniculata is used in Indian and traditional Chinese medicine and contains bitter-tasting andrographolides, and in a systematic review of products, the herb was shown to relieve cough and sore throats symptoms in upper respiratory tract infection (Hu et al 2017).
Gargling with herbal teas is another way to relieve a sore throat, and the benefits of green tea (Camellia sinensis) have been explored (Ide et al 2016). I’m an advocate of garden thyme (Thymus vulgaris) which contains the essential oil thymol and is used traditionally to loosen mucus alongside its other cold-fighting properties.
You could experiment by combining thyme with honey to make a winter brew. I usually take a herbal preparation at the sign of the very first sneeze that hopefully then stops the infection progressing.
Shatavari (pictured) is said to improve strength, and ashwagandha can help recovery.
We may start the new year with more of a spring in our step and wishing to get a little fitter. As we get older, we may lose muscle tissue which weakens our bones and reduces our exercise capability. Human studies have found that daily supplementation with shatavari (Asparagus racemosus) can improve strength in older women, and ashwagandha (Withania somnifera) can enhance muscle strength and recovery in younger males (O’Leary et al 2021; Wankhede et al 2015).
These herbs are known as adaptogens and traditionally they are used in tonics or to support fertility. The research to fully understand their adaptogenic activity or effects on muscle function is at an early stage. Other herbs such as turmeric may help muscle recovery after exercise. I brew a turmeric tea and put it in my water bottle when I go to the gym.
>> How is climate change affecting your garden? Find out here.
Lemon balm is easy to grow but might want to take over your garden.
Depending on your resolutions, you could use herbs and spices to add lovely flavours to food to try and reduce your sugar and salt intake. Liquorice is a natural sweetener, and black pepper and other herbs and spices can replace salt.
You could also bring joy to January by growing herbs from seed on a windowsill or in a garden or community space. Mint, lemon balm, lavender, thyme, and sage are all easy to grow, although mint and balm may take over!
All make lovely teas or can be dried and stored for use, and research is also showing that connecting with nature – even plants in our homes – is good for us.
You can read more about medicinal and culinary properties of herbs at https://www.jekkas.com/.
If you wish to learn more about the practice of herbal medicine and the supporting science, go to https://www.herbalreality.com/.
>> Dr Viv Rolfe is head of herbal research at Pukka Herbs Ltd. You can find out more about Pukka’s research at https://www.pukkaherbs.com/us/en/wellbeing-articles/introducing-pukkas-herbal-research.html, and you can follow her and Pukka on Twitter @vivienrolfe, @PukkaHerbs.
Edited by Eoin Redahan. You can find more of his work here.
Gardens in December should, provided the weather allows, be hives of activity and interest. Many trees and shrubs, especially Roseaceous types, offer food supplies especially for migrating birds.
Cotoneaster (see image below) provides copious fruit for migrating redwings and waxwings as well as resident blackbirds. This is a widely spread genus, coming from Asia, Europe and northern Africa.
Cultivated as a hedge, it forms thick, dense, semi-evergreen growth that soaks up air pollution. In late spring, its white flowers are nectar plants for brimstone and red admiral butterflies and larval food for moths. Children and pets, however, should be guided away from the attractive red berries.
Cotonester franchetti | Image credit: Professor Geoff Dixon.
Medlars (Mespilus germanica) offer the last fruit harvest of the season (see image below). These small trees produce hard, round, brownish fruit that require frosting to encourage softening (bletting).
Its soft fruit can be scooped out and eaten raw and the taste is not dissimilar to dates. Alternatively, medlar fruit can be baked or roasted and, when turned into jams and jellies, they are delicious, especially spread on warm scones.
Like most rosaceous fruit, medlars are nutritionally very rich in amino acids, tannins, carotene, vitamins C and B and several beneficial minerals. As rich sources of antioxidants medlars also help reduce the risks of atherosclerosis and diabetes.
Medlar fruit (Mespilus germanica) can be turned into jams and jellies | Image credit: Professor Geoff Dixon.
Garden work continues through December. It is a time for removing dead leaves and stems from herbaceous perennials, lightly forking through the top soil and adding granular fertilisers with high potassium and phosphate content.
Top fruit trees gain from winter pruning, which opens out their structure, allowing air circulation when fully laden with leaves, flowers and fruit. Fertiliser will feed and encourage fresh root formation as spring progresses.
The vegetable garden is best served by digging and incorporating farm yard manure or well-rotted compost, which adds fertility and encourages worm populations. The process of digging is also a highly beneficial exercise for the gardener (see illustration no 3).
Turning the soil isn’t only good for your garden - it boosts your wellbeing | Image credit: Professor Geoff Dixon.
Developing a rhythm with this task supports healthy blood circulation and, psychologically, provides huge mental satisfaction in seeing a weedy plot transformed into rows of well-turned bare earth.
When the weather turns wet, windy and wintery it provides opportunities for cleaning, oiling and sharpening tools, inspecting stored fruit and the roots of dahlias kept in frost-proof conditions.
Finally, there is always the very relaxing and pleasant task of reading through seed and plant catalogues and planning what may be grown in the coming seasons.
Written by Professor Geoff Dixon, author of Garden practices and their science, published by Routledge 2019.
How has climate change changed the way our gardens grow and what can be done to alleviate its effects? Professor Geoff Dixon tells us more.
Climate has changed on Earth ever since it solidified and organic life first emerged. Indeed, the first photosynthesising microbes changed the atmosphere from carbon dioxide rich to oxygen rich over millions of years. What we now face is very rapid changes brought about by a single organism, mankind, through industrialisation.
The effects of change are very evident in gardens. Over a generation, leaf bud breaking and flowering by early spring bulbs, herbaceous plants, shrubs and trees has advanced by at least four weeks (see main image of Cyclamen hederifolium).
Latter spring displays have advanced by at least two weeks. This is caused by milder, wetter winter weather, encouraging growth. The danger lies in the increasing frequency of short sharp spells of severe frost and snow. These kill off precocious flowers and leaves which trees especially cannot replace.
Desiccated, cracked soil.
Increasingly, the summer climate is becoming hotter and drier. Since the Millennium there has been a succession of hot droughts. These seriously limit scope for growing vegetables, fruit and ornamentals unless irrigation is regularly available. Drought also damages soil structure especially where there is a high clay content by causing cracking and the loss of plant cover (see image of desiccated, cracked soil above).
Cracking disrupts and destroys the root systems of trees and shrubs in particular. The effects of root damage may not become evident until these plants die in the following years.
Climate change is apparently advantageous for microbes. Detailed surveys show that fungal life cycles are speeding up, increasing the opportunities for diseases to cause damage. Even normally quite resilient crops such as quince are being invaded during milder, damper autumns (See image of brown rot on quince fruit below). Throughout gardens, the range and aggressiveness of pests and disease is increasing.
Brown rot (Monilia laxa) on quince fruit.
However, each individual garden or allotment, no matter its size, can contribute to reducing the rate of climate change. Simple actions include the removal of hard landscaping, and planting trees and shrubs reduces carbon emissions.
Using electric-powered tools and machinery in place of petrol or diesel has similar advantages. Tumbling down parts of a garden into native flora, and perhaps encouraging rarer plants such as wild orchids or fritillarias, mitigates climate change. Such areas may also form habitats for hedgehogs or slow worms, increase populations of bees, butterflies and moths and encourage bird life.
All images from Professor Geoff Dixon.
Lilies provide gloriously beautiful and well scented flowering border plants. Choose flowering size bulbs in the garden centre or from a catalogue. Grow these through the winter potted in a general garden compost placed in an unheated greenhouse or cold frame. By March or early-April, substantial green shoots will have formed from the bulbs and they can be transplanted into the garden.
Lilies need a sunny border and very fertile soil to encourage vigorous root growth capable of supporting the flowering spike and ancillary bulbs as they are initiated. This produces magnificent flowers and an increasing colony of bulbs that will spread and become established over future seasons.
Lilium longiflorum, often called the Easter lily | Image credit: Professor Geoff Dixon.
Regular watering and feeding with nutrients are needed, especially potassium, which encourages root and shoot growth. Stake the flower spike as it grows, giving support for the flowers because they are heavy when fully open and easily damaged by winds.
Rewards come in mid-summer with magnificent colourful flowers and wonderful perfumes on warm evenings. Apart from severe winters, lilies are hardy garden plants unless they are from groups specified as tender and requiring protection. In the autumn, simply cut down the flowering spike and remove any fallen foliage.
Buds developed on lily scales after culturing | Image credit: Professor Geoff Dixon.
The Lilium genus has about 100 species originating worldwide mainly from north temperate areas of Europe, Asia and America. The colour range includes white, yellow, orange, pink, red and purple. Plant breeders in The Netherlands, Japan and North America have produced a huge range of multi-coloured hybrids.
Taxonomically, Lilium is divided into divisions, of which the Turk’s Caps, Martagons and American hybrids are popular. The most destructive pest is the scarlet lily beetle (Lilioceris lilii) which devours foliage, flowers and bulbs. The first signs of trouble are shot holes in the foliage. Picking off beetles and larvae is an effective means of dealing with low-level infestations.
Comparison of lily bulbils growing from scale leaves, immature bulb and flowering size bulb | Image credit: Professor Geoff Dixon.
Asexual propagation is a simple and enjoyable occupation. Divide a good-sized bulb into its scales. Choose healthy scales from the outer rings and place these in a plastic box containing damp kitchen paper and place in an airing cupboard. After about 10-12 weeks, small bulbils will have formed on each scale.
Select the boldest mother scales and bulbils and plant in a tray of seedling compost and grow in the greenhouse. After two or three months the most vigorous young plants can be potted individually. Eventually these are planted in the garden and will develop into flowering size bulbs after two or three years.
Main image: Pea crop | Image credit: Geoff Dixon
Peas are a very rewarding garden crop. Husbandry is very straightforward, producing nutritious yields and encouraging soil health by building nitrogen reserves for future crops.
Rotations usually sequence cabbages and other nitrogen-demanding crops after peas. This is a sustainable way to use the organic nitrogen reserves left by pea roots resulting from their mutually beneficial association with benign bacteria. These microbes capture atmospheric nitrogen, producing ammonia, nitrites and nitrates in a sequence of natural steps.
Peas originated in the Mediterranean. They were cultivated continuously by ancient civilisations and through medieval times, and are now the seventh most popular vegetable.
Illustration 1: Pea seeds | Image credit: Geoff Dixon
In bygone centuries, peas provided a protein source for the general population as cooked meals of pea soup and pease pudding helped keep famine at bay before the introduction of potatoes. In the 18th century, French gardeners working for the aristocracy produced fresh peas using raised and protected beds of fermenting animal manure. The composting processes produced heat and released carbon dioxide, stimulating rapid growth.
Generally, however, eating fresh peas only gained popularity in the 20th century as canned and then quick-frozen foods were invented, and large-scale technological development enabled mechanised and automated commercial precision cropping. In recent times, retail market demand has returned for unshelled podded peas – a manually picked crop known colloquially as ‘pulling peas’.
Seeds can be sown directly (illustration 1) or transplants (illustration 2) can be raised under protection, giving an early boost for growth and maturity. Peas are cool season crops. They grow best at 13-18°C and mature about 60 days after sowing.
Illustration 2: Pea seedlings | Image credit: Geoff Dixon
Some cultivars such as Meteor can be grown over winter, preferably protected with cloches for very early cropping. The spring sown The Sutton cultivar group (CV) gives rapid but modest returns, and main crop CVs, such as Hurst Green Shaft, deliver the heaviest returns (illustration 2). This cultivar forms several long, well-filled pods at the fruiting nodes.
Sugar peas or mange tout – where the entire immature pod is eaten – is a popular fresh crop, while quick-growing pea shoots that mature in 20 days from sowing are excellent additions for salads or as garnishes for warm cuisine.
Human health benefits significantly by including peas in the diet. As well as being an excellent protein source, they produce a range of vitamins and nutrient elements. Their coumestrol content aids the control of blood sugar levels, helping combat diabetes, heart diseases and arthritis.
So, it’s certainly worth finding a spot for this versatile vegetable in your garden.
Written by Professor Geoff Dixon, author of Garden practices and their science.
The iris family (Iridaceae) provides gardeners with a glorious array of colourful and frequently well scented flowers. Originating from both tropical and temperate regions, some such as freesias are best cultivated under protection. Others such as gladioli and crocus are reliable garden plants.
Iris, or fleur-de-lis, is one of the larger genera, offering colour and interest from the very earliest springtime through to May and June. The earliest and always most welcome is Iris unguicularis (previously Iris stylosa). Flowers (see illustration 1) emerge in the darkest days of December, encouraged by the warming effects of climate change.
Illustration 1: Iris unguicularis (syn Iris stylosa) / Image credit: Geoff Dixon
Originating from North Africa, it thrives in south facing dry borders, preferably under a wall where winter sunshine encourages proliferous flowering. Every few years, lift and divide the clump of small rhizomes after flowering has finished. Remove older growth and replant younger roots with a modest handful of compost and water well. Established clumps can be cut back, removing dead leaves during late spring.
By contrast Iris pseudacorus, the water flag, thrives in wet, boggy places or even when immersed in water. Found across Europe, it is a British native plant producing vivid yellow flowers that are rich sources of nectar. In parts of Scotland it forms large expanses of natural growth that are favoured by nesting corncrakes. It can be cultivated as part of water purification programmes since nitrogen and phosphorus are extracted by the vigorous root systems.
Illustration 2: Iris germanica / Image credit: Geoff Dixon
The prima donna is Iris germanica, the flag or bearded iris. These are stately plants, producing flower spikes up to one metre high and furnished with multicoloured flowers (illustration 2). Upright standard petals can contrast completely with the falls which bear a beard of yellow pollen bearing stamens. Fertiliser should be applied as the flower spikes appear. It should be applied again after flowering, stimulating root growth in anticipation of a colourful display in the next season.
Illustration 3: Rhizome ready for division / Image credit: Geoff Dixon
The rhizome is a large swollen ground-creeping stem from which side shoots develop with a terminal area of older tissue (illustration 3). Every four or five years, the rhizomes should be lifted and divided by removing the terminal tissue and splitting off side shoots with a sharp knife. These and the main rhizome should be replanted carefully, ensuring that they rest on the soil surface with their fibrous roots buried beneath them. Multiplication eventually provides a border filled with very colourful displays that can persist for a month since flowers frequently emerge along most of the spike.
Perennial bush soft fruits are among the crown jewels of gardening. Gooseberries, red currants and blackcurrants when well established will annually reward with crops of very tasty ripe fruit which provide exceptional health benefits. These bushes will mature into quite sizeable plants so only relatively few, maybe one to five of each will be sufficient for most home gardeners or allotment owners.
Header image: Gooseberries | Image credit: Geoff Dixon
The art of successful establishment lies in initial care and planting. Buy good quality dormant plants from reputable nurseries or garden centres. Plunge the roots deeply in a bucket of water and plant as quickly as possible. These crops need rich fertile soil which is weed free and has recently been dug over with the incorporation of farmyard manure or well-rotted compost. Each bush requires ample growing space with at least a one metre distance within and between rows.
Take out a deep planting hole and soak with water. Place the new bush into the hole, spreading out the root system in all directions. Add mycorrhizal powder around and over the roots, which encourages growth promoting fungi. These colonise the roots, aiding nutrient uptake and protecting from soil borne pathogens. Carefully fold the soil back around the roots, shaking the plant. That settles soil in and around the roots and up to the collar which shows where the plant had grown in the nursery. Tread around the collar to firm the plant and add more water. Normally, planting is completed in late winter to early spring before growth commences.
Redcurrants | Image credit: Geoff Dixon
As buds open in spring, keep the plants well-watered. It is crucially important that the young bushes do not suffer drought stress, especially during the first summer. Supplement watering with occasional applications of liquid feed which contains large concentrations of potassium and phosphate plus micro nutrients. Remove all weeds and flowers in this first year. That concentrates all the products of photosynthesis into root, shoot and leaf formation for future seasons. Clean up around the plants in autumn, removing dead leaves that might harbour disease-causing pathogens.
These plants will flower and fruit from the first establishment year. Each bush will produce fruit which is a succulent and rewarding source of health-promoting vitamins and nutrients.
Blackcurrants | Image credit: Geoff Dixon
Blackcurrants are a fine source of vitamin C and have twice the antioxidant content of blueberries. Redcurrants are sources of flavonoids and vitamin B, while gooseberries are rich in dietary fibre, copper, manganese potassium and vitamins C, B5 and B6.
Blackbirds also like these fruits so netting or cages are needed! Continuing careful husbandry will yield a succession of expanding and rewarding crops.
Variously known as zucchini, courgette, baby marrows and summer squash, this frost tender crop is a valuable addition for gardens and allotments. Originating in warm temperate America, the true zucchini was developed by Milanese gardeners in the 19th century and popularised in the UK by travellers in Italy. It quickly matures in 45 to 50 days from planting out in open ground by early May in the south and a couple of weeks later farther north.
Alternatively, use cloches as frost protection for early crops. Earliness is also achieved by sowing seed in pots of openly draining compost by mid-April in a greenhouse or cold frame. Courgettes have large, energy-filled seeds. Consequently, germination and subsequent growth are rapid.
Sow seed singly in 10cm diameter pots and plant out when the first 2-3 leaves are expanding (illustration number 1). Alternatively, garden centres supply transplants. These should be inspected carefully, avoiding those with yellowing leaves or wilting foliage. Each plant should have white healthy-looking roots without browning.
Illustration 1: Courgette seedlings germinated in a greenhouse.
Courgettes grow vigorously and each plant should be allocated at least 1 metre spacing within and between rows. They require copious watering and feeding with a balanced fertiliser containing equal quantities of nitrogen, phosphorus and potassium.
Botanically, they are dioecious plants, having separate male and female flowers, (illustration number 2). They are beloved by bees, hence supporting biodiversity in the garden. Slugs are their main pest, causing browsing wounds on courgette fruits; mature late-season foliage is usually infected by powdery mildew fungi that cause little harm.
Illustration 2: Bee-friendly (and tasty) courgette flower.
Quick maturing succulent courgettes are hybrid cultivars, producing harvestable 15-25 cm long fruit (berries) before the seeds begin forming (illustration number 3). Harvest regularly at weekly intervals before the skins (epicarps) begin strengthening and toughening. Skin colour varies with different cultivars from deep green to golden yellow. The choice rests on gardeners’ preferences.
Courgettes are classed and cooked as vegetables and their dietary value is retained by steaming thinly sliced fruits. Courgettes are a low-energy food but contain useful amounts of folate, potassium and vitamin A (retinol). The latter boosts immune systems, helping defend against illness and infection and increasing respiratory efficiency. Eyesight is also protected by increasing vision in low light.
Illustration 3: Courgette fruit ready for the table.
Courgettes are, therefore, valuable dietary additions year-round. Courgette flowers are bonuses, used as garnishes or dipped in batter as fritters or tempura. Overall, the courgette is a most useful plant that provides successional cropping using ground vacated by over-wintered vegetables such as cabbage, Brussels sprouts or leeks.