News, Advice, Tips and Jobs For May
News, Advice, Tips and Jobs For May
After five weeks of lock down it is very hard to predict what will happen in the garden world in the next month. One thing is very certain, we are missing our garden centres, especially for our plants and sundries and while some garden centres and nurseries in our area have magnificently adapted to the current restrictions many gardeners are unable to get their basic requirements. It seems very unfair as of the 28th of April that B & Q now have over one hundred and fifty open including being able to sell plants while garden centres are still closed.
Both Alan Titchmarsh and Peter Seabrook have made very compelling and passionate pleas for them to reopen as of today that is still not possible. What is most worrying is that if nurseries cannot move existing crops then plants will have to be dumped with huge financial implications? It seems big businesses have the power to engage and get results while our gardening bodies despite huge efforts, seem powerless to get parity and a level playing field with DIY stores. We must stress garden centres do not expect to open restaurants and other non-garden sections, just be allowed to sell plants that would be otherwise dumped. Finally, today the rain arrived after weeks without rain many areas are now really short of water making gardening difficult, however the next 14 days look as though we will be getting sufficient to make it possible to resume good horticultural practices.
It is also the month when the Royal Horticultural Society normally stages its annual flower show at Chelsea but this year, we are to be entertained by visits to the desgners own gardens. For me however it is all the new plants and products I will be missing and worried about the effect on the nurseries and product people. With all flower shows cancelled for some time many nurseries have turned to online sales such as The Cactus couple and others have massively increased online sales such as Ashwood Nurseries and Surreal Succulents. Unfortunately, some have run in to difficulties due to the huge demand with sites crashing or being taken down as they cannot meet the huge increase in orders. Sadly, a few scoundrels have taken to the net to rip us off with people allegedly reselling seeds from Kings at vastly increased prices and here I would advise you to order directly from Kings Seeds. Regrettably I am hearing of poor plants, delays in delivery and unanswered phones from some of the other retail seed companies, after this is over I have a feeling we will remember who gave outstanding service and even more importantly those who either ripped us off or simply failed to deliver.
This month usually brings even the most reluctant gardeners out of doors, but it will probably include many first time gardeners, hence my list of jobs for each month. Most trees are now in full leaf, azaleas and rhododendrons in bloom and many spring-flowering bulbs and plants are still at their best.
During May we can expect all kinds of weather: thunderstorms, hail, snow on high ground, drying north westerly winds and glorious warm sunny days. Sometimes the sun is so bright it is tempting to believe that summer has arrived, but it is a mistake to be too hasty in planting out half-hardy and tender plants. Late May frosts are the bane of all gardeners. There is still a marked difference in the weather and conditions experienced in the north and south. The last frost here in our garden in south Birmingham was -2.8c at 05.29am on 26th March 2020.
Collect and conserve rainwater for use around the garden and in greenhouses and conservatories. Be prepared for a late spring frost, have horticultural fleece handy just in case.
The Ornamental Garden
Deadhead Tulips and Narcissi. Apply a feed to most garden bulbs.
Take cuttings using the young stems of herbaceous plants Get plant supports ready for the taller and floppier herbaceous plants as they put on rapid growth this month.
Weeds will be coming through in abundance as the weather warms and it important to tackle them at the first opportunity by hoeing when the weather is sunny and the soil dry. Paths and patios can be treated with a residual weed killer to prevent weed growth but remember to read the label and observe all instructions. Alternatively use a gas-powered burner or weed wand.
Check ornamentals for pests such as vine weevil, subjects in pots can be repotted into fresh compost. Slugs are likely to be a problem this month after the long dry spell, use an appropriate method of your choice.
Providing the weather is cool and damp there is still time to lift and divide clumps of herbaceous, especially those that flower from mid-summer onwards as they have time to establish first. I have successfully lifted and divided larger clumps of Hostas at this time of year, water well before lifting and after planting and protect from slugs.
Any further plantings of conifers and other evergreens should be speeded-up and finished as soon as possible this month. They will need plenty of water and some protection from drying winds. You should also complete the pruning of established evergreens, where necessary, in the very early part of the month and give formal hedges their first light trim, but avoid cutting into the older wood.
Berberis hedges should be trimmed once they have finished flowering (and you have checked there are no nesting birds)and other spring-flowering shrubs such as lilac and forsythia can be pruned as the flowers fade by removing complete branches rather than shortening back shoots that only serves to make for long vigorous shoots.
Hardy fuchsias could be planted later this month, but they will require a sheltered position. It is best to purchase larger specimens and to plant them slightly deeper than they were growing in their containers for added winter protection. On established hardy fuchsias, the dead wood should be pruned away now, and the plants trimmed to shape before feeding and top-dressing.
Early flowering rhododendrons may be ready for deadheading. They too will appreciate a light feed and top-dressing. Camellias can be trimmed back where it is necessary to remove dead wood or weak, straggly growth and shears used to remove old flower stems from heathers which have flowered since last summer. Then top-dress with organic matter and layer branches to encourage the development of new plants. Container-grown heathers can be planted now.
Suckering plants, such as roses and lilacs, should be checked over and any suckers pulled - not cut - from the rootstock. With the increasing risk of pests and diseases this month, you might consider spraying roses every three weeks as a precautionary measure. My Roses are regularly sprayed against Blackspot before it appears as fungicides are best applied as a prevention rather than a control. Tie in any long growths on climbing and rambler roses.
When flowering is finished, thin out Clematis montana, cutting back some of the older wood and then feeding and mulching. The same applies to Clematis alpina and C. macropetala. Tie in the shoots of other fast-growing climbers and keep on eye open for slugs and earwigs. Tie in new growths on later flowering clematis before they become damaged, especially by high winds or heavy rain.
Viburnum beetle along with Rosemary and lily beetle can be seen this month and are best culturally controlled by crushing,
alternatively Grazers Lily Beetle control which stops the beetle feeding and promotes more healthy growth can be recommended.
Thin out the shoots on established herbaceous plants and stake when necessary. They will also need feeding and mulching and steps should be taken to control slugs. Hollyhocks can be sprayed to prevent rust. Make sure that new planting of herbaceous subjects do not dry out.
Dahlia tubers can usually be safely planted in the garden from early May. Dahlia plants can be hardened off for planting out in late May or early June in well-prepared ground, staked and tied. Summer and early autumn-flowering chrysanthemums can also be planted now. They need a humus enriched soil. Pot-on late flowering chrysanthemums into 8in pots and transfer to a standing ground before spraying to control pests.
As bulbs finish flowering, the dead heads should be picked off. Daffodil and tulip bulbs can be removed to a shady spot in the garden and given a foliar spray to promote large bulbs for flowering next spring. Over-crowded clumps of daffodils can be marked for divion once the foliage has died down.
Summer bulbs, such as agapanthus, criniums, eremurus and lilies, will also be ready for a feed and top-dressing while tall lilies need staking. Pot-grown lilies should be hardened-off ready for planting later in the season.
Dead flowers should be removed from dwarf and immediate irises and now is the time to tie or push back the foliage of Iris unguicularis so that the sun can reach the roots. Remember to order bearded irises, ready for planting in July and August. You might consider planting nerines now. They should be set 4ins deep, in a sunny, sheltered spot, preferably against a south-facing wall.
Sweet peas should be watered when necessary and kept weed-free. For good-sized blooms it is important to pinch out the side shoots and tendrils.
Spring bedding can be cleared away as soon as practical and the ground prepared for summer planting. Lift divide and replant polyanthus and primroses when most of the flowers have faded and, in order to prolong flowering, continue removing the dead heads from pansies and violas.
Thin out any earlier sowings of hardy annuals preferably when the ground is moist and before seedlings are too large.
As soon as conditions permit, more hardy annuals can be sown in their flowering positions. Suitable subjects include Calendulas, candyturf, Convolvulus, Coreopsis, cornflowers, Dimorphotheca, Echium, Eschscholzia, Godetia, Helichrysum, Lavatera, Linaria, Linum, Nigella, poppies, Sscabious and sunflowers.
Half-hardy annuals raised under glass earlier in the spring should be gradually hardened-off and, weather permitting, can be planted out in milder areas. Complete the planting of hanging baskets for a good display in summer.
Continue carefully weeding the rock garden, leaving seedlings of more desirable plants if required. Gaps should be filled in with new alpine plants and you might consider designing and constructing new water features here or elsewhere in the garden. Trim back early spring subjects such as Aubrieta and Alyssum after they have finished flowering to encourage compact fresh growth for next year. Remove any old unwanted foliage that may be detrimental to the plant while providing a haven for pests. Aline beds may be top dressed with a gritty alpine mix.
Existing ponds also require attention. Clumps of overgrown waterlilies can be divided and replanted into baskets of loam with a covering of pebbles. Watch out for snail eggs on the underside of waterlilies and remove them to avoid over-population. Floating and marginal plants, as well as submerged oxygenators, should also be divided now. Any duckweed or blanket weed should be removed as soon as seen. Leave any weed removed by the pool side for insects, water snails and any other pondlife to escape back to the pond or pool.
Any containers with long term planting should be fed and watered as needed to keep plants healthy and growing. I also like to remove some old compost and add some fresh along with Osmocote type slow release fertilizer. During the growing season this can be supplemented with regular liquid feeding where necessary.
Some years ago we were troubled by self-seeding Myosotis (forget me not) so I always pull up any plants to prevent this happening again, the same goes for Aquilegia seedlings.
Penstemons can be lightly pruned back to encourage new bushy growth.
Evergreen hedges both coniferous and broad-leaved types may be trimmed this month ensuring you always leave some needles or leaves at the end of each pruned branch otherwise it will not grow out again.
Old clumps of Bamboo may be pruned or divide this month taking great care to protect yourself.
This is a good time to pollard Eucalyptus. Pune out any winter damage to trees and shrubs generally. Check and remove any non-typical growths on trees and shrubs such as reversion, fastigiate growth etc. Check and loosen any tree ties as needed.
Early flowering Primulas may be divided this month after flowering otherwise leave until early next month or postpone until September.
Any trees or shrubs that are late in developing may have been affected by the wet spring and might be attacked by Phytophora, a soil born disease that can lead to the death of plants, remove if necessary or take professional advice in the case of larger trees (check for tree preservations orders etc. before carrying out any work on trees)
Continue mowing the lawn on a regular basis, gradually reducing the height of the blade, and incorporate the trimming of edges into your weekly routine. Compost the clippings if possible. Keep lawn edges neatly trimmed, re-cut lawn edges if necessary.
If you have not done so already, feed the lawn now. Where powdered fertiliser is used, ensure that the grass is dry before application, but it is handy if rain is on the way because the powder will need watering-in within 48 hours. A nitrogenous fertiliser should be applied in mid- to late-May to encourage lush, bright green turf. The new range of lawn fertilizers from Viano and available in most garden centres are ideal as the small granules are designed to be organic, slow release and cannot scorch the grass if applied as recommended.
Good weather should be seen as an opportunity to deal with lawn weeds but remember that where chemical weed killers are used, the clippings should be added neither to the compost heap or used as a mulch which may present a problem during lock down.
The recent rains at the end of April make for ideal conditions for sowing new lawns, laying turf or carrying out over seeding of bare areas after creating a little tilth with a sharp tined rake to ensure the seed established in the older lawn. Lawn repair kits are available but very expensive and most contain very little actual grass seed. In all cases keep well-watered and protect from birds if necessary. I will also be carrying out a last light scarifying to remove the final remnants of the moss caused by the wet winter.
The Vegetable Garden
This month sees a continuation of hoeing and weeding of growing crops, watering in dry spells and feeding where necessary. Direct sown vegetables can be thinned out as soon as they are ready. Potatoes should be ready to earth-up.
Taller varieties of broad beans may also need to be earthed-up or supported and the tops should be pinched out after flowering to reduce the risk of black bean aphid infestations. Runner bean supports can be erected now so runner bean plants that have been hardened-off may be set out. Use cloches for protection during colder spells or in northerly regions.
Sow dwarf, climbing and runner bean plants in well prepared, open ground. A second sowing of broad beans can also be made. Early sown peas will need supporting now while dwarf and main crop varieties can be sown in succession. Similarly, sow maincrop carrots now and thin the earlier sowings when they are only finger thick. Parsnip seedlings should be thinned and further sowings of beetroot can be made for winter storage, thinning the earlier sowings to give room for development
Those of you who like sweet corn, and have the room, can sow or plant outdoors towards the end of the month. Growing sweet corn in rectangular blocks will help provide support and improve the chances of successful pollination.
Plant out hardened-off lettuce plants and continue to thin and sow seed in succession, remembering that slugs also like the soft foliage and must be controlled. Salad lovers should enjoy those radishes that are now ready for pulling. Sow more as space becomes available. It is also possible to plant out ridge cucumbers which have been raised in the greenhouse while tomatoes may be planted towards the end of the month provided, they can be given temporary protection if needed. Self-blanching celery should be planted out in blocks 25cm (10ins) apart in each direction to encourage upright growth.
From mid-May, in the south of the region, courgettes and marrow plants can be moved out into the open although they will still need protection from cold nights. The site should be well-dug and generously supplied with well-rotted manure. Further sowings of courgettes, marrows, pumpkins and squashes can be made under frames or cloches when conditions are sufficiently warm.
Broad beans may have the growing tips removed after the flowers show this will also encourage a bushier plant, making it a heavier cropper. A little earth may be drawn up around plants to aid their support.
Canes can be erected for early plantings of runner beans; I use old scaffold poles having got fed up with timber posts rotting over the years.
Carrots should be protected against carrot fly by covering with Environmesh.
Plant out summer cauliflowers, feeding and watering them, treating for root flies and controlling slugs where there is a problem. Precautions should also be taken against club roots. This also applies to summer and autumn cabbage, red cabbage and Brussels sprout seedlings planted now. Savoy cabbages can be sown for transplanting later. Seedlings of sprouting broccoli can be thinned, keeping a watch for flea beetle. Spring cabbage should be gathered as it matures.
Asparagus may also be ready for gathering. Spears should be cut just above the crowns when they are 6ins long. Never let the spears grow too tall before cutting. More crowns can be planted in trenches 3ft apart, remembering not to cut the spears on these as they should be allowed to develop into bushy fern-like stems in their first year.
Feed and mulch artichokes this month, and thin out suckers to leave the strongest. Apply fertiliser to onions and thin out bulbing onions which were directly sown. Salad onion crops will also need thinning, and further sowings can be made for a continual supply. Leek transplants raised under glass can be planted out and more seed sown directly into the ground.
Earlier sowings of Beetroot and spinach can be thinned out at this time, ideally when the ground is moist.
Baby vegetables are becoming very popular especially where space is limited. Many can be sown at this time and can be grown in containers and growbags on the patio as well as in the vegetable garden. However, should soil conditions be cold and wet, delay sowing.
In the herb garden, Parsely and other hardy annual herbs may be sown as required. Thin seedlings from earlier sowings. Perennial herbs can also be sown now, and container grown ones planted. Lift and divide any established overcrowded clumps.
The Fruit Garden
Newly planted fruit must be kept well-watered and should not be allowed to fruit until well established.
Harvest rhubarb but never pick more than one third of the total number of stems.
The preventative spray programme should continue on top fruit at post-blossom and fruitlet stages. Weeds also need to be controlled, regularly clearing them from around the base of the trees and any suckers should be pulled from apple rootstocks as soon they are noticed. Early maturing apples can be thinned to leave 6ins between the fruits. Weak growing pears will benefit from feeding and mulching now.
Keep an eye on fan-trained trees and rub out any unwanted shoots such as those facing the wall. Peaches and nectarines should be carefully disbudded and red spider mite controlled by regularly spraying with derris or pyrethrum insecticide. Cherries can be pruned now if deemed necessary.
You may continue to plant container grown fruit trees, bushes and canes this month, giving them a good after-planting drink and mulching. Recently planted fruit trees should be examined and flowers removed, leaving the basal cluster of leaves.
The old wood on gooseberries can be thinned out, clearing away weak and crossing branches at the centre of the plant. The fruits can be thinned a little if necessary but take care not to over thin at this stage. Gooseberries will also appreciate a feed and mulch, as well as a spray against green gooseberry sawfly caterpillars, capsid bug, and aphids. Currently I do not believe there are any fungicide available for mildew on Gooseberries or any other edible crops, always read labels before using fungicides or pesticides and adhere to the rules.
Raspberry canes should be thinned to 3ins apart, removing suckers which are growing outside the row; then feed and mulch. On loganberries the basal suckers require thinning and tying-in as appropriate before the plants are given a feed and mulched. Long growths on blackberries will be ready for tying and, as well as feeding and mulching, may need a spray to control cane spot and spur blight. Give a light feed to red and blackcurrants and spray to control leaf spot, aphids, sawfly and caterpillars.
Just as strawberries are irresistible to children, so birds find them a tasty meal and for this reason plants should be netted now. Strawberries also need protection from the soil. Use straw or black polythene underneath the fruit. Pay attention to shading and ventilation of any strawberry plants under cloches and remember to remove the flower stalks as they appear on any that were planted this spring.
Grape vines should be fed and mulched. Reduce shoots on spur pruned vines to one spur, leaving leading shoots unpruned. Remember fungicides are not available for mildew on fruit or vegetables so pay special attention to pruning and watering to prevent mildew occurring.
Hang pheromone traps in apple trees to reduce codling moth. This alone may not be sufficient to eradicate the pest and other means may be needed such as chemical sprays.
Hang pheromone traps in plum trees from May to August to monitor plum-fruit-moth activity rather than expecting control of the pest.
Although the sides of my fruit cage remain in place all the year, I always pull the roof back in early may too protect developing fruitlets especially cherries which otherwise are3 a favourite with pigeons.
The Indoor Garden, Conservatory or Greenhouse
Monitor the temperature in greenhouses and conservatories, increasing ventilation if necessary or simply damping down beds and paths to lower temperatures. Water in the early morning rather than during the day when young growths especially may scorch.
It is likely that shading will be required from this month onwards. Blinds or a shading wash can be used. In addition, attention should be paid to ventilation, especially on warm, sunny days. If the weather turns very warm, extra humidity will be required. This can be achieved simply by damping down the floor and staging when necessary throughout the day.
The onset of warm weather increases the spread of pests and diseases. Any such problems should be controlled as soon as noticed but it will also help if plants are spaced far enough apart to provide a good air flow between them. Spacing also helps ensure sufficient light reaches each plant to promote healthy growth. Moisture loving plants can be plunged into containers of damp peat and stood on damp pebbles. Hang sticky cards in greenhouses or conservatories to both monitor and trap pests.
Measures should be taken to guarantee composts do not dry out and shrink. Hanging baskets made up earlier this month will require special attention to prevent them from drying out whilst under glass, and you should aim to finish planting them up as soon as possible to encourage growth before putting them outside. Pendulous begonias, started in boxes, will now be ready for use in baskets.
Sow runner and French beans in small pots to plant out later this month, do not over water as this may lead to seed rotting.
Marrow, courgette and sweet corn should be sown in individual pots in the greenhouse and also outdoors in situ at the end of the month, into early June.
The majority of bedding plants can be hardened-off this month. Trailing fuchsias should have the growing points pinched out to encourage a bushy habit and vigorous growing plants may need potting-on into larger containers.
Always prick out any seedlings at the earliest possible opportunity as this makes for better plants.
Regular pinching out of the growing tips of many subjects makes for bushier more floriferous plants and is a good practice on subjects such as Fuchsias and Geraniums.
Begonias and gloxinias raised from seed will require potting-on, and cuttings taken earlier in the spring, including dahlias and late flowering chrysanthemums, should be examined and potted into individual pots when well-rooted. More propagation may be done now.
Seed of Cinerarias and Caleolarias may be sown this month. It is also a suitable time to take cuttings of azaleas, poinsettias, begonias and other houseplants as well as pelargoniums and perpetual carnations for autumn-flowering plants. And there is still time to take cuttings of chrysanthemums. Hydrangea cuttings may be taken if you are looking for new plants to flower next year. Chlorophytums should be pegged down to form new plants.
Continue to feed houseplants, keeping the leaves clean and misting the plants with tepid water in warm weather. Early tomatoes should also be feed regularly with a proprietary plant food. Tomatoes for the cold house should be ready for planting into pots, growing bags, rings or soil. Support and train the plants as necessary.
Cucumbers, melons and sweet corn should be planted as soon as possible.
Auriculas which flowered in the greenhouse may now be moved to a cool spot.
Looking good this month
Aeculis (horse chestnut),
Sorbus (whitebeam, mountain ash)
Exochorda, Genista hispanica,
Kerria japonica, tree peony,
Ribes sanguineum and varieties,
Clematis montana and cultivars,
Geum coccineum hybrids,
Papaver orientale and varieties,
Phlox divaricata varieties,
lily of the valley,
Narcissus Jonquilla varieties, N. poeticus recurvus,
dwarf bearded Iris
Conservatory / Greenhouse
Primula kewensis, P. malacoides
Around the Home
Vegetables in season
Fruit in season
The information given in this Fact Sheet is provided in good faith. It is however of necessity general information and advice on the topic. Howard Drury will not be under any liability in respect of the provision of such advice and information and you are strongly advised to seek independent advice on any particular gardening problems or queries you may have, preferably from experts who can (when appropriate) inspect the problem before providing advice.
(C) 2020 This material has been produced by Howard Drury and must not be reproduced in part or full electronically or otherwise without the prior written consent of Howard Drury, Kings Heath Birmingham, B13 0SJ.