Gardening News, Advice, Tips and Jobs For April 2021
Advice, Tips and Jobs for April 2021
By Howard Drury
I have delayed writing my advice, tips and jobs for April until the last minute due to the Corona Virus problems and the forecast sudden change to much colder conditions for the whole country. We have been hit with a three way storm, we have the over zealous effects of Brexit and the plant health regulations which together make it almost impossible to import plants from the European Union and elsewhere due to the hold ups at inspection points. Typically it is costing an extra £400 per pallet of plants yet the Dutch cut flowers seem to sail through.
Secondly the effects of world trade means less containers are being shipped around yet the cost of these massive ships remain the same regardless of how many containers they are carrying. They divide the costs by numbers of containers and the rise in shipping generally has risen from around £2100 per container to over £10,000, increasing costs of goods massively in garden centres and shops. Then because of Covid 19 we have a shortage of raw materials with huge shortages world wide. Recently I could not buy pot saucers as both Stewart and Sankey seem to be manufactured in China. Polythene is in short supply due to less oil being used and suppliers have decided to use what they can get hold of to make PPE as there is considerably more money in that then compost bags!.
Then we have the anti peat people who have forced the closure of the Irish peat fired power stations putting almost 5,000 in the industry out of work and the surface peat gardeners used is not being cleared for the deep peats to be burned for electricity. What has happened? They have installed wind turbines many on the the very peat bogs we were getting peat from causing massive environmental issue with roads, concrete foundations and vibrations, once constructed these are causing havoc to wild life especially birds.
The search for alternative goes on compounded by the Royal Horticultural Society banning peat in its gardens and shops by 2025, meaning growers have to source liners grown in peat free mediums and this is proving very difficult. As is the fact we have an extra 3 million new gardeners following the lock downs. Daly manty do not understand the term potting compost or a one compost manufacturer described it as a growing medium. Is is not compost in the same way gardeners us garden compost to improve their garden soil. Bark based is my favourite alternative but Melcourt pointed out we simply cannot find more trees to cut down it is a long term cycle we cannot squeeze any more bark out of.
There is an alternative, it is to make growing media or potting compost go further. This is easy to achieve by simply planting in the ground rather than growing in pots baskets an other containers. We can revitalise and sterilise existing composts. We can stop the rather silly practice of using vast amounts of potting compost to grow a few potatoes in a polythene bag or very large pot. Subtle changes but they can really help.
Please then, if you go into a garden centre and some plants and products are missing dont complain, it could be like in the case of Alpines none were propagated during last years lock down and one huge nursery closed, result shortages all over the country.
This month will see Suttons Seeds delver into garden centres and direct to customers their range of grafted fruit and vegetables which have proved to be high yielding and less trouble grow than conventional seed raised plants. Tomatoes grafted onto special root-stocks will grow in the same soil year after year without any of the problems growers used to experience and the extra cost. However you will only be able to get these through local deliveries with garden centres likely to be closed for some time. i think their website has stopped taking orders at the moment.
Remember my notes are based on gardeners living in the Midlands; those of you outside these areas will have to adjust according to the local climate and the prevailing soil conditions and the latest legal position accordingto the UK government. Please do not break any laws in trying to garden.
The best advice must be to work with the weather and commonsense. We had been lulled into a false situation, thinking that all frosts are past, be warned we have had frosts as late as mid June in the past often following a mild early spring! just look at the temperatures at the end of March and within a few days temperatures have halved with damaging frosts forcast for the first 10 days of April. Wet ground will need careful cultivation to get air into the soil, soil structure needs careful management to open it up and keep it open, nutrition levels will need checking with a simple tester kit and most lighter free draining soils will benefit from a topping up of nutrients with a good slow release fertilizer such as Vitax Q4, which is slightly better than the old favourite Fish, Blood and Bone meal, having more balanced trace elements.
April is likely to be the month of the weed. The mild winter and the recent warm sunny days have encouraged a proliferation of seeds to germinate from cultivated plants to obnoxious weeds. Weeds in bare areas are easily treated with non selective weed killers but where weeds are growing amongst plants April is a good month ease out the weeds before they overtake better garden plants and this year lawn weeds are growing well enough to be treat with a selective hormone lawn weed killer later this month. Please do make sure you only use selective hormone lawn weed killers on turf, non selective total weed killers such as Roundup will kill everything where it touches green foliage including your lawn!
Japanese knotweed usually appears this month, it is regarded as a serious weed that can cause serious damage to structures and devalue property. If you see any possible shoots it is best to seek professional advice rather than trying to dig it out yourself or treat it with amateur products. A quick search of the web will usually bring up a list of local specialists capable of advising you and treating the weed. Remember it is a serious offence to let it spread from your property to adjoining properties or public spaces.
Work with your local weather and local micro climate to time jobs, remembering heavy clay soils are slow to warm up in spring compared with lighter sandy soils. Across the midlands there will be significant differences, some areas are already cutting grass while in neighbouring areas there is no sign of any growth. Also any flooded or very wet soils are best left until the become drier and workable.
Make sure greenhouses conservatories and cold frames are airtight and not losing heat.
Start many subjects into growth indoors as soil temperatures are still too low for sowing and planting many vegetables.
Have some form of insulation or heating for the greenhouse or conservatory, otherwise delay growing tender plants until temperatures rise.
As soon as conditions permit carry out delayed tasks such as spring moss control in lawns, it is too cold to apply lawn herbicides, as weeds are not yet growing sufficiently. if due to Coronavirus restrictions you cannot get moss killer a thorough scarifying is good practice as early in the month as possible.
Any bulbs, corms or tubers being kept indoors for planting need keeping as cool as possible to prevent dehydration but must be maintained frost free.
Start onion and shallot sets into growth in small pots indoors if the ground temperatures remain cold and plant out later in the month.
Water any indoor and greenhouse plants carefully, being so cold and with low light levels few plants actually need much water at present, especially if recently re-potted. Keep water off the foliage and water in the morning rather than later in the day.
Use a three pronged cultivator to stir soil do not dig deeply bringing cold soil to the surface especially where planning to sow seeds or plant out young plants.
Be wary of less reputable on line suppliers and supermarkets along with corner grocery shops trying to sell tender plants such as summer bedding too early this season when it is unsafe to plant outside and you do not have facilities to keep them frost free and in good condition.
The Flower Garden
Aerate the soil wherever possible using a fork or three pronged cultivator without damaging plant roots. Border may be top-dress with an organic mulch and lighter soils may need feeding to compensate for nutrient loss due to the heavy rains in addition to normal feeding to promote quality growth as normal.
When soil conditions are possible sow hardy annuals in their flowering positions. Ideally possible choose a showery day for this task as it speeds up germination.
Plant Gladioli corms over several weeks for a longer continual display over several weeks. Lift and divide snowdrops into smaller groups. Dead head spring-flowering bulbs as they finish flowering. Plant out bulbs that flowered indoors during the winter.
Plant Chincherinchees in a sunny place 10-12cms (4" 5") deep, 5-7cms (2' 3') apart. Ranunculus can be planted 5cm (2") deep, 7-10cm (3” 4”) apart and watered copiously in dry spells. Plant Galtonias 12cm (5") deep in places where they will not be disturbed. Plant Anemone de Caen/St.Brigid varieties from April to June for flowering from June to September.
Plant out herbaceous from pots although there will be less top growth this year than the norm. Take cuttings of hardy border perennials, i.e. Delphiniums, Lupins, Heleniums, and Phlox etc. Lift and divide any herbaceous plants before too much top growth appears as plants re-establish better this way, watering in well afterwards.
Sow sweet peas seeds. Plant out glasshouse raised sweet pea seedlings. Guide sweet peas up supports as they begin to grow. Remove side shoots of cordon-grown plants.
Thin out shoots on herbaceous plants such as delphiniums and Lupins to encourage fewer and larger flowers, apply fertilizer then mulch the area. Support herbaceous plants where necessary with unobtrusive methods using natural materials or proprietary plant supports.
Established clumps of lilies maybe top-dressed with peat or leafmould. Lily seeds can be space sown in pots and stood uncovered outside but may not germinate until next spring. Liliums may be planted according to soil requirements/shade conditions. There are several good compact forms of lilies that are ideal for container growing and should be potted as soon as possible.
Crinum powellii can be planted in a sunny spot to flower in September, cover with insulating materials such as bracken to protect against winter cold, only choose hot sunny well-drained sites to ensure regular flowering
Pot grown Clematis can be planted slightly deeper than they were growing in the pot to protect against clematis wilt and encourage a well-branched plant. Protect with a collar against slugs and snail or use slug pellets. Tie in young shoots on established clematis regularly.
Prepare sites for Chrysanthemums and Dahlias grown from cuttings with plenty of manure. Dormant Dahlia tubers can be planted at the end of the month in the Midlands, weather permitting. Plant out hardened off early flowering Chrysanthemums towards the end of the month.
Plant up any gaps on the rock garden over the next few weeks allowing plants space to grow according to cultivar or species. Top up gravel or chippings on rock gardens. Keep the rock garden clear of all weeds using small weed fork, or even an old dinner fork. Take precautions against slug damage on rockeries.
Give spring flowering plants a boost of fast acting fertilizer such as Growmore or Vitax after tidying up and lightly cultivating the soil. Dead head any spring flowering subjects such as Violas and Pansies where flowers have faded to get maximum flowering.
Water lilies and other aquatic plants can be planted during the next few weeks in sheltered areas. Purchase plants and fish for garden ponds. Construct new pools. Existing pools will require some maintenance, tidy up plants, dividing these were necessary. During periods of any warmer weather and signs of activity from fish, a little feeding can commence. (all these tasks may be impossible due to Coronavirus)
Keep hedge bottoms clear of weeds and ivy, lightly trim evergreen hedges this month and there is still time to plant evergreen subjects as hedges this month. Feed starved hedges such as Laurel and Berberis especially on lighter soils. Mulch if practical especially on sandy soils
Start to harden off the hardier bedding plants such as Antirrhinums. Pinch out the growing points of Antirrhinums, Salvias and Petunias to encourage bushier plants that will flower more prolifically.
Gap up and thin out hardy annuals when soil is moist. Carefully weed hardy annuals as soon as practical after the seedlings appear.
Finish pruning roses if not already done so. Remove all dead and diseased wood, pruning back to outward facing bud. Apply high potash Rose fertilizer to rose beds. Spray roses against black spot/mildew and also against aphids. Plant pot grown miniature roses, prune to shape only and water in.
As Forsythia finishes flowering some older branches maybe selectively pruned back where there is a lot of old and over-crowded growth leaving one or two buds on new wood, which will flower in two years’ time.
After the heavy rains of the last year many flowering shrubs will benefit from a generous dressing of a high potash fertilizer or a rose fertilizer at the rate of 30-60 grams (1‑2ozs.) per square yard, especially those on light sandy soils. Shrubs that produce flowers on this year’s growth can be pruned now such as Spirea 'Anthony Waterer'.
Plant container-grown deciduous trees and shrubs. Continue planting evergreens and water in well during dry spells. Newly planted evergreens, especially conifers can be scorched by strong winds and should be protected with a screen of polythene netting to reduce wind speed and transpiration.
Layer Rhododendrons by pinning a low growing branch to the soil. If absolutely necessary transplant recently planted magnolias complete with root ball of soil just as growth commences. Established Magnolias will not normally survive being transplanted.
Prune back hard any overgrown Box, Holly, Laurel and Yew as buds begin to burst. Check over variegated shrubs and trees removing any reverted growth. Clip Ivy on walls after checking for birds nests; prune Virginia creeper and Vitis coignetiae.
Watch for greenfly on Polyanthus and Primroses and spray accordingly. Ensure that these plants do not dry out during sunny spells. Apply Provado to protect against the larvae of vine weevil.
Spray weeds in paths with weedkiller and consider re-grouting after the wet winter season.
Watch for slug damage and take necessary steps to control.
Remove old discoloured leaves from Bergenias, prune Penstemons, replant or mulch old leggy Heucheras. Trim back Phygelius to maintain compact bushy shape. Tidy up old Sedums (Ice plants) removing old dead stems previously protecting young shoots.
Remove any old discoloured foliage from Hellebores, especially if they show signs of leaf spot. Spray regularly with a systemic fungicide and grow plants well to beat the disease. Mulch with mushroom compost and give a slow release general feed. Watch out for aphids when the weather warms up, there is a relatively new Hellebore specific aphid which can also transmit viruses between Hellebores, spray at first signs.
Many herbaceous plants can be divided this month such as grasses provided they are kept well watered during dry spells. Trim back the dead foliage on deciduous grasses without cutting into new growths. Some gardeners like to trim the evergreen grasses may also be pruned to clean them up.
Overcrowded Nerines may be divided this month, lift carefully with a fork where ground in the ground, tease apart carefully only replanting or potting quality damage free bulbs to minimise the risk of rotting. Where potting use the smallest pot possible to encourage flowering in as short as time as possible.
This month looks like providing ideal conditions for turf laying or minor turf repairs by reversing damaged edges and raising sunken or low lying areas, Do not apply deep topdressings more than 12mm (½") deep as it may kill the turf.
Edges to lawns may be re-cut to improve appearance, leave an outward slope to minimise damage when walking near grass edges.
Lawns would normally now need regular mowing and edging, keeping mower blade at least 25-38mm (1‑1½") high.
Sow new lawns and re‑seed areas that are rough, patchy or damaged. Protect all newly sown areas from birds. Check newly turfed areas and top dress where necessary. Look out for Johnson's Any Time grass seed mixture, which germinates at much lower temperatures than other mixes, possibly very important this year.
Spike established lawns with special fork to aerate and improve drainage. Give lawns a light raking to remove dead grass and thatch.
Feed and weed lawn towards the end of the month. Apply a lawn feed such as Scott’s Lawn Builder in advance to encourage the growth of both grass and weeds as the lawn hormone weed killers are much more effective on active rather than dormant weeds.
Moss is a major problem this spring and the late season means there is every opportunity to carry out moss removal using physical and chemical methods that should have been carried out in March. Take care not to damage any weak growth when raking out the moss.
The Vegetable Garden
Plant globe artichokes in well manured soil (these may also be used in the flower border as a decorative plant). Plant asparagus crowns in single rows or beds. Asparagus seed can be sown outdoors on a well-drained open site.
Brussels sprouts sown earlier in cold frame can be pricked out into rows 15cms (6") apart. Alternatively grow plants from seed sown in cool indoor conditions and pot on to large pots using a loam based or peat free compost to minimise the risk of introducing club root to the vegetable garden. Spring cabbage should have a light dressing of nitro chalk.
Prepare celery trench incorporating well-rotted manure. Prepare a site for annual herbs to be sown, conditions permitting at the end of the month, i.e. basil, coriander etc. Prepare trenches for runner beans to be sown or planted incorporating well-rotted manure or garden compost.
Sow broad beans, beetroot, broccoli, cabbage, carrots, cauliflower, kale, leeks, parsnips, lettuce, onions, spinach, radish, spinach beet, sprouts and turnips in the open ground as conditions permit.
Complete planting of early potatoes; in mild areas commence planting main crop varieties. Earth up early potatoes and protect any new shoots against frosts.
Sow French beans in open ground and sow main crop carrots for autumn and winter use. Provide early sown peas with supports.
Watch for flea beetle on cabbage family seedlings a spray or dust of the following are effective, contact insecticides containing natural pyrethrins (e.g. Bug Clear Gun for Fruit & Veg, Ecofective Bug Killer). Several application of these short persistence products may be necessary to give good control. A wide range of brassicas can be sprayed with the more persistent synthetic contact pyrethroid insecticides lambda-cyhalothrin (e.g. Westland Resolva Pest Killer) and deltamethrin (e.g. Provanto Ultimate Fruit & Vegetable Bug Killer)
Sow winter greens such as winter cabbage, broccoli and Savoy cabbage.
Make a new mint bed. Sow parsley and salad crops. Continue sowing outdoors for continuous cropping. Lettuce should be sown (under glass or outside) every 14 21 days for a continuous supply.
Harden off seedlings of brassicas; leeks and onions raised under glass and later in the month plant out into growing positions. Thin out outdoor sowings of vegetable seedlings to correct spacings to encourage quality plants and crops.
Protect tender or frosted plants from morning sun by covering with newspaper until they have thawed. Water in any new plants and seedlings as and when necessary. Keep a watch out for pests and diseases and treating immediately. As soon as earlier sowings are visible, run a hoe along the rows to control weeds.
For an early crop, plant leek seedlings in prepared trench or drop in holes.
Cut off any flower heads from rhubarb as soon as they can be recognised and before they develop and weaken the plant.
Any vacant cloches or modern plant protection covers can be positioned over soil for later sowings. As the weather hopefully improves, take care to ventilate crops already growing under glass, cloches or frames, water and thin out when necessary.
Control slugs and snails when necessary.
The Fruit Garden
Be prepared to protect smaller fruit trees against frost damage to blossoms using materials such as fleece where possible.
Prune plum trees only where really necessary and spray against aphid attack at pink and white bud stage with suitable insecticide. Apple trees should also be sprayed against pests, mildew and scab using a insecticide and fungicide. DO NOT spray trees whilst in full flower. Any mildew infected flower trusses on apples trees are best cut out and burned.
Spray pear trees with insecticide / fungicide just before they come into flower.
The following fungicides are recommended for top fruit, difenoconazole (Westland Plant Rescue Fungus Control) and myclobutanil (Bayer Garden Systhane Fungus Fighter) can give good control of most fruit tree diseases when used according to the schedule recommended by the manufacturers. Please check labels for specific uses and limitations.
Prune any fruit trees that show damaged, diseased and dead branches back to new healthy wood from all fruit trees and check ties to ensure they are not too tight.
Pollinate wall fruit such as peaches and nectarines by hand by shaking branches or using a suitable brush etc. during warmer parts of the day.
Disbudding peaches and nectarines can now begin to rub out back-facing/front buds. Watch for aphids and treat immediately.
Watch all newly planted trees and bushes to ensure they do not suffer during any dry periods. Water thoroughly and mulch.
Plant container grown fruit, including figs and grape vines. Complete the planting of currants, gooseberries and raspberries.
Give gooseberries 60 grams (2oz.) of sulphate of potash per bush if not applied earlier in the year. Currently there are no fungicides available to control against American gooseberry mildew just before the flowers open.
If strawberries were not planted in late summer last year, plant now. Deflower newly planted strawberries. Cloche or fleece strawberries for early crop and to protect flowers from frost water regularly to swell fruit. Keep strawberries and raspberries free from weeds by regular hoeing. Spot treat any established weeds such as docks and thistles etc. with a weed killer rather than disturbing roots of established fruit.
Spray raspberries against raspberry beetle and mildew with an insecticide. Continue removing and destroying any blackcurrant branches infested with big bud mite and spray.
Glasshouses and Conservatories
After the low light levels of winter some shading of greenhouse and conservatories may be required if bright sunlight occurs that may damage the soft foliage of plants. Take care with begonias, cucumbers and impatiens. Move such subjects to a shadier place in the greenhouse or conservatory.
Gradually increase the amount of water given to plants as they show more signs of growth, feeding can be gradually increased to that recommended by manufacturers on established plants, newly potted plants will not normally need feeding for the first six weeks or so.
Finish sowing half-hardy annuals as soon as possible. Prick out and pot on earlier sowings as they develop.
Sow seed of outdoor tomato varieties. Plant out tomatoes in the heated greenhouse in growbags, rings or in the prepared border, water well but do not begin to feed yet. Early planted tomatoes will require side shooting.
Sow Peppers and Aubergines in heated greenhouse. Sow French Beans, Marrows, Courgettes and Sweet corn. Sow seeds of melons and cucumbers two per pot in temperature of 18ºC (65F). Sow celery seed.
Hand-pollinate vine flowers by drawing a half-closed hand down trusses to spread the pollen. Tie in vine rods, as growth should be sufficiently advanced along the rods. Young growths of vines should be pinched out to two leaves beyond fruit trusses. If two bunches form on one lateral, remove one.
Tubers of Gloxinias and Begonias started off in trays will now be ready to pot on. On bright days, these will require shading. Pot up tuberous double Begonias, with the flat side of the tuber uppermost in the compost and then grow on at 13- 18ºC (55 65F).
Take cuttings of indoor hydrangeas, begonias and other flowering and foliage plants, as material becomes available. Pot up any rooted cuttings.
Move bedding plants and vegetables to cold frames to harden off towards the end of the month. Move pans of Alpines back into cold frame as they finish flowering. Prick out alpine seedlings as they become ready.
Start feeding houseplants with nutrient sticks, drips or regular liquid feed.
Now days we recommend feeding and watering cyclamen corms until they naturally want to die down, with first year indoor cyclamen this is very important as it helps establish a larger corm.
Sow summer flowering pot plants such as Browallias, Coleus and Celosia. Start Achimenes into growth in warm greenhouse in batches to give successional flowering.
Pot on young Chrysanthemums and Fuchsias before they become pot bound. Stop Chrysanthemum and Fuchsia plants rooted in February, by pinching out growing points.
As soon as weather permits, transfer rooted Chrysanthemum cuttings to cold frame. Train young Fuchsias to form standards.
Pinch out tops of tall and leggy geraniums to encourage bushy growth.
Propagate Streptocarpus by division of leaf cuttings. Make sowings of Primula malacoides and prick out seedlings of Primula obconica.
Divide Agapanthus, Arum Lilies, Chlorophytum, Ferns and Peperomia. Pot on pot grown Camellias into slightly larger pots as soon as they have finished flowering using loam based ericaceous compost or John Innes No 2 plus composted bark to counteract the lime and lower the Ph of the compost.
Make up hanging baskets using well-stopped and well-branched subjects, this way fewer plants will be needed than later in the season. Carry on with pricking out half-hardy annuals as required. Use plastic modular cells to avoid root disturbance when planting out in the garden.
Increase ventilation on sunny days and increase humidity. Very tender seedlings will require shading from strong sunlight. Spray seedlings with fungicide when damping off occurs.
Control aphids, white fly, leaf miner and other pests Organic sprays, such as natural pyrethrum (e.g. Bug Clear Gun for Fruit & Veg, Ecofective Bug Killer), fatty acids (e.g. Solabiol Bug Free, Doff Greenfly & Blackfly Killer) or plant oils (e.g. Vitax Organic Pest & Disease Control, Bug Clear for Fruit and Veg) can give good control of whitefly nymphs. These pesticides have a very short persistence and so may require reapplication to keep whitefly in check. Plant oil and fatty acid products are less likely to affect larger insects such as ladybird adults and can be used with care, prior to introduction of biological control. Organic products can also be used on edible plants provided label instructions are followed
More persistent insecticides include the synthetic pyrethroids lambda-cyhalothrin (e.g. Westland Resolva Pest Killer), deltamethrin (e.g. Provanto Ultimate Fruit & Vegetable Bug Killer) and cypermethrin (e.g. Py Bug Killer). There are resistant strains of whitefly to these products. Products containing deltamethrin, cypermethrin and lambda-cyhalothrin can be used on edible plants listed on the label provided instructions on maximum dose and harvest interval are followed.
Edible plants can be sprayed with plant oils, plant extracts or fatty acids. The latter pesticides may require more frequent applications.
Looking Good This Month
Depending on this very unusual season and your locality, the following plants should be looking good at some stage during the month.
Convallaria (lily of the valley)
Clematis alpine and cultivars
Spirea arguta S. thumbergii
Viburnum inc. V. Eskimo’ AGM
Vinca major cultivars, V. minor and cultivars
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.