In your ornamental garden in May 2013

Contents

• General tasks
  • First half of May
  • Second half of May
  • Starting a new garden?
• Greenhouse
• Lawn and hedge care
• Pond management
• What to plant in May
• Make new plants
• Easy perennials
• Pest and disease watch
• Houseplant care

General tasks

May gardening jobs often divide fairly neatly into two sections – those for the first half of the month, and those for the second half. But it’s all down to the weather and your locationin in the UK – specifically soil and air temperatures. And of course the long winter has left the soil so much cooler than usual at this time of year. If your weeds are growing well, with dandelions flowering, then your soil temperature is fine for seed sowing. If dandelions are still not doing much, just be patient a little longer.

First half of the month

• Prune spring-flowering shrubs as they finish flowering. Forsythia spp, Spirea arguta (Bridal Wreath), Jasminum nudiflorum (winter flowering jasmine), Deutzia spp, Clematisis montana and C.alpina, all flower on growth that will be made in the coming season. Cut them back now, bearing in mind that they will put on growth during the rest of the season which will be next year’s flowering stems. So if you want a smaller plant next year, you need to cut back hard this year.
• Cut back evergreen ceanothus. Take two thirds off each new shoot once flowering is over.
• Cut out weather- damaged growth from plants such as phormium and hebes. The cold winds this spring may well have killed off some leaves and stems. Cut back to the base, or back to live tissue, to encourage new growth to form. Give such plants a boost with a handful or two of garden compost lightly forked around them.
• As the stems of climbing plants lengthen, tie or tuck them in to their supports. Don’t allow matted tangles to develop. They prevent flowers from being clearly visible.
• Tie in climbing rose stems horizontally, to encourage flowering points to sprout where you can see and enjoy them.
• Provide sturdy wire supports for wisteria, as it is a large and heavy plant. Don’t let it climb up the telephone wire!
• Clip back ivy if necessary and only if birds are not nesting in its dense foliage.
• Pull off suckers from shrubs such as roses, lilacs, and any grafted plants where the suckers are emerging from below the graft union. Use pliers to get a good grip, and dig down towards the main stem to get as close to the joint as possible. Don’t cut suckers off as that leaves a growth bud from which a new sucker will sprout.
• Once flowering is over, give aubretia (and winter heathers if you’ve not already done them) a good haircut. Use shears to trim back to a neat mound.
• Once pulmonaria and epimedium have finished flowering, trim stems and foliage hard back.
• Stake perennials before they get too large and begin to flop.
• Divide large clumps of spring-flowering perennials, such as Doronicum, poppies and Primula spp.
• Deadhead all bulbs as flowers finish, and feed with a dressing of garden compost, or manure. Fork in lightly. Leave foliage to die back naturally for at least 6 weeks after flowers have died.
• Use short bamboo canes to mark out areas around bulbs to avoid accidentally digging into them later in the year. The canes will soon vanish among summer growth of annuals and shrubs. This also helps to identify spots where new bulbs are needed

• If you need plant supports, such as trellis for climbers, why not make your own? It’s easy, and you can chose a design of your own, as well as using untreated wood. Stain to your own colour preference.
• Install a water butt, if not already done. Check out Garden Organic’s Top Ten Tips for water saving this year. It’s always wise to be water-wise! Droughts can occur just as easily as deluges.
• Mulch bare soil after rain to retain soil moisture. Last year’s leaves will make a good mulch. Or you can use several thicknesses of newspaper, covered with bark chips, or even grass clippings. The more soil you can cover, the more moisture you’ll retain. Make sure that the soil has warmed up enough – wait until you see weeds actively growing before you mulch.
• New plants should have extra care. In dry spells keep them well-watered. Make a shallow depression around each plant to hold water where it is needed, and mulch as above.
• Early May is your last chance to sow half-hardy annuals (in warmth), to be sure of getting flowers this season. Don’t delay!
• Take regular walks around the garden and look out for potential signs of pest and disease. And take a hoe with you. Frequent hoeing is the best way to deal with weeds.
• Starting a new garden? Weeds everywhere? Feeling overwhelmed by it all? Just cover the weeds with a light excluding mulch. Cardboard, several layers of newspaper covered with grass clippings, or a weed suppressing membrane, will stop weeds growing. Yes, even dandelions! Ideally leave the mulch until next spring, but at least until late autumn. To improve appearance, cover over with bark chips (you can use these later on paths). Make small slits through the barrier, and plant small clumps of annuals, or specimen plants. Spreading plants like nasturtiums, or ornamental gourds (or even courgettes) work really well as cover plants and give interest to a garden while the weeds are being controlled.
Garden Organic members have online access to our factsheet: Weed prevention and Control
Find out more about Garden Organic membership.
A wide range of weed-suppressing materials is available from The Organic Gardening Catalogue

Second half of the month

• Cut back poppies once flowering has finished, and deadhead tulips.
• Start to harden off half-hardy annuals mid-month. This is a very boring job, but is essential if these rather tender plants are to flourish when they are planted out. This hardening off activity also applies to hanging baskets.
• Days 1 – 5. Take plants out of the greenhouse during daytime only, (and only if the weather is reasonable), and return late afternoon. In bad weather, leave plants in the greenhouse, but open the door halfway. Or, if growing on windowsills indoors, take plants outside, but cover with fleece.
• Days 6 – 10. Take plants out during the day, return early evening, and leave the greenhouse door ajar overnight.
• Days 10 – 15. Take plants out and leave out overnight, but cover with fleece.
• Days 16 onwards. Leave plants outside, but be ready to cover with fleece should the weather turn cold.
• At the end of the month, plants should be ready to plant out. But watch out for late frosts. If in doubt, cover plants with fleece, and wait a little longer.
Ground frost and air frost – the difference. Air frost is when the air temperature at around waist height is cold BUT the ground remains frost-free. This is more usual in autumn, when the ground still retains the summer’s warmth. Ground frost is when the  temperature at ground level has also dropped. May often has hot sunny days, but cold nights as the soil has still not warmed up to any great depth. And half-hardy plants will suffer if exposed to frosty air overnight. So listen to the weather forecast, and manage your plants accordingly.
• Clear containers of fading spring flowers. Remove the top 10cm/4” of potting compost, and replace with fresh material mixed with a couple of handfuls of garden compost or some similar fertility material. Plant out with hardy annuals, or, once they’re hardened off, half-hardy annuals.
  
  A speedy, and inexpensive, way to plant containers is to mix a selection of hardy annual seeds (especially nectar-rich ones) with some potting compost, then scatter over the top of the container. Water, then cover with another light scattering of compost. This is a great way to get summer interest in a container where tulips have flowered, and are starting to die back.
• When planting up porous containers, such as pottery or wooden ones, line the interior sides (only) with a plastic inner. This will prevent evaporation and keep moisture around plants’ roots. Kitchen bin liners make good linings. Cut the bottom off the bag, pop into the container and spread out round the sides so that the container base is clear of plastic. Put some drainage material in to cover the base, then some compost to weigh things down and hold in position. You should now be able to trim the top of the bag so that it doesn’t show over the pot rim. Continue filling with potting compost as usual and plant up.
• Going on holiday? Even a couple of days away at this time of year can be a problem for seedlings in small pots and trays. Not all neighbours are helpful! To prevent your plants from drying out, scrape out an area of bare soil, water it well, then sink any pots/trays into the hollow you’ve excavated. Mound soil halfway up the sides of pots/trays. Water the pots well. This should be enough to maintain sufficient moisture for a few days absence. This works for larger pots as well, you just need deeper holes to sink the pots in. And of course it might rain!

Garden Organic members have online access to our factsheets:

• Water in the Organic Garden
• Growing from seed

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• At the end of the month, all tender plants/seedlings can be planted out as long as there is no chance of frost. Northern counties may need to delay for a while longer. This long cold winter is still lingering in many areas. Wherever you live, take note of the weather reports, watch the temperatures and always have some fleece to hand in case of a chilly night. May temperatures can swing from +20C during the day to +1C (or less) on a clear starry night. Tender plants will be set back in such circumstances. A couple of sheets of newspaper, covered over with fleece, will be enough to keep them safe.

New seedlings can be scorched

Greenhouse

• May sun will scorch plants, especially little seedlings, very easily. Protect with shading material, or greenhouse shading paint, and open doors and vents during the day.
•  In the first week of May, transplant half-hardy seedlings from their seed trays, into pots. They will benefit from deeper pots and new compost. You can prick out plants singly, or in small clumps. Or even chop up a tray of seedlings into small squares and pot up in medium size pots.
• Plant up hanging baskets but leave in the greenhouse until the end of the month.
• Mid-May, start to harden off all your half-hardy annuals, and the hanging baskets. See details in General Tasks.
• Keep softwood cuttings out of direct sunlight while they are rooting. Place under staging and don’t allow to dry out. They can also be placed outside during the day, and brought into the greenhouse again at night.
• Remove, and dispose of, any dying foliage on sight. Disease prevention in a greenhouse relies on good hygiene
• Set up a water-saving watering system, such as drippers. This will be ideal for when you are away for a few days, and doesn’t waste water.

A wide range of watering systems is available from The Organic Gardening Catalogue.

• Keep a full can of water in the greenhouse so that it warms up and is not icy cold from the water butt or the hosepipe. Young plants need cosseting.
• Temperatures should be high enough by now to use all types of biological control. For red spider mite, use the predatory mite Phytoselius, for aphids use the tiny wasp, Aphidius, for sciarid fly use the predatory mite Hypoaspis, for white fly use the parasitic wasp Encarsia and for mealybug use Cryptolaemus beetles. All require 18-20°C for a couple of hours a day, so make sure you can achieve these temperatures before you buy.

Biological controls are available from the Organic Gardening Catalogue.

Garden Organic members have online access to our factsheet:

• Red spider mite
• Sciarid fly
• Aphids
  
• Greenhouse whitefly

Access to these factsheets requires members' password.
Find out more about Garden Organic membership.

Lawn and hedge care

•  Leave the box off the lawn mower, and let the clippings fly. They will rot speedily in warm weather, returning valuable nitrogen (70% of the lawn’s needs) to the growing grass. You'll save time and effort if you don't have to go back and forth emptying the mower box. In dry spells, don't cut the grass too short. A height of 3cm is ideal.
• Buying a new mower? Why not consider a 'mulching' or 'recycling' mower? These machines chop up the mowings very finely, then spread them evenly over the lawn. No more clumps of mowings walked into the house, and time saved not having to empty the grass box. If your lawn is quite small, why not buy a push mower instead of a motor one and save cost and fuel. Some good quality machines are available now.
• Recycling large quantities of grasss mowings:
  • Set up a dedicated compost bin. Layer up 10cm/4” grass clippings with the same depth of waste paper and cardboard. Scrumple junk mail, twist cardboard scraps and newspapers. Wet the paper well before adding grass clippings. No need to cover. This will take time to decompose and turning it occasionally would be beneficial.
  • Put a thin layer of mowings in your usual compost heap, but remember to add plenty of dry material too. Don’t overload the heap with grass.
  • Throw the mowings at the base of hedges where they will rot and return some goodness to the soil.
  • Use mowings to cover thick layers of newspapers to create a moisture-retaining mulch around trees and shrubs.

In extremis, dispose of via your green waste bin.

Be aware! Some lawn weedkillers contain a chemical that, while not damaging grass, binds to grass particles and will not break down easily. If grass clippings are added to the compost heap, or even composted separately, the weedkiller can still be present in the material after it is apparently completely decomposed. It will damage many vegetables and ornamental plants when used around the garden.

Organic gardeners should of course not use weedkillers on lawns, but readers of these pages might not all be organic gardeners!   

Find out more about this damaging weedkiller here and how you can help to improve matters

• Feed the lawn, if not already done. The Organic Gardening Catalogue has specific lawn feeds. Or use a general fertilizer, or even sieved garden compost if you have enough. Wait until rain is forecast before applying commercial lawn feed, and rake out thatch and moss beforehand.
• Reminder: Grass is a drought survivor. Even a lawn that has turned brown, and looks wrecked, will revive once temperatures drop and rain returns in autumn. That is assuming we’re going to have a sunny summer!

wind-scorched box
• Trim box hedges now. Cut out damaged sections that have been hit by the cold spell or succumbed to box blight. Use the trimmings as cuttings, and start some new plants that will fill any gaps once they are rooted.
• Symptoms of icy wind damage - box looks as if it’s been scorched,
• Symptoms of box blight - wispy grey fungus on the underside of the leaves and black streaky staining on the woody parts of the plant.
• If hedges are too bushy, check before cutting back as birds will be nesting now. If absolutely necessary, cut back individual branches just enough to reduce growth sufficiently. But wait until later in the year before undertaking any major hedge trimming.

Pond management

Plant around ponds
• Tadpoles and baby newts (newtpoles?) should be maturing and looking to leave the pond soon. Make sure there is a sloping side to your pond so they can get out.
• If your pond is surrounded by slabs or gravel, newly-emerged froglets will fry on sunbaked surfaces. If you can’t plant some sheltering plants (try trailing plants, such as nasturtiums, growing from a border, across the slabs, to the pond) to provide a safe, shady route from pond to garden. Or group some pots to provide a shady path for these babies. Grow some insect-attractant annuals in the pots for interest.
• Algae will probably build up as light levels increase, and temperatures rise. This should die down once pond plants bulk up. They shade the water, and use up nutrients, so algae are effectively starved. Ensure that your pond has two-thirds of its surface covered by plants of some sort to keep algae at bay.
• Water in the garden completes the perfect biodiversity circle. If you don’t have a suitable corner for a pond, why not set up a pond in a tub? There are plenty of attractive containers available – half barrels, ceramic or stone pots and so on. Choose a sunny corner for your container and plant up as you would a normal pond, making sure you have enough plants to keep algae at bay. And, equally necessary, is a ramp of some sort so that pond dwellers can climb out easily.
• Try growing watercress in your pond. It is a British native and, although it prefers slow moving water, it will also perform well in a pond. Simply buy some from the shops and place a couple of sprigs in a glass of water. Roots will appear in a few days. Once rooted, plant out in the margins of your pond, either in the water or the mud at the edge. This will give you a good crop throughout the summer months entirely for free. In mild winters watercress can survive and start up again the following spring.

• There are many other edible aquatics that you can grow in your pond.

Garden Organic members have online access to our factsheets:

• Edible aquatic plants.

• Setting up a pond
• Troubleshooting in the garden pond

Access to these factsheets requires members' password.
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What to plant in May

Bees are much in the news. Whatever happens at an international  level, we gardeners can help not only by keeping our gardens free from pesticides, but by providing nectar-rich flowers year-round. So choose, plant and grow, bee-useful plants this May. Here are some suggestions:

Winter flowering plants

Viburnum bodnantense and V. farreri – lovely shrubs, in flower from November until March, beautifully scented, providing a good food source even in the depths of winter.

Winter flowering heathers

Winter flowering heathers tolerate alkaline soil and will provide flowers from autumn until the following spring. Main colour range - white, pink,  red and purple/mauve. Recommended:  Erica x darleyensis ‘Lucie” (magenta flowers); E carnea ‘Springwood White’ (trailing white);  E vivellii(bronze foliage, purplish flowers); E x darleyensis ‘Darleydale’ (pinkish purple). Specialist nurseries will have plenty to choose from.

Mahonia japonica and M bealei. Long spikes of scented yellow flowers from autumn to spring. Tolerate most growing conditions.

Helleborus niger – the well-known ‘Christmas Rose’. Many colours, easily available and delightful through the winter months.

Plants for hot dry conditions.

Grey-leafed plants. Leaves look ‘grey’ as they are covered with a fine layer of hairs. This pale-coloured layer helps reflect the sun, and also traps a layer of humidity, reducing water loss. In some cases leaves also have a waxy coating, which also retains moisture. Many of these plants come from hot countries where rain hardly falls during the hot season, and watering is not practical. Try some of the following:

Perovskia atriplicifolia

Lavender and rosemary (adored by bees)  are well known, but how about Convolvulus cneorum, or Stachys lanata (Lamb’s ears).Helichrysum petiolare, Nepeta x faassenii (Catmint), Perovskia atriplicifolia (Russian sage), Santolina chamaecyparissus, Eryngium, Echinops, Osteospermum jucundum.  These are ideal plants for sunny gardens with dry, sandy soil. Helichrysum is often sold for hanging baskets/containers, but it grows quite happily in the open ground, meandering nicely across a border.

Useful annuals

Rudbeckia, Linum, Dimorphotheca, Calendula, Cosmos, Eschscholzia, Tagetes, Zinnia, Cerinthe major, Borage, Coriander (let it flower), Limnanthes douglasi (Poached egg plant), Nigella (Love-in-a-mist) Phacelia, These are all easy to grow, very attractive, excellent wildlife attractants, and require little watering once established. The Organic Gardening Catalogue has many choices of bee-useful flowers. Look for the bee symbol alongside the plant names.

Hanging baskets

A well-planted basket is a delight but they need daily watering, even when it’s raining. Last year was not too much of a problem (!), but should we get dryer conditions this year, here are some ideas to make sure your basket remains floriferous.

Water-saving ideas for baskets:

• Try to set up an automatic watering system that drips gently on a timer, keeping the plants moist, but water consumption at a minimum.
• As you prepare your basket, put an inner liner of plastic (bin liner will do) between the outer liner and the compost. Piece holes in it at regular intervals, then add compost and your plants. The plastic will retain some water, yet the holes will prevent waterlogging.
• When you water your basket, put a bucket underneath. Any excess water will be caught in the bucket, rather than just splash away, and can be used elsewhere.
• If your basket bakes in full sun, go for the sun lovers - pelargoniums (summer geraniums), petunias, blue Lobelia, Nemesia, and Verbena.
• Avoid planting with plants that prefer cooler conditions and therefore require a lot more water. Fuchsia, Impatiens (Busy Lizzie), white Lobelia and begonias all prefer slightly shady, moist situations.
• The Busy Lizzie downy mildew problem is still with us. Choose instead the New Guinea impatiens (Impatiens x hawkeri), resistant to this disease.
• Finally - large, or even medium size, containers can brighten up a garden, just as baskets do, yet they require far less watering.

Other plants for May
This is the best month for planting or dividing grasses and bamboos. These plants only grow new roots in late spring and early summer, so now and into June is when to plant. They tolerate dryness, as long as they are well-watered at first. But of course, wait until your soil is warm enough before planting.

Hakonechloa macra 'Aureola'

Milium effusum 'Aureum'

Deschampsia flexuosa 'Tatra Gold'

Miscanthus sinensis

• There are many grasses to choose from, from small tufty clumps to tall wavy, elegant grasses.
• There are grasses that are suitable for full shade or full sun and anywhere in between.

• For shade try Hakonechloa macra 'Aureola' also Milium effusum 'Aureum', found by E.A. Bowles at Birmingham Botanic Gardens. This is a beautiful delicate golden grass worth a place in any garden.
• For dry shade try Deschampsia flexuosa 'Tatra Gold' is a small lime green, clump forming grass ideal for dry shade.

• Grasses for sunny spots are easy to find, if you have the room try a large Miscanthus, these are generally tall upright grasses with feathery flowers. Try Miscanthus sinensis or if you like your grasses tall and tropical looking try Miscanthus x giganteus.

Make new plants

• Take softwood cuttings. All sorts of shrubs will be producing fresh growth now, perfect for propagation.
• Remove young, non-flowering shoots and, using a clean, sharp knife, remove the growing tips.
• Remove the lower leaves, leaving just a few leaves at the top of the cutting. Cut the stem just below a leaf node.
• Use a dibber or pencil to insert the cuttings into modules or pots of free draining compost.
• Keep pots in a shady part of the greenhouse, or on a north facing windowsill, until rooted (usually about 8 weeks).
• Cuttings will droop at first, so don’t allow to dry out, but don’t saturate. Once rooting starts, cuttings will perk up and new growth will be visible on the tips. At this point, pot up individually and allow to develop into sturdy young plants.
• If you buy in large specimen plants, such as fuchsias or pelargoniums, take softwood cuttings from them, before planting out. If there is no cuttings material right away, wait until they’ve put on some growth, then take cuttings before they flower. 
• Sow seeds of perennials, and spring-flowering biennials (such as pansies & wallflowers). Sow either in pots, or in a prepared seedbed. No need to use the greenhouse. Growing from seed is very good value, and of course your plants will be completely organic.
• 
  Pseudosasa japonica
  
  
  Phyllostachys nigra
  
  
  Phyllostachys aureosulcata f. aureocaulis
  
  
  Phyllostachys vivax f. aureocaulis
  
  
  Phyllostachys aureosulcata f. spectabilis
  Now is also the best time to dig and divide grasses and bamboos that have grown a little too big for their space.
• Gently lift a grass from the ground with a fork.
• Shake off any excess soil from the roots.
• Take a sharp knife and cut through to centre of the clump.
• Replant half immediately and water well.
• Divide the other half into as many pieces as you like and replant or pot up. Water well for the next few days until the grass is growing again.

Easy Perennials

This section gives you our suggestions of perennial plants that will look good or are looking good now, are easy to grow and fairly free of pest and disease, making them a good bet for an organic garden. All plants marked with a * indicates an Award of Garden Merit (AGM) from the RHS.

Feature on Bamboo

Popular plants, they are easy to find and architecturally useful in the garden. They may seem expensive to buy, as they are fairly difficult to propagate. Once planted and settled in they grow easily and seem to be entirely free of pest and disease.

• We'll start with the plainest of bamboos, Pseudosasa japonica* .It has plain, large green leaves and green stems and will grow in sun, shade or part both. Pseudosasa japonica is easy to find and one of the cheaper bamboos to buy. It is vigorous but not too invasive and ideal if you have a couple of square metres to fill.
• One of the most popular and most expensive bamboos is Phyllostachys nigra*, or the black bamboo. It has jet-black canes and deep green leaves. It is happy in sun or shade, and usually does not grow much in the first year or so after planting. It then takes off and will produce several new canes each year and bulk up nicely. It is not really invasive and seems to behave itself quite well, forming a lovely stand of tall upright black canes and delicate foliage.
• The yellow or golden bamboos are also very popular and their vibrant yellow canes add colour and structure to any garden. Phyllostachys aureosulcata f. aureocaulis* is a tall dense bamboo with pure yellow canes and small leaves. Again it does not seem to be too invasive and will form a good-sized stand in 5 years or so.
• Phyllostachys vivax f. aureocaulis* is very similar. It has thicker more knobbly stems than P. aureosulcata and is slightly more robust in its shape and form. Thus it requires a bit more room than your average bamboo.
• The final golden bamboo to recommend is the very stunning and striped stemmed Phyllostachys aureosulcata f. spectabilis*. This is one of the most sought after bamboos and is very expensive to buy, but worth every penny. The canes are incredibly striped green and yellow and sometimes a bit of a zigzag between each node, giving a truly exotic effect. It is fairly vigorous but seems to behave quite well and if it does out-grow its space, then friends would gladly accept offsets.

Greenfly symptoms

Pest and disease watch

• Check your plants regularly. Infestations can develop overnight - don't let this happen. In summer there may be 5,000,000,000 aphids in one hectare (2.4 acres) of garden. Puckered leaves are a good indication that greenfly (or some other colour aphid) are feeding on the undersides. They won't kill the plant, but will spoil the appearance. Small colonies of aphids can be wiped out easily between your fingers. Wear rubber gloves if squeamish.
• Rose Black Spot. Remove rose leaves, with the classic blotching of black spot, on sight. This material should be put into the dustbin.
  
  Vine weevil adult
• Vine weevil adults will be rampant now, and laying eggs. Treat any containers, including houseplants, with the biological control Steinernema kraussei – the soil will be warm enough now. Use non-drying grease round the legs of greenhouse staging, as adult weevils crawl and will lay eggs in any pots they find. They especially love fuchsias, succulents, heuchera, primulas.
Biological controls are available from The Organic Gardening Catalogue.
• Slugs and snails will be on the march. Use all controls at your disposal. The Organic Gardening Catalogue has an excellent range, including biological control against slugs. Don't apply the nematodes in dry weather - they need moist soil particles to swim through. Sadly, these useful little creatures are not as effective in heavy clay soil.
• Slug Stoppa granules are very effective as long as you put a thick and wide collar round susceptible plants. Be generous with these drying granules and the slug/snail brigade will not be able to reach your plants.
• Start nightly patrols to hand-pick slugs, snails and vine weevil.
• Wipe horse chestnut scale off acer branches. Use toothpicks to reach scale wedged in tiny cracks. They will breed and re-infest the tree unless cleared out.
• Handpick Solomon’s Seal sawfly larvae off on sight. If left, they will de-foliate plants, then drop to the soil to pupate and overwinter. Break the cycle by clearing off the larvae.
• Pick off bright red lily beetles, again to break the cycle. Daily checks should continue until the end of the month to be sure that all these beetles have been dealt with.
• Pyracantha stems infected with scab should be cut out and disposed of in the green waste bin.
• Remove affected stems and blooms from rhododendrons and azaleas affected by bud blast or gall.
• Viburnum beetle larvae will be active now, feeding on new foliage. Pick off any larvae (creamy yellow with black markings) that you can see, and trim back damaged foliage. It is worth putting down a thick membrane under and around damaged viburnum shrubs. The larvae drop down to pupate in the soil once they are fully fed, around late May – June. If you can prevent them reaching the soil, you’ll start to break the cycle.
  
  
  
  Ladybird eggs
  
  
  Hoverfly larvae
  
  
  Ladybird larvae
  
  
  Here come the beneficials!

Here come the predators!

• Beneficial insects, such as ladybirds and hoverflies, will soon arrive as the month progresses and the weather warms up. Look for ladybird eggs on plants near aphid colonies. Female ladybirds can lay over 1000 eggs, in batches of 20 - 50. If you're lucky, you'll see adults, larvae and eggs on the same plant.
• Take care! Hoverfly larvae can be mistaken for pests. If in doubt, leave well alone. They are voracious aphid eaters, so will be found in the middle of an aphid cluster. Adults feed on nectar, then lay their eggs near aphids so that when larvae hatch, they have a food source.
• Check very carefully before either squashing or spraying. There will be beneficial creatures around, munching happily on pests on the undersides of leaves. Insecticidal soap is just as damaging to them as it is to the pests.
• It’s not too late to sow seeds of predator-attracting plants. Eschscholzia (Californian Poppy) and Helichrysum (Strawflower) are ideal, and germinate quickly. All sorts of useful, predatory insects will feed from their nectar. Flowers of the Umbellifer family, such as carrots and fennel, are particularly popular. Their flowers will be used as a feeding station by hoverflies and ladybirds.

Garden Organic has produced a factsheet called Attracting Beneficial Insects (requires members' password) which lists the top ten insect friendly plants that every gardener should know about.

• Garden Organic members have online access to our factsheet:
  Attracting Beneficial Insects which lists the top ten insect friendly plants that every gardener should know about.
  
  Access to all the factsheets requires members' password.
  Find out more about Garden Organic membership.

  You can download the complete list of factsheets with order form (PDF document - 101Kb)

  Houseplant care

  • Water and feed regularly. Leafy plants require a high nitrogen feed, while flowering plants need more potash. The Organic Gardening Catalogue has a good range from which to choose.
  • Houseplants benefit from time outside. As long as no frost is forecast, they can go into a sunny sheltered corner at the end of the month, and benefit from fresh air, and gentle rain. But they hate cold winds. Be prepared to cover them up, or bring inside, if the weather turns grim.
  • Check before standing outside that the plant tolerates full sun. Monstera, Schefflera, some palms, Philodendron, Begonia, and Marantha are some common houseplants that prefer shady conditions. They will be damaged in full sun.
  • Keep a can of water either in the greenhouse, or indoors, so that you don’t use too cold water on your plants. Mains water will still be chilly from the winter and houseplants can be sensitive.
  • Keep watch for, and manage pests, just as you would do for all your other plants.

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