In your ornamental garden in April 2012

Contents

• General tasks
• Greenhouse
• Lawn and hedge care
• Pond management
• Ornamentals for April
• Pest watch
• Houseplant care

General tasks

• 
  Honeysuckle: Tie in honeysuckle
  stems as they start to grow
  Prune spring flowering shrubs such as forsythia and winter jasmine. Next year’s flowers will be produced on stems growing over the coming months, so cut back hard now to get the shape you want for next spring.
• Deadhead daffodils, but leave the leaves alone for 6 weeks after flowering. This gives the plants time to store food for next season’s display.
• Tie in honeysuckle, clematis and other climbers as new growth starts to sprout. Don’t let clematis become a tangled mass.
• On variegated plants, prune out shoots that have reverted to plain green. If left unchecked, they will eventually take over from the variegation.
• Hoe weeds as they emerge. Don’t let them seed. Chickweed can put out 2000 seeds per plant per season! As you hoe, make sure you don’t damage the emerging shoots of perennials.
• Perennials should be staked early so they can be tied in before they start to flop. You can make your own supports from prunings from around the garden
  
  

  Staked perennials: Stake & tie in perennials before they get too tall Maggi Brown

• 
  
  
  Grit mulch on containers
  Feed the soil. Use your homemade garden compost, or well-rotted manure, around established plants, and in planting holes when planting. Rate of use – compost: 1 standard garden bucket per sq m.  Manure: half that amount.
• Once soil is warm and still moist, mulch well, to a depth of 6cm/3ins. Use leafmould or municipal greenwaste compost if possible. Mulch materials are also now available commercially. This will suppress weeds and help retain moisture levels right through the summer months.
• If you want to plant more bulbs this autumn, mark the spots now with short bamboo canes. Sow some hardy annual seeds there for the time being, to hide the bare patches. In autumn, you’ll find it easy to remember where you want to plant the bulbs.
• Plant out sweet peas if they are tall enough. Provide support with twigs or string or pea netting.
• Top dress containers. Scrape the top 4cm/2ins of soil off, and replace with garden compost, or well-rotted manure. Finish off with a good layer of horticultural grit to retain moisture.

Greenhouse

Inside the Alitex glasshouse
at Garden Organic Ryton

• Make sure automatic vents are working properly, and open the door on sunny days. Temperatures will soar inside a closed greenhouse this month.
• Remove insulation and get ready to put up shading.
• Keep watch on seedlings and don’t allow them to dry out.
• Avoid fungal diseases by watering from below to avoid wetting foliage.
• Don’t water seedlings with cold water direct from the water butt or hosepipe. Keep a couple of cans filled and inside the greenhouse so the water is at the ambient temperature.
• Pot on dahlia and begonia tubers and pinch out tips of fuchsias and other half-hardy plants.
• Buy in ‘tot’ plants. They are inexpensive, and a wide range is readily available now. You can grow them on organically, and have a superb display all summer. Keep frost free. 
• 
  Tot plants before and after potting up
  Sow perennials in modules or small pots. Prick out once leaves are large enough to handle. Plant out when well-established. Some perennials may flower this year, others will take longer.

• Don’t dig peat!

  
  
  Choose seed and potting composts that don’t contain peat when buying your supplies this spring. Or make your own from basic garden ingredients.
  Go to our ‘I don’t dig peat’ website for d-i-y recipes, and ideas for buying peat free composts.

•  Top-dress any large potted plants. Scrape off 4cm/2ins of the old compost. Replace with garden compost, or well-rotted manure. Finally, cover over with a layer of horticultural grit.
• Pot on any half hardy and tender perennials. A mix of good garden compost and 20% grit is often ideal for this. If you grow agave or cacti then increase this to 40% grit.
• Divide half-hardy and tender perennials that have overwintered in warmth. Hedychium, Musa, Aspidistra, Agave and Aloe can be split now then kept well watered for a few weeks until you see active new growth.
• Pest populations usually start to increase dramatically now. Be vigilant and don’t allow infestations to build up. Use organic treatments, such as insecticidal soap, to control problems until the temperatures are warm enough for biological controls to be introduced.
• Once it’s warm enough, introduce biological controls in the greenhouse. Use the predatory mite Phytoselius to control red spider mite, the tiny wasp Aphidius for aphids and the predatory mite Hypoaspis for control of sciarid fly. You will have to wait until May to use other biological controls, as they require slightly higher temperatures to survive and thrive.
A wide range of biological controls is available from The Organic Gardening Catalogue.
See our factsheets on Glasshouse red spider mite and Aphids.

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

Lawn and hedge care

• 
  An organic lawn can be a
  great asset to your garden
• Grass is a drought survivor. Don’t waste precious water on your lawn. An hour with a sprinkler can use as much water as a family of four in one week! Keep the grass a bit longer – 3cm – and even if it starts to turn brown, it will survive. Once rain starts, the grass will spring up good as new again. Check out Garden Organic’s Ten Top Tips to avoid the tap
• Leave mowings on the lawn for worms to take down into the soil. Mowings can provide 70% of the nitrogen needs of the grass over the summer months.
• It’s time to feed the lawn if it needs it. Apply when soil is moist, or water well after application. Rake or brush in. Use one of the following:
• Garden compost or well-rotted, sieved farmyard manure:  a few handfuls per square metre
• Seaweed meal: 60-120g/sqm..
• Chase Lawn Fertiliser (spring treatment).

• If your lawn is filled with moss, now’s the time to address the situation. Moss is a symptom of an underlying problem.  Compaction, too-close mowing, acid conditions, heavy shade and damp conditions will trigger moss development. Identify the problem, then resolve it.
• Compaction – aerate the lawn now, and again in autumn. Brush in material such as leafmould, greenwaste, or even old potting compost. Do this annually from now on.
• Too-close mowing – raise the blades on the mower. Keep them 3cm up.
• Acid conditions - test your soil. Most garden centres sell pH testing kits these days. If the soil is very acid, aerate then brush dolomite limestone into the holes.
• Heavy shade and damp – not always easy to alter. But consider removing the grass entirely in these areas and replacing with plants that will tolerate these conditions.  Some grass varieties will tolerate shade.
• Start a new lawn from seed. Soil should be moist for sowing, and once sown, seed must be kept watered in dry spells. 

• Feed a hedge that is lacking in vigour  with a top dressing of garden compost or well-rotted manure. Alternatively use a feed such as Chase Organic All Purpose Fertiliser. Or mulch with lawn mowings.  They will release nitrogen as they break down.
Organic Lawn care products are available from The Organic Gardening Catalogue.

Pond management

Newt

Your pond may be a glorious wriggling mass of tadpoles by now. And if you have newts, they should appear now to mate. As they are shy, sit quietly and wait for them to surface to gulp air.

• Remove blanket weed on sight. It often builds up now as light levels and temperatures increase. This triggers algae growth in the pond.
• Have plenty of plants around the pond’s sides for moist shelter. This is essential if your pond is set in gravel. In hot weather, stones become bone dry and will fry baby frogs as they emerge for the first time.

Ornamentals to plant in April

This is the perfect time for planting. Soil and air temperatures are steadily rising, and rainfall is usually still adequate. Visit a good garden centre or a specialist nursery to find some of those lovely plants you have spent the winter reading about. Check out the NCCPG website for details of Specialist Plant Fairs.

• Look for plants that will attract bees, butterflies, and other valuable flying creatures. Bees in particular are under threat. Our gardens are needed to provide the plants that will help them survive. 

Check out the British Beekeepers Association website: www.bbka.org.uk for ways to make your garden bee friendly.
See our factsheet on Wildlife Gardening. Access to this factsheet requires members' password.
Find out more about Garden Organic membership.

• Hardy geraniums are superb plants and there is a variety for every location. They often flower for months on end and are magnets for nectar hungry wildlife.
• If you’ve started hardy annuals in seed trays or pots, once seedlings are large enough to handle, plant out in spots around the garden. Just chop up the trays of seedlings into small clumps and plant.
• Erysimum 'Bowles' Mauve' is easy to find and should flower from now until the New Year!
• Euphorbia griffithii 'Dixter' should be looking fabulous.
• Various small-flowered Viola are sweet and delicate, and there should be a good variety to choose from in garden centres. Look out for Viola 'Chelsea Girl' and Viola 'Little Liz' or the British native, Viola tricolour.

Make new plants

• There is still time to divide overgrown clumps of herbaceous perennials, as described in previous months. Water well after transplanting, and keep moist in dry spells.
• Don’t divide grasses or bamboos yet.
• Sow seeds, either direct for hardy annuals or into modules/small pots for hardy perennials. This is the very best way to sow your perennials, as root damage from pricking out is non-existent. Plants establish quickly and are easy to pot on or plant directly out.

Easy perennials

Clematis viticella


Clematis viticella 'Etoile Violette'


Clematis viticella 'Little Nell'


Clematis viticella 'Madame Julia Correvon'

Here we offer our suggestions of perennial plants that will look good, are easy to grow and fairly free of pest and disease. This makes them a good bet for an organic garden. All plants marked with a * indicates an Award of Garden Merit (AGM) from the RHS.
This month we look at Clematis viticella, a diverse species of Clematis with sweet, delicate flowers, bold splashes of colour and full double pompom heads - they really have one for everyone's taste. The viticellas are easy to buy, grow and are pretty much trouble free. They don’t as a rule suffer from clematis wilt. Grow them through early flowering shrubs such as forsythia or winter flowering viburnum. They offer lots of support and the clematis adds interest to an otherwise plain green shrub.

• The species Clematis viticella* is a beautiful simple plant, free flowering with delicate blue weeping flowers that, in time, open to a four petal flat star. Good for sun or part shade, it really earns its keep in any garden. Grows wild in southern Europe and western Asia.
• C. viticella 'Etoile Violette'* is an old French Clematis raised by M. Francisque Morel in 1885. It is deciduous and can, in time, grow to 3.5m (12ft). When happy, it will flower with a profusion of velvety, dark purple blooms with a light centre band to each petal. Grow through a Philadelphus coronaries 'Aureus'* for a stunning contrast in colour.
• Another real favourite is C. viticella 'Little Nell'. This gorgeous viticella has an interesting history. It was raised as a seedling by Morel and given to William Robinson and Ernest Markham at Gravetye Manor in Sussex in 1914. Markham named it after his wife Nell. It was finally introduced in 1939 by Jackman. C. viticella 'Little Nell' is not so little, making 6m (20ft) and is happy in sun or shade. When flowering, it is covered in hundreds of small white and pinky/violet flowers that are loved by people and bees alike. Good for cutting too.
• C. viticella 'Madame Julia Correvon'* is another viticella bred by Morel in 1900. It is a true red and has medium large flower of four velvety petals about 13cm (5in). The petals often recurve or twist at the tip giving an interesting feature. This stunning and bright clematis flowers from early summer to early autumn and is also happy growing in a large pot, making it ideal for the patio.
• Finally the best of the entire viticella group and, of course, raised by Morel in 1899. C. viticella 'Purpurea Plena Elegans'*. This Clematis is vigorous and tough, making upwards of 3-4m (12-15ft). It has maroon pompom flower heads, with petals opening from the centre that just keep coming and coming until it is simply a ball of open petals - absolutely stunning.

Pest watch

A frequent walk around the garden is not merely a delight, but you’ll notice problems at an early stage, when they are much easier to deal with.

• 
  
  
  Aphids of every hue will start to multiply this month. Check out honeysuckle and roses in particular. Squash colonies with your fingers, or spray with insecticidal soap. Take care when spraying. Although predators are still not out and about in great numbers, they are around. If in doubt, just squash (wear rubber gloves if squeamish).

• Check all containers for pupating vine weevils, especially where you’ve grown any fuchsias.  Larvae will be turning into adults now, and in their transition stage, they look like translucent woodlice. Rummage through the soil carefully or even turn out pots completely. Squash any larvae and pupating larvae you find. Adults are most active at night, so go out and check for any climbing around and into containers, particularly during warm weather.
  
  Notched leaves are a typical sign that adult weevils are about, eating the fresh growth and laying their eggs on the soil surface.

• In the greenhouse, a band of fruit tree grease round staging legs will prevent adult vine weevils from climbing up into plant pots.

• Viburnum beetle eggs overwinter in shoot tips. If your viburnum leaves were shredded last summer, prune out last year's young shoots to break the cycle. Dispose of in your green waste bin. All green waste is composted at high temperatures so pests and diseases are destroyed, but the waste is turned into useful compost.
• Slugs and snails will become very active this month. Most newly emerging shoots will be at risk. Act now - don't wait until plants have been sheared off to stumps.
  
• Destroy their egg clusters when noticed. Look for translucent milky spheres, usually laid in nooks and crannies in the soil, and down the sides of pots and containers.
• Put thick and wide collars of Slug Stoppa granules around delicate perennial shoots. Delphiniums in particular are at risk.
• Use all controls available. Don’t rely on just one method to deal with these hungry munchers.

• Check for hollyhock rust. If seen, pull up plants and put them in the green waste bin. Start afresh with new plants. Rust will infect plants from year to year, so it’s important to break the cycle.
  
  
  
  Dieback: Cut out dieback
  on shrubs and trees
  
  
  Poppy: Hoverflies love
  open-mouthed annuals
• Keep watch for bright red lily beetles. Look for them on fritillaries, Solomon’s Seal, as well as emerging lily shoots. Squash when seen, to break the life cycle.
• If your box plants show sign of die back, it could be box blight. Remove all affected stems and put them in the green waste bin.
• Cut out dieback on shrubs and trees. Acers in particular are prone to this problem. Cut back to a joint and into live wood.
• Check acer stems for horse chestnut scale. Look for white fluffy patches surrounding a brown centre. Scrape or wipe off with fingers. Use a toothpick to clear out scale lodged in narrow cracks.
• As hostas start to push out new shoots, protect from slug and snail attack. Use all methods available. Hostas grown in pots can be surrounded with a thick collar of Slug Stoppa granules.
• Encourage predatory wildlife into your garden. A log pile will shelter slug eating frogs, and beetles. Hoverfly and ladybird larvae will consume hundreds of aphids all summer long. Provide the conditions and they will come!

House plant care

As temperatures increase and light levels improve, houseplants will start growing strongly once more. It’s easy to keep them in tiptop condition.

• Feed from now until autumn.  Easy to use are fertilizer sticks from The Organic Gardening Catalogue, but there is a wide selection. Large leafy plants will need a high nitrogen feed, while flowering plants need something like a tomato feed, high in potash.
• Water when needed and preferably from beneath. Large leaves lose water fast, so hot weather means more frequent watering. If you lift the pot (if possible) you’ll soon feel if it’s light. Never let plants stand in water for longer than 10 minutes.
• On sunny days, plants relish time outside. Make sure they are suitable for full sunlight. Monstera (Swiss Cheese Plant) will scorch easily. Bring in once temperatures drop.
• Clean leaves that have become dusty during winter. Put in the bath and shower with tepid water. Drain well.
• Check plants for scale. Schefflera, (umbrella plant), Ficus benjamina (weeping fig) and Citrus are very susceptible. Wipe off when seen before they start breeding.
• Fatsia often are infested by red spider mite. They are tough plants and will be quite happy outside in a semi-shady corner. This should clear the spider mite over the summer, and you can bring the plant in again in the autumn.
• In a conservatory, use biological controls to keep mealy bug, aphids, whitefly, red spider mite and sciarid fly under control. Most of these predators require temperatures around 20C, and this month you should reach that on sunny days.

The Organic Gardening Catalogue has biological controls for most houseplant pests.

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