Newsletter 59 - April 2016
Ornamental plants
- Give your beds and borders a feed, particularly around roses, spring bulbs and young shrubs/trees. Remember that acid loving plants will need an ericaceous feed.
- Plant new perennials and finish off dividing summer flowering ones (eg delphiniums).
- Carry on sowing hardy annuals outside and planting out ones sown in the autumn.
- Think about how you’re going to support taller herbaceous perennials and start to put the supports in place as the new growth comes through.
- Deadhead your spring bulbs regularly. Cut back the foliage six weeks after the flowers have died down.
- Climbers and wall trained shrubs will be starting to shoot, so keep on top of tying them into their supports. Climbing rose stems should be tied in horizontally to get the best display.
- Prune winter flowering jasmines, hydrangeas, forsythias and flowering currants.
- Start to get rid of your winter bedding to make space for next month’s plantings.
- Now’s a good time to plant or move evergreen shrubs and trees (including planting new evergreen hedges).
- Plant out, or harden off, pots of dahlias, gladioli, calla lilies, arisaemas and tuberous begonias towards the end of the month when the risk of frost has passed.
- Outside it’s time to sow broad beans, summer cabbages, Brussels sprouts, early peas, calabrese, cauliflowers, sprouting broccoli, mizuna, leeks, beetroot, radishes, spring onions, sugar snap peas, mangetout, lettuces, rocket, turnips, kohlrabi, spinach, parsnips, Swiss chard, chicory, endives, carrots, onions and hardy herbs including parsley, chervil, fennel, dill and marjoram.
- Plant first early, second early and maincrop potatoes this month. Make sure the new shoots are covered with earth to protect them from frost.
- Onion sets, shallot sets, asparagus crowns and globe/Jerusalem artichokes can also be planted this month.
- Harvest the first overwintered spring onions and the last of the sprouting broccoli and Swiss chard.
- Keep weeding your veg patch so seedlings aren’t overwhelmed by weeds. Plant strawberries, figs and grapevines.
- In the greenhouse you can sow tomatoes, melons, cucumbers, sweetcorn, basil, coriander, aubergines, peppers, okra, squashes and courgettes.
- Mow your lawn fortnightly, or weekly if the weather is mild and it’s growing quicker than normal.
- Give your lawn a feed, though you may want to leave it until early May if you live in colder regions. You can also re-seed any dead patches in the lawn.
- It’s the start of the weeding season; removing weeds from borders now will stop them self seeding and causing a bigger problem later in the year.
- If you have slug/snail defences get them in place early this month!
- Purchase and pot up plug plants for summer ornamentals and vegetables.
- Ventilate your greenhouse on warm days in the morning, but shut them up again by mid afternoon to build up a bit of heat for overnight.
- Make sure you keep up with thinning out, pricking out, potting up and potting on your seedlings.
- Towards the end of April, unless the weather is unseasonably cold, you can start to harden off tender ornamental plants and greenhouse raised vegetables.
- Take advantage of warm days to stain woodwork in the garden, particularly where it will be covered with plants later in the year.
Narcissus 'Kiwi Sunset' is a wonderfully striking daffodil. The petals of its double flowers are yellow on the outside with whorls of ruffled orange and yellow at the centre.
It grows up to 65cm tall and flowers in mid spring. Find out more...
Peony grey mould blight affects the shoots, leaves, flowers and buds of peonies and tree peonies causing brown areas and grey, fuzzy mould.
Remove and destroy any affected parts immediately to reduce the risk of airborne spores spreading the disease. Find out more...
National Gardening Week focus on fitness
The RHS will be using this year's National Gardening Week (running from the 11th to 17th April) to focus on getting fit in the garden. RHS Gardens will be running health and fitness events including t'ai chi, outdoor healthy cookery demonstrations, buggy pushes for Mums and advice on how to use gardening to stay healthy.
Image courtesy of Marin at FreeDigitalPhotos.net
Creative Director appointed for London Flower Show
Garden designer Ann-Marie Powell has been named as the Creative Director for the inaugural London Flower Show. She will oversee the show's design and 'personality', working closely with organisers Live Industry.
The show will be held from the 8th to the 11th September this year at the National Trust's Osterley House and Park, a Georgian country estate in Isleworth, Middlesex.
New book lists the plants you must grow before you die!
A new gardening book, published by Octopus, purports to list the 1001 plants that you must grow before you die. Edited by Liz Dobbs, the book showcases flowers, trees and herbs which have been selected by garden writers and plant lovers on the basis of plant awards, trials and feedback from gardeners.
A bit of botany - parts of a leaf
As well as providing a variety of colours and textures for our gardens, leaves play a critical role in the survival of all plants. They are a plant's engine room, powering growth and adapting themselves to optimise energy production in some of the world's most inhospitable climates. Here we take a look at the botany of leaves and why our gardens couldn't exist without them.
Parts of a leaf
These are the basic elements of a dicotyledon* leaf:
Petiole
This is the small stalk which attaches the leaf to its stem. Some leaves attach directly (without petioles) and are called 'sessile' leaves.
Lamina
The main portion of the leaf is called the lamina, the edges of which are referred to as the 'margin' of the leaf. The lamina is the main area for energy production. Its cells are packed full of chloroplasts, which contain a green pigment called chlorophyll and carry out photosynthesis. This process uses sunlight to convert water and carbon dioxide into sugars, which power all the plant's growth.
Midrib and veins
The midrib (through the centre of the leaf) and veins (which extend from the midrib) are part of the plant's transportation system. They contain xylem vessels which carry water and dissolved nutrients up from the plant's roots (the water is used in photosynthesis), and phloem vessels which transport the sugars produced by photosynthesis from the leaf to other parts of the plant. The phloem tubes tend to run on the underside of leaves, which is why aphid infestations are often found underneath leaves as the pests suck on the phloem's sugary contents.
Stomata
These are tiny pores on the underside of the leaf which allow gases to enter and leave the leaf. This includes allowing carbon dioxide to enter the leaf and be absorbed for use in photosynthesis, and releasing excess water as vapour. In drought conditions the stomata will close to retain water within the plant - this is a short term survival strategy as the plant can't photosynthesise with the stomata shut and therefore will be unable to produce any further energy.
Other types of leaves
Monocotyledon leaves
* The leaf shown above is a dicotyledon leaf, which means that the plant it comes from produces two 'seed' leaves when it germinates, and its 'true' (adult) leaves have a spreading network of veins originating from the midrib. A monocotyledon only has one 'seed' leaf and its 'true' leaves have veins which run along the length of the leaf parallel to the midrib. Monocotyledon leaves are also all sessile. Grasses and bulbous plants are monocotyledons.
Conifer leaves
Conifer leaves, for example pine needles, have a thick 'cuticle' layer around the leaf with the stomata sunk below the surface, in order to survive in dry conditions. The phloem and xylem vessels run through the centre of each needle and it is believed that cells surrounding them transfuse water and sugars between the vessels and the photosynthetic cells nearer the leaf's surface.
Leaf adaptations
These are a few of the ways in which leaves have adapted to survive different environmental conditions:
Spines
In dry environments plants such as cacti have developed spines, which reduce water loss and also protect the plant from grazing animals.
Tendrils
Plants such as clematis and sweet peas have adapted leaves which twine around anything they touch to help the plant climb up and reach more sunlight.
Hairs
Leaves with hairs, for example lavenders, generally originate from hot climates. The hairs help to maintain the humidity around the leaf's surface in order to reduce water loss.
What's on this month
Walk off some of those Easter eggs at April's gardening events::
- 1st & 2nd April - RHS London Spring Plant Extravaganza, RHS Horticultural Halls, London.
- 2nd April - Plant Hunters' Fair, National Memorial Arboretum, Alrewas, Staffordshire.
- 3rd April - Plant Hunters' Fair, Ness Botanic Gardens, University of Liverpool, Ness, Cheshire.
- 9th & 10th April - Newbury Garden Show, Newbury Showground, Thatcham, Berkshire.
- 10th April - Spring Fling Plant Fair, Great Comp Garden, Sevenoaks, Kent.
- 15th to 17th April - RHS Flower Show Cardiff, Bute Park, Cardiff.
- 17th April - Secret Tenants; Microbes Living In Our Plants Talk, Cambridge University Botanic Garden, Cambridge.
- 22nd to 24th April - Newark Garden Show, Newark Showground, Newark, Nottinghamshire.
- 22nd April to 7th May - Tulip Festival, Pashley Manor Gardens, Ticehurst, East Sussex.
- 27th April - Great Spring Garden Event, Newport House, Almeley, Herefordshire.
- 29th & 30th April - Toby's Garden Festival, Powderham Castle, Kenton, Devon.