16:30 - 13 September 2010
August is a busy month in the greenhouse and yet it is also the time of year that many of gardeners choose to go on holiday. If you are only away for a few days you can usually set your greenhouse up to be self sufficient, any longer and you need to employ the services of a helpful friend or neighbour. Tomatoes, aubergines, cucumbers and peppers are all cropping their hearts out and need a constant supply of water and nutrients. They also need plenty of care and attention.
Ventilate, ventilate, ventilate. It’s essential to keep a good airflow through the greenhouse in hot weather. Keep the windows and doors open and use sheets of mesh or wire to keep out unwanted visitors.
Pinch out the tips of tomato plants when five trusses of fruit have set, this diverts the energy of the plants into the developing fruits and also keeps the plants in check.
Continue to tie in and support tomato plants, peppers, cucumbers, aubergines and melons as they develop, especially as fruit starts to swell or they will quickly topple over and be damaged.
Feed tomatoes, peppers, aubergines and other fruiting plants with a quality tomato feed for great results. Don’t allow tomato plants to dry out. Stress, inconsistent watering and a lack of calcium can lead to split fruits and Blossom End Rot. Choose a feed that contains vital trace elements to reduce the risk of this disfiguring disease.
Sow a late crop of your favourite vegetables in a deep growing bag or planter.
Continue to harvest developing crops in the greenhouse as soon as they are ready, this will encourage a constant supply and also improve the quality of the crop.
Pinch out the plant tips of cucumbers and melons.
Remove any yellowing leaves from the base of your tomato plants. This allows more light in to ripen the fruit. Do not remove leaves above developing or ripening fruit trusses.
Keep an eye on greenhouse grapes that may be showing signs of mildew, especially in very warm weather. Spray them with water daily if possible and if the problem is bad, prune out affected growth. Keep the air flow within and around the plant as good as possible, remove overcrowded leaves and thin heavy bunches of grapes by removing every third grape.
Sow spring cabbages now into pots and modules ready for planting out in September and October.
Keep the salad season going as long as possible and continue to sow lettuce, salad onions and even radishes. Look out for reliable winter lettuces that can be grown under cloches into the winter.
Deter an invasion of vine weevils in your pots and containers by applying the nematode based biological control to all your tubs, pots and containers, but especially those with Fuchsias, Begonias, Busy Lizzies and Pelargoniums. This will keep the compost around your containerised plants free from these voracious pests.
Gardeners are often encouraged to make very early sowings of flowers and vegetables for early crops. But there’s a lot to be said for sowing some seeds later in the season so that they flower into the autumn and extend the season. Check your seed packets and make some later sowings so that you have a continuous supply of plants to replace those that may now be past their best.
Sow hardy biennials such as Wallflowers, Foxgloves and Sweet William into small pots containing Multi-Purpose Compost with added John Innes. Keep them in a frost-free greenhouse or cold frame to germinate and grow on. Although they will not flower this year, they will produce strong healthy blooms next spring and summer.
Sow hardy annuals such as Nasturtiums, Calendula, Californian Poppies, Sunflowers, Cornflowers, Virginian Stocks, Poppies and wildflower mixtures into pots of seed compost, water gently and then sprinkle the seed thinly on top. Cover over with more compost and keep in a well-ventilated greenhouse or cold frame.
Sow half-hardy annuals and half-hardy perennials into pots of seed compost in the greenhouse. Good ones to try are Antirrhinum, Begonia, Coreopsis, Cosmos, Pelargonium, Impatiens, Ipomoea, Marigold, Nicotiana, Petunia and Penstemon.
Take semi ripe cuttings from shrubs and roses. Choose stems that have started to ripen but are not woody and tough. Good plants to propagate at this time include Hebes, Rosemary, Weigela, Hydrangea, Pieris, Buddleia and Pyracantha.
Take stem cuttings of climbers such as Ornamental vines, Summer Jasmine. Climbing Hydrangea and Kiwi (actinidia). Root them in pots of compost, and place them in a sheltered cold frame or a shady corner of the greenhouse.
Take stem and tip cuttings of established fuchsias and geraniums so that you have plenty of plants for next season.
