Garden Notes for April.
April is the time to get seeds going where you can give them a bit of warmth (for the chill evenings) and shelter. Sow tomatoes for outdoor growing; complete your sowings of half-hardy annuals (nicotiniana, mimulus, and antirrhinum for example).
Complete sowings of early potatoes. It is also time to sow celery for planting out in June (if you have been able to solve the problem of slugs!). A word of warning, metaldehyde (the blue slug pellets) are being banned in 2019 and will not be available from shops in future. Pellets based on ferric phosphate are an alternative. As always good hygiene, strong plants and a gardener’s eye to spot infestations are the best alternatives.
Keep up fortnightly sowings of lettuce in order to maintain a succession. Radishes can be sown. Soil should be pulled up on either side of broad beans to help keep them stable. Winter greens such as January King, Savoy cabbage and broccoli should all be sown from the middle of the month onwards.
As daffodil and other bulbs finish flowering remove the dead flowers as this prevents seed formation and diverts more energy into the growth of the bulbs.
If you want to grow exhibition size carrots, one tip is to drill the seed in small clumps along a given row with about 15 cm spacing. When the seedlings develop carefully pull out the excess and just leave a single plant to grow. That way they will grow long and straight without getting tangled in the roots of other carrots.
In the last week of April when the weather (hopefully) is warming up those of you with water gardens can start to plant up water lilies and other kinds of the hardier aquatic plants.
Do remember that early morning frosts are a real danger all through April and May, it is not until June, and even then it can be a bit dicey for the first week! that it is safe to put out any vulnerable plants – unless you can protect them at night.
Leave a can of water in the greenhouse to warm up before you water, this will reduce plants getting a shock from icy cold water. If you are sowing fine seeds (like nicotinia) – water the compost first. This avoids washing the seed deep into it.
Divide chives or mint if they are crowded (dispose of the roots carefully, they are invasive). You should finish planting main crop potatoes, and earth up any early growth. Frost is still a clear and present danger!
In unheated greenhouses sow Brussels sprouts, calabrese, summer cauliflower, kale and lettuce. In outdoor beds you can sow broad bean, beetroot, early carrots, chard, kohl rabi, parsnips, peas, radish, spinach, spring onion and turnips. Plant out onion sets. Peas can be started in a length of guttering in the greenhouse. When the seedlings are ready to go out, the compost will be held together by their roots and the whole row can then be slid into position.