Garden notes for May 2021
There is so much preparation to be done in May that it is easy to get carried away and be tempted to plant out too early. Garden Centres love this, as you will almost always have to go back and buy replacements for the plants that have died from the unpredictable ground and air frosts that can strike at any time during May.
One plant that can be put out, provided it is in a reasonably sheltered spot, is the outdoor flowering chrysanthemum. Possibly in this day of minimalism, stripped wood floors and stark furniture, the chrysanthemum may be regarded as being too gaudy. I love them. With care they reward you with so many beautiful flowers when everyone else is just going over. So plant these beauties now, make sure to plant them firmly and to make certain that the ball of soil rests at the bottom of the hole you have dug to put it in. Put a stake with each plant
Early Brussels sprouts can be planted out, and it is these that usually produce the best sprouts. Make sure to give them space, just under a metre (3′ in the old days), this way you will get a better crop. The space need not be wasted as you can inter-crop with early hearting cabbage, or early cauliflowers that will be harvested before the sprouts take up all the room. In May you should keeping sowing small quantities of lettuce for successional cropping. As the daytime temperatures increase in the summer it is more difficult to get good germination. It may be wise to invest in John Innes sowing compost. It is much more expensive than ordinary multi-purpose compost but you only have to use a small amount to start the seedlings and germination is considerably enhanced.
Start hardening off all those bedding plants you have bought from the internet or garden centre, by keeping them under a cold frame, or putting them out during the day and putting them back under shelter at night. Keep an eye out for watering, it is easy for them to become dried out in patches, especially if there is a wind blowing. Equally, do not over water, which can be just as bad, if not worse.
May is the time to sow hardy biennials – such as Sweet William, Canterbury bells, and Wallflowers. Sowing runner beans and French beans at the start of the month under glass gives them a good start and helps protect the young plant from the ravishes of slugs and snails. Don’t forget to sow the marrows and zuccini at the start of the month.
As alpine plants in the rock garden finish flowering, trim back the growth to keep the plants neat and compact. By doing this you will encourage them to make good growth for flowering next spring. In the same way flowering shrubs like philadelphus, deutzias and escallonias can be pruned as soon as their flowers fade to encourage new growth.