As I write in mid-April, the vegetables seeds I sowed in March have just begun to germinate. I have needed to water them, though, because we have not had any appreciable rainfall since then. If this continues it will mean that watering will, once again, be at the top of our list of priorities (provided there isn’t a hosepipe ban). Wherever possible, water in the evening so that loss from evaporation is reduced. It is best to water plants thoroughly once a week rather than do frequent light watering although plants in containers may well need daily watering. Although time consuming, it is more economical to use a hose to put water exactly where it is needed rather than using a sprinkler . If you have acid-loving plants keep rain water in buts for them as tap water is alkaline and will not suit them. The lack of rain is a problem but a happy side-effect is the absence of damage by slugs and snails.
If you grow vegetables, there will be a lot to do in May. You will probably have made some outdoor sowings by now but maintain successional sowings to prolong the harvesting season. The best way to have a continuous supply of lettuce is to sow a few seeds every fortnight. Successional sowing requires some discipline and it may be helpful to make a diary note of when it is due. This also applies to liquid fertiliser when, say, weekly or 10 day application may be recommended. French beans and runner beans, sweet corn and courgettes started under glass should not be planted out until mid May to avoid frost damage. Outdoor sowings can be made from now on. For runner beans grown in a row dig a double trench two feet apart (60cm) and mix the soil with garden compost before setting up the supports. I grow cucumber and tomatoes in a cold greenhouse but they can, of course be grown outside. I find a couple of cucumber plants are sufficient for two of us and I buy plants from a nursery as a packet of seed costs nearly as much as a couple of bought plants. As always, weeds in the vegetable plot need to be controlled and this is best done with frequent hoeing rather than an occasional blitz on well-grown weeds.
May is the month for planting out annual bedding in containers or borders. Here again, don’t plant them out until the danger of frost has passed. Keep them well watered and remember also that roses and clematis need generous watering. Give roses an appropriate fertiliser a couple of times in the growing season but clematis benefit from frequent feeding with liquid fertiliser such as tomato fertiliser or all purpose Miracle Gro.
Dahlias are becoming fashionable again and they do provide a long season of colour; repaying attention with watering, feeding, nipping out and dead-heading. If plants have been in the ground all winter they may well be showing growth above ground by now and this will need protection from frost until well on in the month. Either cover the new growth with soil or cover foliage with horticultural fleece when frost threatens. Pay attention to weather forecasts. Stake plants and restrict them to one or two main stems, cutting out other shoots (which can be used as cuttings) and nipping out the top of the of the shoots selected as main stems once they are 4 or 5 inches high (10/13cm). When flower buds start forming, the largest flowers are obtained by nipping out the pair of buds immediately below the main one at the top of each shoot.
It is a bit late now but you can still divide clumps of perennial flowers to cut out weakened centres or increase your stock. Lift the clump with a fork and then split by hand, teasing out the roots or use two forks back to back to prise them apart. Fleshy roots, like hostas, can be divided by cutting with a spade. Take the opportunity of lifting a clump to incorporate garden compost or well-rotted manure in the soil where the divided plants will be repositioned.