Harden off young plants
Plants raised indoors should be moved outside during warm days and then back in again at night in order to gradually accustom them to lower temperatures. Cold frames or cloches are good halfway houses; they can be opened during the day and closed at night.
Tender young seedlings should start to go outside during the day in order to harden them off before planting out.
Continue preparing seedbeds
Rake over the soil, break up any large clods of earth, and weed thoroughly in preparation for sowing seeds or planting out new seedlings.
Prick out seedlings
Once young seedlings grown in trays or modules have developed a couple of leaves, move them in to individual pots or larger modules. This is called “pricking out”. Use a dibber or a pencil to lever them very gently out of the soil, taking care not to damage their delicate roots. Always handle seedlings by the leaves, not the stem. Once replanted, they will develop their own root system without crowding or competition from neighbours.
Pot on growing plants
Keep an eye on the development of seedlings growing in pots. If it’s still too early to plant them out, they may become “pot-bound” and their roots will be constricted. Tomatoes, in particular, are prone to outgrowing their pots. Simply re-plant them in larger pots until they can go out into the ground.
Water and weed
Water newly planted seedlings regularly. Little and often is better than a deluge once a week. Weed thoroughly, too, in order to remove any competition from young seedlings.
Protect against frosts
Sharp frosts can damage growing plants, so protect them with cloches or fleece. Peaches, apricots, and nectarines in blossom are particularly at risk and need covering with fleece or polythene sheets.
Put up peasticks
Peas are natural sprawlers and need supports for their tendrils to twine around in order to keep themselves off the ground. Hazel or birch peasticks are ideal, but chicken wire or plastic mesh can also be used. Whichever you choose, put them up now, before plants get established.
Build cane supports for climbing beans
It’s a good idea to erect supports for beans now, while the ground is still soft enough to push in canes or stakes easily. Traditionally, supports take the form of wigwams of double rows crossed over at the top. Use strong canes and thick twine or wire to withstand winds and support the weight at the peak of the harvest.
Remove rhubarb cloches
Cloches should come off for good this month. Once you’ve harvested the last of the blanched stems leave the plant to grow without cutting any more.
Earth up new potatoes
Draw soil up in ridges or mounds around potato plants in order to ensure that the tubers remain underground. If they are exposed to light, they turn green and can become poisonous.
Earth up potatoes as soon as the foliage starts to develop. It will protect them from frost as well as keeping the tubers covered.
Feed blackcurrants and blackberries
Apply a small quantity of high-nitrogen feed plus a generous helping of a blood, fish, and bone fertilizer.
Weed raspberry and blackberry canes
Keep weeds down at this early stage. The larger they get the more they compete with the new growth of your fruit and the harder they will be to remove.
Protect and hand-pollinate apricots, peaches, and nectarines
In a late spring, you may still have to cover trees with fleece or polythene to protect the flowers from frost damage – and possibly hand-pollinate flowers, too.
Prune cherry and plum trees
Once their leaf buds have opened, it should be safe to prune cherries and plums, as well as trained apricots, peaches, and nectarines. If you prune them earlier in the year, before the trees are actively growing, wounds heal slowly and you risk attack by the fungus that causes silver leaf.
Pull up brassica stumps
Remove any roots of winter cabbages, cauliflowers, and Brussels sprouts as soon as you’ve finished harvesting them. If you leave them in the ground, you risk a build-up of disease. Burn them or pulverize them with a hammer before composting them.
Take offsets of globe artichokes
Propagate artichokes by cutting “offsets” – new sideshoots or suckers with a short length of root - from the base of an established plant. Re-plant them, trim the leaves, and water them well.
Propagate herbs
Dig up, divide, and re-plant clumps of chives, lovage, mint, and marjoram. And propagate thyme by layering – pegging long stems from the parent plant into pots until roots develop and new plants can be detached.
Cover and feed strawberries
Keep cloches in place over strawberry plants in order to stimulate them into flowering so they produce a crop as early as possible. Remove the cloches during the day to allow insects to pollinate them. A sprinkling of sulphate of potash or a liquid feed of tomato fertilizer won’t hurt either.
Pick flowers off new strawberries
Remove the blossom from any new, young summer-fruiting strawberry plants you put in last autumn or this spring. You don’t want them to crop in their first year.
Pest and disease watch
Vegetables
Slugs
Flea beetles
Cabbage caterpillars
Cabbage root fly
Pigeons
Fruit
AphidsBig bud mite
Brown rot
Canker
Scab
Pear midge
Sawfly caterpillars
Bullfinches