May Lawn Jobs
In May's warm weather the grass really starts to grow and needs cutting at least once a week. You should not need to water the grass, just keep it trimmed at the edges and around trees. Avoid cutting the grass shorter than 2 inches unless you have a putting green lawn. Longer grass withstands wear and drought much better than short grass.
You can apply a lawn fertilizer and weed killer this month, just follow the directions that come with the product. Apply the fertilizer a couple of days after you have cut the grass, ideally when you are expecting rain the next day. (If it dose not rain then you will need to water the fertilizer in).
Leave for 5-7 days after applying the fertilizer before you cut the grass again.
You might not want your grass to grow any faster, but if you want it healthier and greener then you will have to use fertilizer.
Hedges in May
Whether you are trying to encourage hedges to grow taller or to keep tidy hedges tidy, you will need to cut them in May. Just trim off any straggly branches or twigs. Do not cut hawthorn or similar wild hedges because there will be birds nesting in them. Hawthorn will not have put on a lot of growth this early in the season anyway.
Either compost your hedge trimmings or use them as cuttings to grow more hedge plants from, just stick the trimmings in a bucket of used compost. If they root, then plant them in the ground in a spare corner until they are a year old and a bit bigger.
Roses in May
Watch for the first signs of black spot, especially if May is damp. Spray with liquid copper as a preventative measure in any case. If your roses are infected then cut off any affected parts and burn them. Do not leave them on the ground or put them in the compost heap, because the infection will survive and spread when you apply the compost.
Black spot is about the worst thing that can happen to your roses. It first appears as black spots on leaves, then as it spreads like wildfire the leaves turn black and sticky. Flower production stops altogether. Liquid copper fungicide gets into the sap and prevents any new growth being affected.
If you notice a few greenfly near the flower buds, do not get the insecticide out. When the buttercups flower in a few weeks time the hoverflies will breed and wipe out your greenfly infestation.
I have about 100 roses and can never find a single greenfly and I have not used insecticides since planting them four years ago. There are lots of blue tits and lots of hoverflies in the garden. I have a few patches like behind the shed where I allow buttercups to go mad.
Soft fruit in May
Make sure your soft fruit gets plenty of water, or the bushes will not set flowers and you will get no fruit. You will have to put netting over the redcurrants at the end of May, well before the currants are ripe if you want to eat them rather than feed the birds. Birds love these and will eat them as soon as they are half ripe.
May Vegetable Jobs
If you have not yet sown any leeks you can still sow them in May, just sprinkle the seeds into a bucket of compost and cover lightly.
It is time to transplant any peas that you sowed in pots or troughs last month into the ground. Put a few twiggy sticks in amongst the transplanted peas so that they have support to grow upwards.
Sow Brussels sprouts and broccoli seeds in seed trays or troughs. Troughs or buckets are better if you are forgetful about watering. Seed trays especially, must be watered every day. Add a handful of garden lime to the compost when planting, though there should be some lime in general purpose compost anyway.
Harden off and plant out your tomatoes, whether into pots, grow bags or the garden soil is up to you, but plant them out. Harden them off by standing them outside during the day in their seed trays and bringing them in at night for a week. After a week of hardening off most will survive. Cover with horticultural fleece at night if the temperature is expected to fall below 5 Celsius, or 41 Fahrenheit.
Sow runner beans and French beans. At the start of the month in pots of warm compost on window sills inside the house. At the end of May these can be planted in the ground, where they are to grow.
Climbing beans are not suitable for containers because the wind catches them and they will blow over, though if you have concrete planters they will suit very well. You can plant low growing French beans in containers.
Shrubs – May Jobs
Most shrubs will be in bud and it is a bit early to take cuttings in May
Climbers – May Jobs
Thread your clematis stems behind any supporting trellis, being careful not to damage any flower buds.
Annuals – May Jobs
May is an extremely busy month for the annual flower border. You still have time to sow all your favorite annual flowers, either directly into the ground or into seed trays.
If you sow seeds directly into the ground it must be weed free, otherwise the young seedlings will be hoed out along with the weeds. Plant seeds or seedlings in the ground about 8 inches apart to give you room to hoe between them. Plant both in straight lines, it makes hoeing easier and as the plants grow you will not notice the lines at all.
If your beds are weedy, just plant the annuals' seeds into compartmented seed trays and transplant them when they have three or four pairs of leaves.
Biennials – May Jobs
Plant out any hollyhocks that have survived the slugs. Put eight foot canes next to the young plants for support, tying them in as necessary.