May sees the seasons changing again, with spring rolling into early summer. It is a glorious month, greener than any other, with potential still in the air with a danger of being overwhelmed with all the growth in the garden.
Keep a watch on tomatoes
Tomatoes originate from South America and suffer as soon as temperatures drop below 10°C. Keep them under cover until you can be sure that the weather is warm enough to plant them outside, and then find the warmest spot to give them all the help they can get. If you are growing in the ground out of doors, keep well away from the potatoes, as blight can travel from one to the next. Try to keep the plants in a position that is warm but with air movement, as the blight favours humidity. Bush varieties are great in pots on the terrace.
Get tough on weeds now
If there is one priority in the garden over the next few weeks it is weed control. The message should be zero tolerance on weeds until the ground covering foliage of perennials closes over to suppress seedlings. Little and often takes the monotony out of weeding, so set a half hour aside every time you garden
Try growing strawberries in hanging baskets
Everyone can have delicious strawberries by growing them in hanging baskets. You don’t need a large garden or allotment, just somewhere sunny to hang your baskets.
When growing strawberries in hanging baskets, the fruit hang down over the side of the basket which has two main advantages. Firstly, air can circulate around the fruit, keeping them dry, which will prevent mould and mildew forming, especially during wet summers, and secondly slugs and snails can’t reach the fruit.
Hanging baskets do not hold much soil (strawberries don’t mind this as they are shallow rooted), but it is important to keep the basket well watered, and the plants will need feeding. Once they have flowered, feed with a liquid tomato feed every couple of weeks. You can also incorporate a slow release granular feed into the compost at potting time, which will provide the plants with nutrients.
Planning ahead with beans
Pinch out the tops of the broad beans once the flowers are visible, as it helps to keep the black fly at bay. Keep the tops, as they are delicious steamed and dressed with a little olive oil and lemon. Wait until the end of the month to put in the French beans, and hold back until early June for the runners, as they need the heat to do well and will rot in ground that lies wet and cold. It is good to learn that most fast-growing annuals catch up if you get the timing right. Put your efforts into successional sowing of lettuce and salad leaves. Radish make great fillers between rows of slower-to-develop veggies.
Time for a lawn feed
Apply a spring lawn feed if you didn’t do it last month.
Repair thin or bare patches in the lawn or bald lawn edges before the end of the month.
If you have newly laid turf, don’t mow until it has rooted itself securely into the soil. If the grass has grown tall, raise the blades to the highest setting to start, gradually lowering the height over a couple of weeks.
A new lawn which has been grown from seed should be left for a while. Cut the tips of long tufts down with a pair of shears until the grass has made longer roots.
Planting out pumpkins and squashes
You can tell the new gardening season is well on its way when squash seeds spring into life. The young plants will need acclimatising to conditions outdoors before planting out. A couple of weeks before the last frosts are forecast place the plants outside for the day and bring them in at night. In the second week leave them out in a sheltered spot day and night. By the middle of the month it should be safe to plant them out.
Get ready to earth up
As soon as potatoes break through, earth them up. Coving up the foliage in an inverted trench may seem like rough treatment, but their tops will recover quickly – and keep the fleece handy. They need moisture, so water (wisely) if we have a dry period.
The tubers start to swell as the plants come to flower, but don't be tempted to harvest until the flower trusses are fully out.
Earthing up is not limited to potatoes. With brassicas especially top-heavy crops such as Brussels sprouts that must grow through the gales of the autumn and winter as it helps prevent damage from wind rot. Leeks, celery and florence fennel are all earthed up to blanch the developing stems or bulbs.
Be patient when it comes to mowing bulbs
There’s a temptation once the spring bulbs in your grass pass their best to mow over them. It’s neater and tidier. But this year try and be a bit more patient as it will reward you in the long run. Don't be tempted to mow off bulbs in grass until five to six weeks after the last flower. They need this time to replenish their energy and the wildlife will enjoy the long grass, so leave it to do its thing for a while yet, if you can. Overcrowded daffodils will flower less reliably. Now is an ideal time to lift, divide and re-plant.
Other tasks this month
- Harvest rhubarb, picking only a third of the total amount of stems.
- Protect crops from carrot fly by covering with horticultural fleece or enviromesh.
- Prune your penstemons now - cut all the old shoots back to the base provided there is new growth at the bottom of the plant. If there are no new shoots at the base, cut just above the lowest set of leaves
- Tie in your sweet peas with plant support rings to encourage them to climb.
- Prune spring-flowering shrubs after flowering.
- Cut back flowered shoots of choisya to promote a second flush of flowers in autumn.
- Trim lavender plants now, cutting off any old flower heads and about one inch of the current year's growth.