May is an important month in the gardening calendar. It’s the time of the Chelsea Flower Show (online for the first time this year due to Covid-19), where new and established garden designers usually take to the stage to ‘wow’ their audiences and, hopefully, win awards. As a gardener, we get to see what’s in, what’s not, and what we would like to grow, both in the garden and on the vegetable patch.
May is also the time for the ‘Chelsea Chop’, when we can take our perennials, such as Phlox, Sedums and Heleniums, and prune them, or reduce them by 50%. This helps create a bushier plant with more blooms. Also, if you have a border of perennials which you want to flower simultaneously, then the Chelsea Chop is often the answer as it can help delay flowering.
By now, the ground is warming up, enabling us to sow and plant-out directly into the soil. Plants you’ve been growing in the greenhouse can be hardened-off and planted into their final growing positions. Many vegetables, grown from seed, can also be brought out from the polytunnel, planted into their final positions, and then protected with either fleece or netting. But bear in mind that May can be a fickle month. Your plot can be basking in sunshine one week, and water-logged the next. So, keep your eye on the weather forecast, keep horticultural fleece handy, and be prepared to act if the weather takes a turn for the worse.
May is a great month to be a gardener. So, while the sun shining, get out there and make something grow.
In the flower garden
Now that they’ve flowered and the foliage has died back, this is the time to lift and divide your spring bulbs. Before your summer plants dominate the flowerbeds, think about where you want to see your spring bulbs to appear next year, and get them into the ground.
With the chance of frost now waning, towards the end of the month you should think about getting your summer bedding plants into the ground, hanging baskets, pots or containers. Once planted, ensure you give them a regular water and a regular liquid feed to encourage large, long-lasting blooms. If you’re using containers, or hanging baskets, consider planting them up with water-retaining granules.
The Dahlia tubers potted on back in early spring should now be producing sufficient foliage for them to be hardened off, and planted into their final growing positions. If you’ve just bought tubers, depending on where you are in the country, the ground could be warm enough for them to be directly planted into the soil. Remember, plants are now growing quickly, so highlight where you planted them with a label or bamboo cane.
Pests, such as the lily beetle and greenfly, will be making an appearance. Check all plant foliage regularly, and dispose of any unwanted visitors. For slugs and snails, a good time to go out and check is first thing in the morning, around dusk, or after any rainfall.
Grass will be thriving, so mow your lawn weekly. Also, trim edging and remove any weeds. If you do decide to use chemicals, always consider who uses the lawn, and where the liquid runs off to. You wouldn’t want to damage a flower bed, and you definitely wouldn’t want to harm a family member or pet.
The garden is putting on growth daily. However, with the risk of a late frost, it’s good to keep horticultural fleece handy. For your climbers, such as sweet peas, roses and perennials, ensure they are staked and tied into a support. You wouldn’t want all your months of hard work to be damaged by a single bout of bad weather.
Weeds will be competing with your plants for both water and nutrients. Remove immediately, or they could strangle and starve your plants.
Over the next few months, temperatures will continue to rise, so get into a regular watering regime with all plants, especially ones grown in pots, containers and hanging baskets. A regular liquid feed is also advisable.
On the veg patch
By now, plants such as strawberries, gooseberries and currants will be developing fruit, so they will need all the nutrients they can get. Keep the area free of weeds, and water regularly. If you can spot growing fruit, so can pests. Check plants regularly for pests, such as sawfly and aphids, dispose of them and net the plants. If you’ve been growing strawberries on open plots, or raised bed, then place dry straw around the plants to protect fruit from rotting, and help suppress weeds. Ensure you water at the base of the plant only, not overhead, as this will encourage mildew.
Stake broad beans with canes and lengths of string, as this will take the weight of developing pods, and prevent wind damage. Also, keep an eye out for blackfly. Spray any affected plants with diluted soapy water or remove by hand. Once pods start growing upwards from the lower part of the plant, pinch out the tips. Not only will this help reduce blackfly, it will encourage healthy pods.
Chances are, you’ve grown vegetables from seed earlier this year. By now, they’ve hopefully grown into strong plants and are ready to go out. Brassicas, French beans and runner beans can be planted out later this month, but make sure your bean supports are in place beforehand. Ensure they are planted in well, watered and mulched. As the temperature rises, they will need all the moisture they can get. If cabbage root fly is a problem on your plot, think about fitting your brassicas with collars at the base of the plant. This will prevent the flies laying eggs, which will harvest into hungry larvae.
Depending where you are in the country, pumpkins, squashes and courgettes may need to be delayed until you’ve got warmer temperatures. Otherwise, plant out into rich soil, or compost. These are hungry plants, and will need plenty of watering, and nutrients for them to help set their fruit.
In some parts of the country, the soil will be warm enough for direct sowing. As well as beetroot, peas and carrots, sow successional lettuce, spinach and radishes. As these seedlings develop, thin out accordingly, water well, and keep weed free.
With all the seedlings you have growing in the greenhouse, remember to prick out and pot on. If you don’t, they will be starved of nutrients, or grow too big for their plug/tray and die. However, there will be plants that are ready to be taken out. Some may need hardening off, but they will be ready for their final growing positions.
As space becomes available in both the greenhouse and polytunnel, think about potting up your summer greenhouse plants, such as tomatoes, cucumbers, peppers, chillies, and melons. Place these into their final greenhouse positions, and establish a regular water and feeding regime. As these plants develop, they will need staking.
With temperatures rising, consider providing shade in your greenhouse, to prevent plants being scorched. On warm days, damp down the floor to increase humidity and help prevent red spider mite. If your structure has vents, use them.
If temperatures are rising outside, they’ll also be rising inside, so consider the best place for your plants. A south-facing window may be too harsh for some plants, so consider moving them to a shadier spot.
Some plants will need extra watering and feeding to cope with the warmer conditions, and some plants will need less, so consider their needs and avoid stressing them.
If you have a tropical plant, make sure you give it a daily misting. Dust plant foliage regularly, and check for infections and pests.
Thanks to Ade Sellars from Agents of Field for kindly producing all of these tips for May.