What can I start to harvest in mid-summer?

In midsummer, all of the work you put into sowing and planting earlier in the year is coming to fruition with a host of crops reaching maturity. Early potatoes, garlic, onions, carrots and lots of salads are just some of the tasty things that will be ready, with more edibles joining their ranks before too long.

It’s easy to relax and enjoy the bounty of your garden, but don’t forget about the future. There are lots of varieties that can be sown or planted now – cauliflowers, Brussels sprouts and Swiss chard will provide pickings in the autumn, winter or even early next spring, while rocket will turn out leaves within weeks.

Sowing rocket

Rocket is a leafy salad that really lives up to its name. Sow a pinch of seeds and they will blast into life, rewarding you with plenty of piquant leaves within 21 days. It’s one of the easiest edibles you can grow, with several varieties available, from red veined ‘Dragons Tongue’ to frilly wild rocket. In the ground, choose a sunny patch and make a shallow groove with the end of a hoe or garden cane, and trickle seeds along the base, aiming to space them about 10cm (4in) apart. Cover the trench with soil and water. To raise rocket in pots, sow lightly across the surface of a 20cm (8in) pot, cover with lightly sieved compost and water.

Secure sweetcorn

A spell of windy weather can play havoc with towering sweetcorn plants, rocking them backwards and forwards so much they are in danger of toppling over. To prevent this from happening, it pays to improve their stability. No, don’t worry. I’m not going to suggest staking individually with bamboo canes. Instead, use a draw hole to pile soil up around the base of plants – a 5-7.5cm (2-3in) mound is perfect. Doing this helps to cover exposed roots at the base of the stem, improves the root system of sweetcorn plants and gives them more stability. One word of warning when using the hoe: take care not to damage roots that are near the surface.

Compact blackberries

Many owners of small gardens steer of blackberries as they consider them vigorous beasts that need loads of space. Well, traditional varieties certainly require some elbow room to thrive but over the past few years breeders have introduced varieties that are far more compact – some even have smooth stems, which means your hands won’t be cut to ribbons when picking them. Among the best are ‘Loch Maree’, ‘Loch Ness’, ‘Veronique’, ‘Coolaris Late’ and ‘Opal’. All can be planted in the ground or in 15-litre pots filled with soil-based John Innes No.2 compost. Place plants in a light, sheltered spot to ensure they’re visited by bees and other pollinators.

Harvest onions

Onions are ready for lifting when leaves turn brown and collapse. They can be eaten immediately but some varieties can be stored for months – place bulbs on wire racks to dry for three weeks, and then spread a single layer inside a box, stashing in a cool, dry, dark place. Alternatively, make a traditional onion rope. First, cut a 60cm (24in) length of twine. Gather three bulbs together and tie a knot above their necks. Wind the foliage around the twine. Add more bulbs, winding foliage upwards. When you run out of space, tie a knot around the onions at the top. Use the foliage to form a loop for hanging.

Beware whitefly

If you grow edibles in a greenhouse, keep a close eye out for whiteflies. These tiny insects suck sap, weakening growth and reducing yields. To add insult to injury, these pests also excrete a sticky substance on foliage, which provides the perfect conditions for a fungus known as sooty mould to develop. In order to check whether they are present, give plants a tap and see if any flutter out. If they do, spray plants with an organic pesticide, such as Richard Jackson’s Pest Control Concentrate. Going forward, it’s a good idea to hang some yellow sticky traps in the greenhouse – they’ll act as an early warning signal by catching pests that crash into them.