Your August fruit and veg jobs

It’s that exciting time when pumpkins start to give a glimpse of the monster crops they will become! On the other hand, pumpkins and other trailing winter squashes usually begin their mission to take over your entire plot in August. If you leave them to their own devices, their gangly stems will rapidly spread through the garden like water that’s been poured out of a bucket. Not only will the plants put on a lot of leafy growth, they will also start to form lots of small new fruits that will never have time to mature. It might seem sad to snip them off but they’ve arrived at the party too late.

Leave lots of immature fruits on the plant and it will inhibit the development of your prized large fruits that will be harvested later in autumn, before the first frosts. Cut back any stems that have tiny fruits at the tips, cutting back to just above a healthy leaf. If you have five or more fruits developing on the plant, lots of healthy foliage is still needed to ensure a heavy crop, so train long stems into their allotted space if they are encroaching on other crops, by winding them in a circle and securing the stems to the ground with wire pegs.

Cut off leaves that are acting like umbrellas and shading fruits from the sun, because the sun exposure helps to harden the skins and give you that jumbo ‘indestructible’ harvest at the end of autumn. Also remove any growth that is greying (showing signs of mildew) or crispy, to allow the maximum amount of moisture to get down to the plant’s roots when it rains or when you water.

• How to grow pumpkins and squash

Harvesting beetroot

When to pick the sweet and succulent roots of beetroot is a matter of preference, depending on whether you want something small and delicate for a salad, or a more heavyweight vegetable for cooking. When I was a child, there always seemed to be a steaming saucepan on the hob in the kitchen in the summer holidays, full of giant beets the size of coconuts that seemingly took forever to cook. Eventually they would end up in rather curious beetroot sandwiches. Despite this bizarre serving suggestion, I couldn’t argue with the sweet flavour of the soft roots when they were eventually ready.

Rather than harvest in succession along a row or patch, remove every other root to give the ones left behind space to grow into and access moisture. You should be able to just pull up the roots but if the ground is very hard, thoroughly soak it the day before harvesting to make it easier and also help future roots to swell without going dry and woody.

Beetroot foliage is edible but by now it’s getting to that ‘it’s edible but not a pleasant experience’ stage where top growth is tough and much better added to the compost heap. Beetroot won’t keep that well after harvesting in summer so is best used immediately after picking. Autumn roots will keep for longer in a cool, dry place indoors if you twist off the foliage with your hands.

• How to grow beetroot

Lifting carrots

Harvesting carrots is one of those wondrous gardening moments, with the rows of feathery, rather ordinary foliage revealing their tantalisingly bright secrets below ground. And eating a full-flavoured homegrown carrot for the first time is like discovering a new vegetable.

It can sometimes feels like playing ‘lucky dip’, if soil is bad though. All can look lush and leafy on the top but there is no telling what you will find beneath. ‘Thin’ free draining soils free of stones will give the most impressive roots. Sadly I have none of these qualities in my garden soil, with container-growing a much more bountiful option, also giving very clean roots.

Push a digging fork into the soil, near but not too close to the foliage of your carrots, and push it down deep before levering up the crop. Hold the foliage while you loosen the soil and gently lift the plants. The crop is ready to harvest any time from ten weeks after sowing, depending on the size that you want the carrots to be. Harvest from one end of the row to the other to reduce the risk of carrot fly laying eggs around disturbed roots.

This is more of a problem in the second half of August, when the female flies of the second generation of this pest are looking for places to lay eggs. Firm the soil well, where you have been harvesting, and water the rest of the row well. Carrots are best lifted as and when you want them at this time of year, for maximum freshness and flavour.

• 10 ways to avoid carrot fly

Tidy strawberries

What a fickle lot gardeners can be! In those heady, mid-summer strawberry picking days, perhaps no other plant gets as much attention when there are such delicious pickings to be had. Then, once the final strawberry of the summer is picked, it’s easy to forget that the plants ever existed and not even acknowledge their presence until the next year. Some simple maintenance now will help improve next year’s crop though.

A bit of foresight and forward planning is always one of the strongest weapons of a grow-your-own gardener. Remove netting and mulches from the plant so that you can easily remove all the old plant material, which can lead to disease if left around the base of the plants. Once this has been removed it will expose any weeds that had managed to hide themselves. Get rid of these, then once the crop is weed and debris-free, cut all the old growth back to just leave 10cm of stem. This will leave you with a clear view of all the young leaves and new runners.

Position new runners in gaps in the row and peg them down with a bent piece of wire. Unwanted runners can just be snipped off with secateurs, cutting right back to their source. If you want to raise some new pot plants to plant out elsewhere, dig a small planting hole near the runner with a trowel and place a 5cm (2in) pot of peat-free multi-purpose compost into the hole, then peg the runner down over the compost, again with wire, and water well.

When the runner has rooted in a few week’s time, it can be cut off the main plant and hey presto, you have a new strawberry plant in a pot for planting somewhere else. Don’t forget to keep watering pegged down runners in dry spells for the rest of the month.

• How to propagate strawberries from runners

Feed and harvest cucumbers

I just can’t grow enough cucumbers in my household, with kids at home who devour the mouth-watering fruits like they are ice lollies. Maybe you’ve got so many that you can’t possibly eat them all! Leaving them outside in a cardboard box for passers-by seems a popular trick in my neighbourhood and sharing your gluts can be a good way of getting to know the neighbours. Keep feeding and watering and the family feeding/community service can continue for several weeks yet.

Cucumbers need low levels of nitrogen but a high level of potassium, for fruits to develop well. A liquid tomato food is good or a homemade comfrey fertiliser will also do a good job. I always put a small dribble of plant food in my watering can each time that I water, to get into the habit of regular feeding but if in doubt when using an off-the-shelf plant food, just follow the maker’s application rates.

Keep harvesting the fruits when they have developed a good colour on all sides and simply snip off the stalk at the top of the fruit. I prefer to snip rather than pull most crops (especially when fruits are heavy) because it reduces the chances of breaking stems or unsettling the roots of the plant.

Cucumbers will keep in the fridge for at least a week, but I can’t resist the taste of the warm juicy flesh straight from the plant. And neither can my family!

• How to grow cucumbers

Check sweetcorn for ripeness

Sweetcorn always feels like a precious crop, perhaps because each plant that has been coaxed through spring and summer to become a towering giant only gives a rather sparing harvest of one or maybe two cobs. Try to have a look at the plants every day this month, and when you notice that the silky tassels on the cob have turned brown, start to unfold the sheath surrounding the cob, to test for ripeness.

Press a kernel with your fingernail and if milky sap comes out, it’s ripe. If it’s still watery, fold the sheath back over and have another look a week later. If the sap is thick and doughy, the cob is past its best. Immediately check the other cobs if this is the case, so hopefully some cobs can be salvaged before they are spoiled.

Sweetcorn cobs are best cooked immediately after harvesting for maximum flavour, although ‘supersweet’ varieties such as ‘Conqueror’ or ‘Ovation’ will keep their flavour for a week or so after harvesting. If you have a surplus, the cobs can be frozen right after picking to retain their flavour until cooked. Boil the cobs immediately for three to four minutes, then plunge them into ice cold water for four to five minutes. Remove from the water, pat the cobs dry, and place on a baking sheet in the freezer for an hour or two until frozen. Then wrap with cling film, place it inside a freezer bag and put it back in the freezer where it will keep for up to six months.

• How to grow sweetcorn

Check brassicas for pests

Having a healthy crop of winter brassicas to harvest can also mean a healthy winter is ahead. Winter brassicas are full of goodness. Whether it’s the high levels of vitamin C, K and iron in kale, or the folate and fibre in Brussels sprouts, a healthy brassica bed for winter pickings will reinforce the truth that gardening is good for you.

For all their health benefits to the grower, brassicas can have ailments of their own and now is a good time to give them a summer health check. Pigeons will keep pecking at brassica leaves, especially young ones if plants aren’t netted. Raise up the net on poles or by stacking up bricks if the plants are getting squashed by the netting.

Adult cabbage white butterflies will still be laying eggs this month and next. There are two types, the large white caterpillars, which are yellow and black, and the smaller small whites, which are pale green. Both are very destructive, but a nightly inspection to pick them off will prevent any damage being done.

You may also see whitefly on your brassicas, but they are unlikely to do any damage to edible parts of your crops, with the exception of kale –where the pale green little nymphs will congregate on the tasty shoots that you want to harvest. Try blasting them off with a jet of water then wiping off any stragglers with a clean cloth.

Tie in new raspberry canes

If any incentive were needed for this task it should be the sweet taste of the delicious fruits that have just been savoured, whether it was in a pavlova, a fruit salad or if the fruits never even made it indoors!

Attention now turns to the fresh new canes that have yet to produce fruit, which need tying in. Securing them to a support will prevent them from being knocked around by strong winds and will also make it easier to feed and water the crop in future because there will be exposed soil closer to the base of the plant, allowing you to apply water and fertiliser much closer to the plant’s roots, to help them take in goodness.

It’s easy to tell the old, pale, woody canes apart from the soft, fresh green new ones and if any old fruited canes are left, cut these off at the base. Then select the strongest new canes for tying in, aiming for one plant every 8cm along the row and tying them to horizontal wires using soft string. Cut off the rest of the new growth at ground level to ease ‘congestion’. This will allow the remaining canes to crop to their full potential when they bear a harvest next summer.

• How to grow raspberries

Keep watering maincrop potatoes

Maincrop potatoes are one of the most substantial crops that you can grow, capable of providing the backbone of plenty of winter meals. Although potatoes are reasonably drought tolerant, they need regular watering in hot, dry spells if foliage is still green, in order to give as good a crop as possible.

Harvesting can begin towards the end of the month if foliage has died down but it's best to leave the potatoes under the soil for a couple of weeks to help the skins of the tubers harden. This will increase their storage potential. Give potatoes still in good leaf a thorough soaking until puddles form around the plants if conditions are hot and dry.

If you have maincrop potatoes in pots, move them into shade during very hot days to prevent the foliage from wilting and potentially dying back early, and water them well each time the compost is dry. Reach into the container and push your finger into the compost to test for watering. If it is dusty and dry, give the plant a thorough soak.

• How to grow potatoes