Grow Your Own · 10–16 August

The garden turns towards autumn

This week is about ripening what is already growing, clearing finished crops and creating new plants for very little cost.

Photo: Amie Roussel via Unsplash

There is a subtle change in the garden during the second week of August. Summer is still very much here, but the days are gradually becoming shorter and thoughts begin to turn towards autumn.

Some plants need a little encouragement to finish ripening their crops. Elsewhere, onions are ready to be lifted, raspberry canes need pruning and strawberry runners can be turned into free plants for next year.

Empty ground doesn’t need to remain bare. It can be replanted with hardy leaves or sown with green manure to protect and improve the soil.

Remember: northern growing conditions can be a week or two behind warmer areas of the UK. Let your plants and the weather guide you. Never lift or prune a crop simply because the calendar says it might be ready.

Sow now for the colder months

This week’s sowings are less about quick summer salads and more about crops that tolerate cooler, shorter days.

Corn salad

Sow in a short outdoor row or a container. It is hardy, mild in flavour and useful when ordinary lettuce becomes harder to grow.

Winter purslane

Also called miner’s lettuce, this produces tender leaves during cooler weather. Sow outside or under cover for a later crop.

Land cress

Land cress has a peppery flavour similar to watercress but grows in ordinary soil. Keep it watered during dry weather.

Winter radish

Sow varieties such as black Spanish or mooli. These take longer to grow than small summer radishes and produce much larger roots.

Chervil

Sow in a container or partially shaded bed. Cooler conditions suit it better than the heat of early summer.

Parsley

Sow in pots now for young plants that can be moved under cover and used during autumn and winter.

Container idea: sow a pot containing corn salad, winter purslane and land cress. Keep it near the house so you can easily pick a few leaves during colder weather.

Give empty beds a job

Beds cleared of early potatoes, peas or broad beans don’t have to remain empty. If you don’t need the space for autumn vegetables, consider sowing green manure.

Green manure is a crop grown to cover and improve the ground rather than to eat. It can help suppress weeds, protect the soil from heavy rain and add organic matter when it is cut down.

Good choices for August

Phacelia: quick-growing and popular with pollinating insects if allowed to flower.
Buckwheat: useful for quickly covering bare ground, although it won’t tolerate hard frost.
Crimson clover: a longer-term choice that can help improve the soil.

Check the packet to make sure your chosen green manure fits with your crop rotation. Mustard, for example, belongs to the brassica family and may not suit a bed where cabbages or broccoli will grow next.

If you don’t want to sow green manure, cover the cleared bed with cardboard topped with compost or well-rotted manure.

🍅 Help outdoor tomatoes finish their crop

By the middle of August, newly formed outdoor tomatoes may not have enough time to grow and ripen before colder weather arrives.

Stopping cordon tomatoes

If an outdoor cordon tomato has produced four or five good trusses of fruit, remove the main growing tip. Cut just above two healthy leaves beyond the highest fruit truss.

Continue removing new side shoots. This directs more of the plant’s energy into ripening the tomatoes already present.

Don’t do this to every tomato

Bush tomatoes should generally be left to grow naturally. Greenhouse tomatoes have a longer protected season, so their growing tips can usually be left until later.

Remove only badly yellowed or diseased leaves. Taking away too many healthy leaves reduces the plant’s ability to make energy.

Harvest and store

Lift onions, shallots and garlic

Onions and shallots may be ready when their foliage naturally yellows and folds over. Don’t bend healthy leaves down by hand.

Choose a dry day and gently loosen the bulbs with a fork. Spread them somewhere warm, dry and well ventilated to finish drying.

If rain is forecast, move them into a greenhouse, shed or covered area with plenty of airflow. Avoid piling damp bulbs together.

Store only firm, undamaged bulbs. Use damaged or thick-necked onions first because they are less likely to keep well.

Photo: Sandie Clarke via Unsplash

Prune summer-fruiting raspberries

Once summer raspberries have finished producing fruit, the old canes can be removed. These canes will not fruit again.

Identify the older brown canes that carried this year’s fruit.
Cut those old canes down at ground level.
Leave the fresh green canes because they will carry next summer’s crop.
Select the strongest new canes and tie them loosely to their support.
Remove weak, damaged or badly positioned growth.

Be careful: don’t prune autumn-fruiting raspberries now. They are beginning to carry this year’s fruit and are normally cut down during winter.

Make free strawberry plants

Strawberry plants often produce long stems called runners. Small plantlets form along these stems and can be rooted to create new plants for next year.

Choose a healthy runner from a productive plant.
Fill a small pot with compost.
Place the pot beside the parent strawberry plant.
Press the first strong plantlet onto the compost and hold it in place with a bent piece of wire or a small stone.
Leave the runner attached to the parent while roots develop.
Once the new plant is firmly rooted, cut the connecting runner.

You can use the new plant to replace an older strawberry plant or share it with somebody else.

What may be ready this week

Second-early potatoes: lift them carefully and allow the skins to dry before storing any undamaged tubers.
Sweetcorn: check when the tassels have turned brown. A ripe kernel should release a milky liquid when pressed.
Onions and shallots: lift them once their foliage has naturally yellowed and fallen.
Plums: ripe fruit should come away with a gentle twist rather than needing to be pulled.
Blackberries: pick fully black, plump berries that come away easily.
Summer raspberries: collect the final fruits before pruning the old canes.
Beetroot: lift roots before they become oversized and woody.
Carrots: harvest as needed and cover the remaining crop with fine mesh if carrot fly is a problem.

Other jobs around the plot

Remove finished pea and broad bean plants, leaving the roots in the ground to break down.
Store clean, dry plant supports once crops have finished with them.
Add healthy plant material to the compost heap, cutting thick stems into smaller pieces first.
Turn the compost heap and add dry cardboard if it has become wet or unpleasantly slimy.
Net ripening blackberries, plums and other fruit if birds are taking more than their share.
Remove any fallen or damaged fruit from beneath trees.
Support heavily laden apple and plum branches before they snap.
Make a note of empty spaces that can be used for autumn planting.
Keep greenhouse doors and vents open during hot weather, closing them later if nights become unusually cold.

Growing with children

Collect seeds for next year

Look for dry seed heads on flowers such as marigolds, calendula, poppies or sunflowers. Children can shake the seeds onto a sheet of paper and help remove pieces of dried plant material.

Place the seeds in a paper envelope and ask children to decorate it. Remember to add the plant’s name and the year.

Leave the seeds somewhere dry before sealing the envelope. Avoid collecting seeds from poisonous plants and supervise children closely, as seeds should never be eaten unless they are known to be edible.

This week’s quick checklist

Stop mature outdoor cordon tomatoes
Lift onions when their tops naturally fall
Dry onions and garlic before storage
Prune old summer raspberry canes
Root one or two strawberry runners
Sow a container of hardy winter leaves
Sow green manure on an empty bed
Check sweetcorn for ripeness
Clear finished peas and broad beans
Collect dry flower seeds with children