Garden writer Aaron Bertelsen and head gardener Benjamin Pope explain the tasks you ideally should be doing in the garden this month. Don't miss our gardens to visit in August, and enjoy our piece on the best flowers in August.
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Gardening jobs for August in the flower and kitchen garden
By Aaron Bertelsen
If you must go away, plan ahead. You are going to need help in the garden. And don’t forget, it’s not just about watering. Harvesting is equally important to keep plants productive and avoid food going to waste. Much better to have someone else enjoy it if you can’t eat it yourself.
Leafy crops such as Swiss chard and kale will benefit from a thorough clean-up. Weed around them, and get rid of any yellowing or damaged leaves. This will help ensure good air circulation, making the crops less vulnerable to white fly and moulds. It also enables water to get closer to the stem and the roots, rather than being trapped and then running off the leaves into the surrounding soil.
Early apples will be starting to ripen now. Gently turn the fruit in your hand, and if the stem comes away from the branch, the apple is ready to harvest.
If you have not taken my advice and are growing tomatoes other than the reliably blight-resistant ‘Crimson Crush’, this is a good time to spray. Look for an organic copper spray, or one containing baking soda (or of course make your own).
Lift any remaining maincrop potatoes. Choose a warm, sunny day and leave the potatoes on top of the soil to give the skins a chance to dry out fully before you store them. This way they will be much less likely to rot.
Sow fennel under glass. I find that sown now, fennel is much less likely to dry out and is not nearly so prone to bolting.
Keep sowing salad crops. A sowing every three or four weeks at this stage will see you into the early winter. You can thank me then.
I like to do a late sowing of beetroot at around this time. There is still time for the roots to develop, and the leaves make a delicious – and colourful – addition to autumn and winter salads.
This is also a great time to sow onion seed. It took me a while to find an onion that would do well in heavy clay soil, but now I have the answer: Allium cepa ‘White Lisbon’. I like to sow quite thickly, so that I can add the thinnings to my salads.
There is still time to get summer and winter radishes into the ground too. They are quick growing and an excellent choice for shadier areas of the garden.
Getting tomatoes to ripen can sometimes feel like a race against time. Maximise the amount of sunlight that reaches the fruit – and reduce the risk of blight, which can be spread by soil splashing up on to the plants when you water – by stripping the lower leaves from your plants and pinching out the diagonal shoots that often appear between the main stem and the branches. Once my plants are around 1.5m tall I like to pinch out the tops too, to encourage them to put their energy into fruiting.
Now is a good time to give your perennial herbs a good cut back and clean up so that they have the time to recover before the cold months. Take out any old and damaged wood, cut back to where you can see new growth and remove any weeds. Then water well with a liquid feed such as seaweed.
By Benjamin Pope
Cut back lavender Now is the perfect time to cut back lavender, removing most of the new growth if you want to keep plants compact and healthy. Any lavender flowers can be dried then used for arrangements, cooking or fragrant oils.
Maintain water features Clean ponds and water features now to avoid disturbing wildlife during the critical winter months of hibernation or reproductive months of spring and early summer. Remove
excessive pond sludge and weed growth and if needed treat with organic algaecides to control algae or blanket weed.
Propagate tender perennials Take semiripe cuttings of tender perennials including Helichrysum petiolare and Pelargonium tomentosum. The rooted cuttings will take up less indoor space in winter, providing you with young vigorous plants next year.
Plant bearded iris Summer is a good time to lift and divide bearded iris and order bareroot stock of any new cultivars. Trim leaves and remove sections of old rhizomes before replanting.
Order bulbs Plan your spring-flowering bulbs now and start ordering from online nurseries to ensure you get the cultivars you want and that they are delivered fresh, directly to your door for autumn planting.
Don't miss our guide to what to sow and plant in August.
