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What to Do in the Garden This Week - August 21st

Published on August 21st 2020

by AlanGardenMaster. All rights reserved

Echinacea daisies and sea holly in a garden
This week, I've some tips on plant care if you're lucky enough to be away, some propagation ideas and some planning ahead for winter planting, including priority planting of some great bulbs. But make sure whatever you get up to in the garden, enjoy it!
For more information check out my full monthly guides:
A close up of Dahlia flowers

What to Do In the Garden This August


A pile of orange tomatoes

What to Do in the Vegetable Garden This August


Watering and holidays

house or indoor plants
  • Indoor plants will survive your absence if they have enough water. Putting them in the bath on top of an old wetted towel may also be enough. Placing them on a draining board covered by capillary matting -with the ends in a partially filled sink- works well too.
  • It may seem obvious, but this is the time of the year that saucers under pots help to stop plants drying out by increasing the water holding capacity.
  • Ask a neighbour, friend or relative to water your plants for you while you're away. Encourage them to take vegetables and fruits that otherwise would go to waste.
  • Moving plants to the shady side of your home will help reduce water demand.
A Hosta plant in a pot


  • Fill spaces in the veg patch with crops that will provide tasty veg in winter. Sow American land cress, corn salad (Lamb’s lettuce), rocket, and radicchio. These are not hard to grow and will provide tasty, nutritious homegrown salads long into the colder months!
  • August is the last month when it's safe to prune stone fruit trees - trees with fruits containing stones rather than pips. Plums, cherries, apricots, peaches and nectarines are best pruned during the summer when they are less likely to get infected with the incurable Silver leaf disease.
Silver leaf disease on plum shoots
  • Sow seeds of autumn onion (sometimes called Japanese onion) this month to give you the earliest crop of next year. You’ll be able to buy onion sets of these next month, but seeds are cheaper!
Onion seedlings in a garden
  • Regularly pick runner beans, French beans and courgettes. If you don’t, they will stop producing. These can be used to make excellent chutney or can you can give them to neighbours and friends.
  • Harvest all marrows and cucumbers regularly. If you don’t, they will also stop producing. Give excess away or conserve them. It's even better to throw excess on the compost heap rather than leave them on the plants!
  • Remove lower leaves if they show signs of powdery mildew. Try spraying with a mix of 50:50 milk and water. Let me know if it works for you too!
Powdery mildew on marrows
  • Make sure to provide tomatoes, sweet peppers, melons, chillies and aubergines with high potash liquid feed.
  • Remove lower leaves from tomato plants when they start to show signs of going yellow. Removing them too soon can lead to uneven fruit ripening.
  • Keep watering tomatoes evenly. If it varies too much, your fruits may get dead black tissue at the bottom end called ‘blossom end rot’.
Red tomatoes sitting on a table

Flowers and ornamental plants

  • Trim lavender as the colour fades from the flowers. Remove just a little bit of the shoot too, as this will encourage branching out. If plants have become straggly, delay harder pruning until late spring.
  • If you want to dry lavender, then you need to harvest the flowers before the colour fades. Hang them upside down in a cool, dry and airy place.
Harvesting lavender at Babylonstoren
  • You can take semi-ripe cuttings of many plants now. These are cuttings that have a slightly hardened and woody lower end and will root best on a mist bench. It's surprising what will root in a pot of compost covered with a thin polythene bag.
  • Get catalogues as they become available and order ornamental trees for winter planting. These will normally be delivered in mid-winter.
  • Plant snowdrop bulbs and anemone corms just as soon as you can. They can be challenging to get going, but by planting early, they can establish much more readily. The longer they are out of the ground, the more dormant they become and challenging to re-awaken.
  • Autumn flowering crocus should be planted as soon as possible as they will flower this October. They bloom before the leaves appear and this has earned them the common name ‘naked ladies’.
pink autumn crocus flowers
  • Hyacinths prepared for forced flowering around Christmas will be coming out of temperature treatment now. Get potting them up for some inexpensive scented decorations for Christmas!
  • Plant Nerine bulbs in a position where they get plenty of sun and where the soil dries quickly. By a wall or hedge works well.
pink Nerine flowers against a wall

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