August is the month of abundance and beginnings at once: the garden is handing you its biggest harvests — potatoes, onions, garlic, tomatoes, beans — while the empty beds left behind are your chance to sow the green manures and autumn crops that set up next year. It is the busiest harvest month, and the most forward-looking.
Here is exactly what to do this August in Central and Western Europe, in priority order. Published in late October so you can plan ahead — read it now, and arrive in August knowing precisely what to do instead of guessing. This is the eleventh of our twelve monthly checklists — one more to go, and the full year will be covered.
| Job | Why now | How |
|---|---|---|
| Harvest maincrop potatoes | Tops dying back; tubers at full size | Lift on a dry day; dry before storing |
| Lift and dry onions & garlic | Foliage flopping; bulbs ready | Lift carefully, then dry in sun or under cover |
| Sow green manures | Empty beds need covering now | Scatter crimson clover or phacelia seed |
| Order autumn planting stock | Best choice before sell-outs | Garlic bulbs, onion sets, broad bean seed |
| Keep watering | Heat continues; crops still swelling | Deep soak, mulch, water in the morning |
| Clear spent crops | Frees space for autumn sowings | Compost healthy foliage; bin anything diseased |
| Save seeds | Ripe now; dry weather for drying | Tomatoes, beans, lettuce — see our seed guide |
Step 1: Harvest maincrop potatoes — lift on a dry day
When the potato tops yellow and die back, the tubers are ready: choose a dry day and fork them up carefully, working from the edge of the row inward so you do not spear the crop. Leave the tubers on the soil surface for an hour or two to dry — the skins firm up and store far better.
Sort as you go: perfect tubers for storing, damaged ones for eating first (a nicked potato rots in store and spoils its neighbours). Store in hessian sacks or paper bags in a cool, dark, frost-free place, and check monthly through winter — one rotting tuber spreads fast. See our blight guide for what to do with any blighted foliage: bin it, never compost it.
Step 2: Lift and dry onions and garlic properly
Onions are ready when most of the foliage has flopped over; garlic when the lower leaves brown and only a few green ones remain. Ease them up with a fork on a dry day — do not pull hard, or you tear the necks and invite rot.
Drying is the step that decides storage life: lay the bulbs in a single layer in the sun for a week, moving them under cover if rain threatens, until the skins are papery and the necks are completely dry and tight. A greenhouse bench, cold frame or airy shed works just as well. Only store fully dry bulbs — damp necks rot in store. Well-dried onions keep into winter; garlic keeps for months.
Step 3: Sow green manures on every empty bed
August is prime green-manure sowing time: as beds empty of potatoes, onions and early crops, rake them level and sow immediately. Crimson clover and phacelia sown now establish fast in the warm soil and cover the ground before autumn weeds arrive.
This is one of the highest-value jobs of the year for almost zero effort: a packet of seed scattered in August becomes free fertility, weed suppression and soil protection all winter. Beds you will plant with garlic or broad beans in autumn skip the green manure — they are the crop. Every other empty bed gets one.
Step 4: Order autumn planting stock while choice is best
August is ordering month for the autumn plantings: garlic bulbs, autumn onion sets, and broad bean seed for overwintering all sell out of the best varieties by September. Order now and they arrive in time for October and November planting.
While you are at it, order spring bulbs for the flower borders and any seed you still need for late sowings. The gardeners with the best autumn plantings are the ones who ordered in August — everyone else makes do with what is left. Keep a simple list of what you plant where; next year's rotation planning (see our first vegetable garden guide) depends on it.
Step 5: Keep watering — August heat is relentless
It is tempting to ease off in August, but crops are still swelling: tomatoes ripening, beans flowering, salads bolting at the first drought. Water deeply in the cool of the morning, soil only, never foliage — our watering guide covers the technique.
Check the mulch and top it up where it has thinned — August sun bakes bare soil hard and every unmulched bed loses moisture fast. Pots and containers need daily watering, sometimes twice in a heatwave. A week of neglect in August undoes months of good growing.
Step 6: Clear spent crops and feed the soil
August is when the first summer crops finish: bolted salads, exhausted early peas, finished broad beans. Pull them promptly — every square metre of spent crop is a square metre not growing a green manure or an autumn sowing. Compost the healthy foliage (see our compost guide); bin anything diseased, especially blighted potato or tomato foliage.
This is also the moment to save seeds from your best plants: tomatoes at their ripest, beans drying in their pods, lettuce flowering. August's dry weather is ideal for drying seed — collect on a dry afternoon and get it under cover the same day.
Troubleshooting: August problems
Blight appearing after August rain: Warm, wet spells trigger it fast — check potato and tomato lower leaves weekly. At the first sign, cut and bin affected foliage immediately — see our blight guide. There is no cure, only speed.
Onions rotting instead of drying: Lifted too late or dried in damp conditions — necks must dry fully. Next year lift a week earlier, and dry under cover with good airflow rather than gambling on sunshine.
Beans dropping flowers in heat: The classic August bean complaint — heat and drought stress. Water deeply, mulch thickly, and mist plants in the evening to raise humidity around the flowers.
Nothing left to sow — beds sitting empty: Sow green manures now (Step 3), or quick catch crops: radishes, spinach and spring onions sown in August still crop before winter.
What to do this October
Reading this in late October? August is past — but its lessons set up your October. The beds you should have sown with green manure in August can still be sown now with hardy types (winter rye, field beans — see our green manure guide). Stored potatoes and onions need their monthly check: remove any softening ones before rot spreads.
And order next August's seed potatoes and garlic now if you have not already — the October routine (see the full October checklist) is where next year's August harvest really begins.
Frequently asked questions
Is it too late to sow anything in August?
No — green manures, spinach, radishes, spring onions and oriental leaves all sow well in August. It is too late for slow crops, but perfect for fast catch crops and soil feeders.
When do I stop watering onions?
Once the foliage starts flopping — usually late July or August. Stop watering entirely, let them ripen in dry soil for a week or two, then lift. Watering late gives thick necks that will not store.
How do I store maincrop potatoes?
Dry them on the soil for a few hours after lifting, then store in the dark (light turns them green), cool and frost-free, in breathable sacks. Check monthly and remove any going soft.
Can I plant garlic in August?
Too early — wait until October or November. Garlic needs the cold of winter to form proper bulbs; August-planted cloves just sit and risk rotting. Order the bulbs now, plant them later.
Related guides
- July Garden Checklist: What to Do Now (Europe) — last month's harvest season
- Green Manures: Feed Your Soil for Free — this month's highest-value sowing
- How to Grow Potatoes at Home: Beginner's Guide — the maincrop harvest in detail
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