What to Sow in Late Summer for an Autumn Harvest
Late summer offers an important second sowing season. As early crops are harvested, their spaces can be replanted with fast-growing vegetables, salads and hardy crops for harvesting during autumn and, in some climates, throughout winter.
Success depends on choosing suitable crops and varieties, sowing while there is still enough warmth for germination and allowing for slower growth as daylight declines.
Rather than following a fixed date, work backwards from the expected first frost and consider the protection available. The Sowing Calendar in Your Growing Companion can help identify crops suited to the location and time of year.
Why Sow in Late Summer?
Spring is often treated as the main sowing season, but some vegetables perform better when started later.
Late-summer sowing can provide:
Fresh vegetables after summer crops have finished
A continuous supply of salad leaves
Tender young roots for autumn harvesting
Hardy crops that stand through colder weather
Overwintering plants for an early spring harvest
Better use of beds that would otherwise remain empty
Cooling temperatures can also reduce the stress experienced by crops such as spinach, rocket and coriander, which may bolt quickly during hot weather.
Pest pressure may decline later in the season, although young plants will still need protection from slugs, snails, flea beetles and other locally active pests.
Begin with the First-Frost Date
The first expected frost is one of the most useful dates when planning late sowings.
Count the approximate number of weeks between the intended sowing date and the first frost. Compare this with the days to maturity stated on the seed packet, but do not treat that figure as a guarantee.
Days to maturity are usually based on favourable growing conditions. As autumn approaches:
Days become shorter
Temperatures fall
Soil remains wet for longer
Growth gradually slows
Crops take longer to reach maturity
Allow extra time whenever possible. A crop described as maturing in 40 days may take considerably longer when sown near the end of summer.
Frost is not the only limit. Even in frost-free conditions, growth may slow greatly once daylight drops below the level required for active development. The aim is to establish crops while warmth and useful daylight remain.
Fast-Growing Salad Leaves
Salad leaves are among the most dependable late-summer crops because they can be harvested young.
Suitable choices may include:
Loose-leaf lettuce
Rocket
Mizuna
Mustard greens
Pak choi
Tatsoi
Komatsuna
Spinach
Lamb’s lettuce
Winter purslane
Baby chard
-- Beet leaves
Choose varieties recommended for autumn, winter or low-light growing where available.
Leaves can be harvested individually using a cut-and-come-again method, allowing the centre of the plant to continue producing. Alternatively, sow closely for baby leaves and cut the whole row while young.
Small sowings made at intervals are usually more useful than one large sowing. They reduce the risk of producing more leaves than can be used at once and provide replacements if an early batch fails.
Radishes and Other Quick Roots
Radishes are particularly useful for filling short gaps because some varieties can be ready within a few weeks.
Sow them thinly in moist soil and avoid overcrowding. Restricted roots, dry conditions and excessive heat can lead to small, woody or strongly flavoured radishes.
Other roots that may be suitable include:
Turnips
Baby beetroot
Fast-growing carrots
Kohlrabi
Oriental radishes
The likely result will depend on sowing time and climate. Crops sown later may produce tender baby roots rather than reaching full size.
Carrots need enough time to establish before cold weather and are best suited to earlier late-summer sowings or milder climates. Select a quick-maturing variety and keep the seedbed consistently moist during germination.
Spinach
Spinach often performs better as temperatures fall. Summer heat can cause it to bolt, while late-summer sowings may provide leaves through autumn and possibly into winter.
Sow spinach in moist, fertile soil and protect seedlings from slugs and snails. Thin plants if they become crowded and begin harvesting outer leaves once they are large enough.
Hardy varieties can survive considerable cold, especially under fleece, cloches or an unheated greenhouse. In very cold regions, establish plants early enough to develop several healthy leaves before severe weather arrives.
Rocket and Coriander
Rocket and coriander frequently bolt when grown through hot weather. Sowing them as temperatures begin to moderate can produce steadier growth and better-quality leaves.
Both crops need moisture during establishment. If late summer remains hot, sow them in a position receiving some afternoon shade or use temporary shade until seedlings emerge.
Rocket can be harvested as baby leaves, while coriander can be cut lightly and repeatedly. Later sowings may remain productive for longer because the plants are under less heat stress.
Oriental and Asian Greens
Many Oriental and Asian greens grow rapidly and tolerate cooler conditions. They can can provide leaves, stems or compact heads during autumn.
Possible choices include:
Pak choi
Tatsoi
Mizuna
Mibuna
Komatsuna
Mustard greens
Chinese cabbage
These crops can struggle when sown during the hottest part of summer, so timing is important. Sow once temperatures begin to ease, or start them in modules somewhere cooler before transplanting.
Flea beetles and caterpillars may still damage young plants. Fine insect mesh can provide protection, provided the crop was pest-free when covered.
Some varieties are more cold-tolerant than others. Check the seed description and choose one intended for the season.
Turnips and Kohlrabi
Turnips and kohlrabi can mature relatively quickly when moisture and fertility are adequate.
Turnips may be grown for their roots, leaves or both. Harvest young roots before they become coarse. Kohlrabi should also be harvested while the swollen stem is tender rather than waiting for the largest possible size.
Both belong to the brassica family, so consider crop rotation and any history of clubroot or other soil-borne brassica problems before choosing their location.
Spring Onions
Late-summer sowings of spring onions may provide small stems during autumn in mild conditions. Hardy varieties can also overwinter and resume growth in spring.
Sow thinly in shallow drills or modules. Keep the soil moist during germination and prevent weeds from competing with the slender seedlings.
Growth will slow as temperatures and daylight levels fall. If the plants do not reach harvestable size before winter, leave them in place where conditions permit and harvest them when growth resumes.
Pea Shoots
Peas sown for shoots offer a quick crop without needing enough time to produce mature pods.
Sow peas more closely than plants intended for pod production. Once the shoots are approximately 10–15 centimetres tall, cut the tender growing tips above the lowest leaves. The plants may produce further shoots for another harvest.
Pea shoots can be grown outdoors, under cover or in containers. They are useful when the remaining season is too short for a full pea crop.
Chard and Kale
Chard and kale need more time than the quickest salad crops, but early late-summer sowings may establish well enough to provide young leaves during autumn.
In colder climates, their main value may come later. Strong plants can remain in the ground, survive winter with suitable protection and resume growth when conditions improve.
Choose compact or baby-leaf varieties when sowing later. Full-sized plants require more time, space and fertility.
Sowing During Hot, Dry Weather
Although autumn is approaching, late-summer soil may still be hot and dry. These conditions can prevent successful germination.
To improve results:
Water the seedbed before sowing
Sow during a cooler part of the day
Use temporary shade where necessary
Cover seeds with the recommended depth of soil or compost
Keep the surface consistently moist
Avoid washing small seeds out of shallow drills
Check containers and modules frequently
Remove shade once seedlings are established
A board, sheet of cardboard or piece of damp fabric can sometimes be placed over a freshly sown row to conserve moisture. It must be checked daily and removed as soon as germination begins.
Spinach and lettuce seeds can germinate poorly when soil temperatures are too high. If conditions remain extremely hot, sow in modules in a cooler place and transplant later.
Direct Sowing or Modules?
Both methods can work, but each has advantages.
Direct sowing is useful for:
Radishes
Carrots
Turnips
Rocket
Spinach
Salad-leaf mixtures
Green manures
Sowing in modules is useful for:
Lettuce
Pak choi
Tatsoi
Mustard greens
Chard
Kale
Kohlrabi
Spring onions
Modules allow seedlings to begin growing while the previous crop still occupies the bed. They also make it easier to protect young plants and control moisture during germination.
Do not leave seedlings in small modules for too long. Restricted roots and nutrient shortages can delay establishment after transplanting.
Prepare the Ground Lightly
After removing the previous crop, clear weeds and inspect the soil.
If the ground remains loose, moist and in good condition, extensive cultivation is unnecessary. Apply a thin layer of mature compost where the next crop is likely to benefit and disturb the soil only enough to create a suitable surface for sowing.
Very fine seeds need close contact with the soil. Break up large lumps in the sowing row and remove anything that would obstruct germination.
Avoid applying strong fertilisers immediately before sowing root crops. Excessive nitrogen can encourage leafy growth at the expense of roots.
Watering Late-Summer Sowings
Newly sown seeds need steady moisture. Repeated cycles of drying and soaking can result in poor or uneven germination.
Water gently and regularly until seedlings are established. As temperatures fall, reduce watering according according to the weather and the moisture already present in the soil.
Older crops may cope with occasional surface dryness, but small seedlings have shallow roots and remain vulnerable. Mulch between established plants once they are large enough, keeping heavy material away from delicate stems.
Protect Young Crops
Late-sown vegetables may face pests as well as changing weather.
Depending on local conditions, protection may be needed from:
Slugs and snails
Flea beetles
Caterpillars
Birds
Rabbits and other animals
Strong wind
Heavy rain
Early frost
Fine insect mesh, fleece, cloches or low tunnels can protect vulnerable plants. Covers should be secured properly and checked frequently to make sure pests have not become trapped underneath.
Remove or ventilate covers during warm weather where necessary. Excess heat and humidity can damage crops and encourage disease.
Plan for Protection Before It Is Needed
A few degrees of protection can make a significant difference to young autumn crops.
Prepare fleece, cloches, cold frames or low tunnels before the first cold night is forecast. Check that covers are intact and that supports are strong enough to prevent the material from pressing heavily onto plants.
Weather forecasts, cold-night warnings and frost alerts in Your Growing Companion can help indicate when vulnerable sowings may need extra protection.
Protection becomes less effective as temperatures fall further. It can extend the season, but it cannot guarantee continued growth during severe winter conditions.
Sow Small Amounts at Regular Intervals
Late sowings carry greater uncertainty than spring sowings. A period of extreme heat, heavy rain or unexpectedly early cold can affect an entire batch.
Where time allows, make several small sowings at intervals of one or two weeks. This spreads the risk and provides crops at different stages of growth.
Avoid sowing more than can realistically be harvested. A short row of leaves or radishes may be more useful than a whole bed maturing at once.
Know When It Is Too Late
Seed packets provide guidance, but local conditions should determine the final decision.
It may be too late for a crop if:
Its normal time to maturity exceeds the useful season remaining
Daylight will decline sharply before it becomes established
The ground is likely to freeze
The crop cannot tolerate the expected temperatures
No suitable protection is available
When there is insufficient time for another vegetable crop, use the space for a green manure, mulch or a planned resting period instead.
Late-summer sowing should make productive use of the garden without wasting seed, time or effort on crops that have little chance of succeeding.
Harvest at the Right Stage
Autumn crops do not always need to reach full size.
Harvest:
Salad leaves while young and tender
Radishes before they become woody
Turnips and beetroot as baby roots
Kohlrabi before stems become tough
Chard and kale as young leaves
Peas as shoots rather than waiting for pods
Spring onions at any useful size
Regular picking encourages leafy crops to continue producing while growing conditions remain favourable.
Make Late Summer Count
A successful late-summer sowing season depends on realistic choices. Start with the first-frost date, select quick or cold-tolerant crops and sow while the soil still holds enough warmth for establishment.
Protect germinating seeds from heat and drought, then be ready to protect young plants from cold as the season changes.
Even a few short rows of salads, radishes, spinach or Oriental greens can extend the harvest and keep previously empty ground productive well into autumn.
