Late Sowing Seeds and Planting Out

I get quite a few emails on the lines of ‘Is it too late to plant..?’ And when we’ve had a wet and cold start to the season the number of growers behind with things goes up. The thing is it depends on what the crop is, how it’s grown and what the weather is going to do. My general rule is to give it a go but don’t bank on it succeeding.

Growing under cover in a polytunnel or greenhouse does extend the season but only by a few weeks.

Seed Sowing

Seed Sowing – Better Late than Never?

Late Planting Potatoes

Potatoes are a pretty safe bet for late planting so long as they have time to produce a crop before the frosts arrive. That means you’ve more time with an early maturing variety taking 12 weeks than a late variety that may take 22 weeks.

Having said that, late plantings are going to be late to harvest and so more likely to be hit by potato blight which tends to strike later in the year.

Sadly no chemical controls like Bordeaux mixture that served us so well for many years are now available to gardeners. I know a lot of gardeners still mix up their own Bordeaux and Burgundy blight sprays from copper sulphate and lime or washing soda – all of which are available.

Late Sowing Parsnips

With parsnips the problem is that they take a fair time to mature – typically a 100 days from sowing. Speeding up germination by sowing in biodegradable pots under heat for 7 to 10 days or chitting helps. When the soil is cool it takes longer for the seed to germinate. This extends the period from sowing to harvest away from the optimum.

Although parsnips are hardy, growth will slow and cease as it gets cold towards the end of the season.

Late Sowing Sweetcorn

Sweetcorn used to be a tricky crop in the UK, requiring a good long summer to produce a crop. Hence growing advice concentrates on how to get it started early to gain that ‘prime growing time’ Now it’s more tolerant of the British climate and even a mid-June sowing stands a good chance of producing a crop.

Late Bulb Onions

Bulb onions are different to most other crops in that their growth is controlled by day length. They grow from seed or set and then start bulking up when the day length is around 14 to 16 hours.

Bulb onions have little tolerance for late sowing or planting.

Late Planting Garlic

Garlic is another crop with little room for manoeuvre. You can snatch a couple of weeks back by starting or even growing completely in pots under cover. However, generally after March they’re not going to do very well.

Late Leeks

You can get away with sowing leeks as late as May so long as you accept you’ll only get small leeks nearer to spring onion sized than normal leeks. Of course, chefs prize baby leeks so you can claim that was your plan.

Late Tomatoes

Indeterminate or cordon tomatoes sown late may well produce a reduced crop. They’ll probably need stopping before they’ve produce their usual number of trusses. Remember that as the season draws to an end with cooler and more humid weather, the plants are more likely to succumb to fungal diseases and, of course, blight. Still, a reduced crop beats no crop.

Determinate tomatoes are different in that they produce most of their crop in one flush. If frost or problems hit before the fruits are ready then no crop.


Generally cucumbers are sown between March and May. The latest I would consider sowing is mid-June and that’s pushing it. For speedy germination, start under heat between 25ºC and 30ºC

Leafy Brassica Planting Dates

With the leafy brassicas; cabbage, cauliflower, calabrese etc. there’s a wide range of varieties which have been developed for growing at a specific time of year.   Fast kinds that crop in the same season as they’re planted and over-wintering varieties that will slowly grow for an early crop the following year.

The seeds will keep if stored well and I would suggest obtaining a variety bred to be sown when you are able.

Broad Beans

Broad beans actually like a cooler growing season. Planting late means the crop is hit by hot weather when the pests are at their most active. Generally you can get away with a few weeks but be aware a lot depends on the weather.

Some varieties like Aquadulce Claudia can be sown at the beginning of winter for an early crop the following year as well as in early spring.

Runner Beans and French Beans

Runner and French beans are normally sown in April, May and early June. They are not hardy and frost will kill them so timing is important. Starting in pots under heat (27ºC optimally) will speed germination and give a little extra time. Another tip is to soak seeds in water at around 20ºC for half an hour prior to sowing. This softens the seed’s hard protective shell helping germination.

Posted in Allotment Garden Diary
3 comments on “Late Sowing Seeds and Planting Out
  1. Stuart Broadley says:

    Excellent information good to know its not too late

  2. Margaret E Johnson says:

    Thanks for this. I have started seeds early in pots and been disapointed on transplanting because of cold nights. I have Butternut squash in pots still, but planted out some climbing beans a couple of days ago. Last night/ early morning must have been cold here in Sheffield as my heating came on automatically. I have more beans set in pots in the greenhouse for a second backup planting. The Slugs are having a great time, until they get into the yeasty lidded yogurt pots, through the holes in the side. The adverts don’t seem to be too bad on this article.

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