October polytunnel
Work in the polytunnel starts to wind down in October. There are still plenty of things to do, but little has the same urgency as in the spring and summer months. Keep harvesting, keep an eye out for problems, clear exhausted plants and remember to get young plants into the ground. There are some jobs that can be spread over the next three or four months, but in order to get ahead of the game it’s a good idea to start the process of the big tidy-up.
Weather report
The first half of October might be warm and settled, but the second half of the month often arrives with the full force of winter at its back. The weather can turn cold and very wet. There will almost certainly be frosts this month and if there were storms at the end of September, these may well persist. In northern parts of the UK the weather can be as much as one month closer to winter than the south.
October jobs in brief
Tidy up
Repair polythene, frames and doors
Get most of the winter and early spring crops sown or planted
Remove dead and diseased foliage, or whole plants that have finished cropping
Provide extra coverings to extend the growing season
Watch out for pests and diseases
Keep doors closed in strong winds
Reduce ventilation and watering, according to daytime temperatures
Plant bulbs in pots
Keep harvesting
Mibuna
Mizuna
Rocket
Land cress
Winter lettuce varieties
Spinach
Oriental green mixes
Kohl rabi
Early carrots
Garlic
Overwintered onion sets
Mangetout peas
Carrot seedlings
Planting garlic
October sowing
• Sow salad leaves early in the month. Most of these will do extremely well from an October sowing and should crop from January on.
• Lettuce, kohl rabi and carrots sown now may not make much growth if cold weather sets in. In fact, in a really cold winter, they might sit at the seedling stage for several weeks. However, it’s still worth trying an October sowing. In some winters these plants will go on to produce excellent crops. Use an early variety of carrot such as ‘Amsterdam Forcing’ or ‘Early Nantes’. Sow seed thickly in drills in the border or, if you haven’t much room, sow in a large flowerpot. Seed needs a little warmth to germinate, but that should be possible with a bit of October sun. Once seedlings are up they are fairly hardy, although an extra layer of fleece can be of use. Carrot seedlings always need protection from slugs. These beasts can stay active in the polytunnel in mild winter months.
• Sow mangetout peas in pots of good compost (sowing in situ is another option, but pots seem to work best) at the end of the month. Cover the pots with a layer of bubble wrap or fleece, and keep them out of the way of rodents if these are a problem. Seed doesn’t need any extra warmth to germinate and the first green leaves should appear in a couple of weeks. If the weather is cold be patient, as germination might take a little longer. These plants will go on to produce a first early taste of summer. Pods should be ready to harvest from April on.
Top Tip
I use the mangetout pea variety ‘Oregon Sugar Pod’ and find this successfully survives temperatures below 0˚C/32˚F when grown in a polytunnel. Other varieties may be as good, but I can’t vouch for them and seed packets don’t mention autumn sowing. If you have a favourite, give it a try.
• Autumn-planting varieties of garlic are often put outdoors this month, but it’s worth growing a few plants in the polytunnel. These come up much faster than the outdoor ones and in a mild year you may get small useful bulbs in March. If there is space to leave them to grow on, the result can be large bulbs, with bigger cloves than those grown outdoors. Push individual cloves into the soil, allowing 15cm/6in between each one.
Top Tip
Garlic grows well in large pots in the polytunnel. You can stand these outdoors to grow on as the weather warms up, or you can plant out the young plants in the garden to fill gaps in rows.
The big tidy-up
Over the next three or four months, the polytunnel should be put in order so that everything is ready for the coming year. This is usually a matter of clearing all debris, scrubbing benches and frames, as well as cleaning the polythene. It might also mean washing used pots, repairing damage to the structure and sweeping pathways. The aim is to get everything as clean, clear and sound as possible. This enables the plants that are still growing to have the best chance of producing healthy crops. It also means that problems are less likely to be carried through from one year to the next.
Not all tidying has to be done in October, but it is a good idea to make a start. A diligent gardener might wash all pots this month; a busy one might stack them in the shed to wash in the New Year. That doesn’t matter much as long as the pots get washed. What does matter is the overall structural integrity of the polytunnel. Check over everything and repair holes before they spread and split the polythene in two (see January).
If doors need repairing, or replacing, do the job before they fail altogether in a winter storm.
Tomatoes
Plants should still have plenty of ripening fruit at the beginning of the month, but things can change dramatically over thirty-one days. If freezing nights are the norm, tomato plants will edge towards their end, but if an Indian summer persists, plants will continue to crop for several weeks yet. A few cool nights can be a positive thing: moulds and mildews love warm damp conditions and, although they won’t disappear altogether, lower temperatures can stop them in their tracks. Remove any diseased or discoloured leaves and expose remaining fruit to as much light as possible. Water plants very sparingly at this end of the year, and only when the surface of the soil has dried out.
Green trusses start to have a distinctly different colour as temperatures drop: they are paler, and may never ripen on the plant.
Don’t be in a rush to pull up plants, unless they are badly diseased. If cherry varieties survive a short cold snap, they often pick up and continue to ripen fruit. In milder areas it is perfectly possible to eat fresh cherry tomatoes in December.
Tomatoes may not ripen at this end of the year
Aubergines
These can still fruit into October in warm areas and if the weather is kind. Once you have picked all the fruit, remove the plants. If red spider mite was a problem it may be wise to burn affected plants.
Top Tip
To keep tender plants growing – and often temperatures might rise again after a temporary dip – provide an extra layer of covering, such as fleece or a cloche, when a cold night is forecast. In a really cold month there may be no other option than to accept the end of some summer crops, but it is worth trying to keep things going for as long as possible.
Cucumbers
Cucumbers may have hung on until October, but they won’t last beyond this month. Leaves will turn brown and plants flop at the first hard frost. Pick any remaining fruit, remove whole plants and scrub out any containers that you will use again next year.
NOTE: Outdoor varieties that are grown in the polytunnel will often crop for longer than all-female ones bred for the glasshouse.
Potatoes
Second-cropping potatoes planted in July should be growing well and will begin to flower by the end of the month. Leaves should be a healthy green colour with no signs of blight. (If tomatoes show signs of this disease, it won’t be long before any non-resistant varieties of potato are also affected.) Try covering potato plants with an extra layer or two of fleece, or use clear polythene. Even though they are already under cover, this will keep plants warm and prevent blight spores from landing on the leaves. Don’t forget to water potatoes grown in containers. Although other areas of the polytunnel may require less water, potatoes will still need enough to swell a good crop. Try not to splash the foliage when watering.
Peppers
Both sweet and chilli peppers come into their own at this end of the year. There should be delicious tasty fruit all through this month and on into the next. Most fruit ripens to a lovely deep red and chilli peppers begin to really get hot with any bit of sunshine – remember red chilli peppers are always hotter than the green version.
It’s extraordinary that pepper plants, which needed plenty of heat to start them off when young, can withstand such temperature dips in the autumn. Leaves may start to fall from the plants and there is little that can be done about this, but peppers will continue to ripen even though foliage is sparse. Water sparingly at this end of the year and watch out for slug damage and rotting fruit.
Pick peppers as and when you need them. They tend to soften and wrinkle if a lot are picked and stored.
Peppers galore
Courgettes
Plants will look really tatty after cropping for so many months, but don’t dig them up too soon. It’s worth waiting for the one or two small courgettes a week, provided the space isn’t needed for other crops. The first really cold night might see an end to production: lift plants at that point and put them on the compost heap.
French beans
A July sowing of dwarf beans should crop well into October. Climbing French varieties might still be cropping from a spring sowing, but the pods get tough after so many months. When the harvest isn’t worth the space that the crop is taking, cut off stems at ground level, and remove the haulms and any fallen leaves.
Extract the beans out of any tough pods. You can use these fresh, or dry them for use over the next few months.
Drying French beans
Grapes
Bunches will continue to ripen in a warm, sunny October, but harvest grapes while the fruit is still sound. The polytunnel can begin to smell like a winery if grapes start to split, and insects will feast on overripe fruit. Remove bunches that are past their best and pick up all fallen grapes.
Leaves will turn a glorious colour in October. Pick up ones that fall, but enjoy the display of those on the vine for a week or two yet.
Florence fennel
If you sowed fennel in pots in the previous months, get it into the ground before the end of October, with plants 20cm/8in apart and 30cm/12in between rows. If the soil is poor, dig compost into the plot before planting. Don’t let plants go short of water; otherwise they may run to seed. This plant is surprisingly hardy and will grow on for weeks yet. Watch out for slugs, which can stay active for longer in the warmer conditions of a polytunnel. These are only a problem when plants are small.
Fennel will crop over a long period. From an August sowing, bulbs can be harvested from December to May. The foliage can be used at any time, provided a plant is never stripped of leaves. Plants might need extra coverings if temperatures fall below 0˚C/32˚F.
Spring cabbage
Late sowings of spring cabbage should be planted out in October. Plants should be 45cm/18in apart – they might seem small and a bit spindly, but they will come into their own and fill out to justify the spacing in the spring. Choose a cool day and transplant in the evening, making sure the young plants are thoroughly watered in. If the soil is acid, add lime or wood ash to raise pH.
Cabbages love the spent manure from a cucumber hotbed spread around as a mulch (although lime and manure shouldn’t be allowed to mix). The nitrogen from the manure can lead to soft, leafy growth, but this is seldom a problem for cabbages in a polytunnel.
Brassicas transplant well and don’t mind root disturbance. If buying in young cabbage plants, avoid limp specimens and always check for signs of clubroot disease – lumps and bumps that distort the roots. Spring cabbage can be grown outdoors, but plants produce earlier, lush, soft leaves if they are grown in the polytunnel.
Wood ash helps raise soil pH
Winter crops
All young plants should be growing well from summer sowings. Keep them weeded and watered. They should be well coloured and healthy. Look out for slug damage. In a mild autumn these pests can destroy small seedlings, but they might also slide into the folds of a cabbage to survive the winter. Removing and destroying them now can avoid a lot of damage in the months ahead.
Lettuce and Swiss chard, sown in trays in August, should go into their final homes as crops clear from the polytunnel. Both will manage on the leftovers from a previously manured crop, but they like the soil to be dug over and loose. Allow plenty of room around chard plants, as they can be prone to moulds if overcrowded.
NOTE: Growing winter lettuce in too rich a soil can lead to problems with mildew.
Parsley does well in the polytunnel throughout the winter months. Plants raised from seed can be planted in the border or in large pots.
Top Tip
Pots of parsley plants can often be found in the fruit and vegetable section of the supermarket. If the plants are short and sturdy they will thrive when planted out in the polytunnel. Avoid overcrowded pots with tall leggy plants.
Plenty of autumn and winter crops
Why not plant a few bulbs?
Plant spring-flowering bulbs in pots in the polytunnel for the earliest blooms. You can’t eat them, but they look so lovely that they are worth a mention. Containers can be moved outdoors in the spring, but in the meantime, the foliage will benefit from the protection of the polytunnel.
Air and water
Ventilation now is as important as ever. Hot humid conditions encourage disease, but a cold wind blowing through can knock plants back. Open doors on hot days and keep them closed when temperatures fall. Remember that a door can be propped ajar to allow some ventilation, while reducing wind damage on cooler days. Always close doors overnight in October.
Watering should be reduced to a minimum now, but don’t let plants in containers dry out.
Basil
Cucumbers
Peppers
Aubergines
Tomatoes
French beans
Grapes
Fennel
Salad leaves
Lettuce
Spinach
Courgettes
Pak choi
October harvest
Some harvesting hints
• Some of the July sowings may have grown into large plants. Start picking the large outer leaves of Swiss chard, spinach, kale, etc., if desired. In any case these will often discolour and drop from the plants as the winter rolls on.
• Enjoy pak choi while the stems are young and juicy. This isn’t a very hardy plant and it may fail as the weather chills.
• When you lift tender plants, strip off all viable fruits, pods, etc. Green tomatoes will ripen indoors if left with a banana or ripe tomato to speed up the process.
Ruby chard