Autumn is well and truly upon us. The rain has been welcome, and the lower temperatures at night are warning plants and gardeners to focus on preparing for colder weather. While a hard frost is unusual during October it can happen, and even a light frost will kill or damage some tender plants.

Plants have some fabulous mechanisms for responding to changes in their environment or to changes at different times of year as the seasons change. As gardeners we might at times wish to support those responses to ease the plants’ transition. Do keep an eye on weather forecasts. They are not always accurate but might give you a good idea of the temperature to come. Couple this with your knowledge that on a clear cloudless night with no wind, the temperature will drop quickly. It’s time to prepare! Most houseplants should have been taken indoors by now, preferably not straight into a warm room. Help them to adjust to new conditions by moving into a cool shelter first eg a cold frame or a cool room in the house. After a week or so, move them again if they are going into a warmer room. Remember, adjusting takes time. Tender bedding plants in tubs and hanging baskets may still be flowering well, enjoy them as they are on borrowed time. Most bedding is not frost hardy and will die. Some, such as pelargoniums (geraniums) and fuchsias can be overwintered in a cool indoor location so be sure to take them in before they get frosted.

With a long dry spell and then recent rain, some outdoor shrubs are now sending out new growth. This growth is very tender even if the shrub itself is tough, so if you want it to harden you will need to have a fleece handy for protection should frost threaten. Remove the fleece during the day if it is likely to be a single frost event so that the plant continues to grow progressively hardier. If it is only a light frost, I let most plants take their chances until we have had numerous cold nights. The plants will have time to employ their hardening mechanisms and toughen up. The hardy plants will ready themselves for the very cold weather on the way, and I feel it is better not to molly-coddle them. Alarm bells ring if a sudden drop in temperature follows a fairly mild period. I would put a fleece over tender plants I want to save. A moist soil is said to ameliorate the effects of frost. I haven’t put this to the test as I can’t remember having anything other than a moist soil at this time of year. Some vegetables need no help, but frost might be the signal that it is time to lift the crop. Beetroot, cauliflower and tatties will need lifting or protecting. The brassicas (cabbage, broccoli, brussels sprouts), spinach, leeks, parsnips, and carrots will stand harsh weather, but consider if they are at risk from other forces, such as the dreaded voles. It may be safer to lift and store them. Chard normally stands a good few months after the first frost but last winter ours was badly damaged as the first frost was moderate and sudden—there had been no gradual drop in temperature for the plants to get their protection in gear.

Mulched soil, with or without the crop will trap some of the soil warmth. This benefits the crop and is good protection for the soil organisms, to keep them active for as long as possible till the cold really sets in. The more tender crops grown outside or under cold glass are now vulnerable. Lower temperatures alone may be enough for them to stop further fruit development or ripening, so be observant and make a judgment call on when to harvest all the remaining fruits on your tomatoes, courgettes, pumpkins, French beans, basil and chillies. Those in containers could be moved indoors, and some fruits will continue to ripen after picking. Covering with fleece will trap some warmer air around the plant and keep the soil temperature a bit higher for a short period. Do not use polythene laid onto the crops as this traps moisture which can encourage fungal and bacterial rots, but polythene cloches are fine as they allow for air movement.

Plastic or metal containers painted black and filled with warm water will radiate the warmth overnight, giving a little protection within cold frames or in cloches. I harvest my chillies by uprooting the whole plant and allowing the leaves to wilt. Unfortunately some leaves stubbornly cling to the plant and need snipping off, but it’s not a bad job. They are then hung on hooks in the kitchen and other rooms, giving a bright cheery atmosphere. They will continue to dry and will keep for several years. Tomatoes and the rest are made into soup or chutney. Tatties and most of the carrots are normally lifted to prevent predation. Some are left in the ground and used before I delve into the stored crop. Parsnips seem to survive in the ground pretty well with only slight damage. Tatties can be put into woven, breathable bags and stored in a frost-proof garage or shed (pictured). A few may suffered chilling injury in very long cold spells, but most are fine. We layer our carrots in a wooden box with any material that comes to hand, as long as it allows them to breathe but keeps them lightly moist. I would avoid soil, but old compost which hasn’t contained diseased plants is good, as are bark, chippings or grit. Beetroot can be treated the same way. Don’t let the individual vegetables touch one another, and don’t store damaged or diseased vegetables. Check them regularly, remove any that have started to rot, and add a sprinkling of water if the medium is too dry. If there are signs of rodent attack, wrap the containers in wire netting. If you have a large number of root vegetables you could make a clamp outside on a well-drained site. Put down a thick layer of straw, put all the tatties/carrots/etc into a heap on top, then cover the heap with another good layer of straw. Make a chimney at the top with straw which will stop a build up of moisture (which encourages rotting). Then dig a trench around the clamp, slightly out from the edge of the clamp. Heap the soil onto the straw so that you end up with a well-covered clamp. A little straw may stick out here and there but it should mostly be well covered. You can open up the clamp during the winter to get the week’s vegetables out, check for any rots or rodent damage, then seal it up again.

All vegetables stored at outdoor temperatures will need air flow to allow them to respire. They also need protection against excess moisture and cold. Some apples don’t store at all. Those that are picked before mid-September are best eaten right away.
Those that ripen after that point and are ready to pick from late September should store well in a frost free shed, around 4C is ideal. If you find some are starting to go wrinkly, pop a few (not many) into a polythene bag with holes to maintain the moisture.
If you have eaten most of your produce then store those few that need lifting before the weather turns in a carrier bag in a cool shed or swap them with others. Home grown vegetables are always appreciated!
Don’t forget to take stock. Consider what crops were a success, and which weren’t. Try to work out the whys and wherefores, it will help you to hone your gardening skills.
Happy harvesting.