Hunkering down for winter

Raised bed covered with horticultural fleece

As the leaves leap from the trees, temperatures take a turn for the nippy and the growing season grinds to a full stop, it’s time to think how best to prepare our growing spaces for winter rest. Unfortunately, cold temperatures and short days won’t allow many vegetables to grow, but there are other things we can be getting on with to ensure a great start in spring.

Winter-growing kale

You might have planted some hardy greens like kale, perpetual spinach, chard, winter salads or purple sprouting broccoli to get you through the winter. These should withstand the coldest of frosts and provide you with some added nutrition when the cupboards are down to shop-bought produce only. A good idea is to protect it with a horticultural fleece, which will take the biggest hit of the frost instead of it damaging the leaves.

If you have a raised bed that has finished growing your summer crops and it’s currently sitting empty, it’s time to protect it from the cold to come. To be more precise, we’re protecting not the frame, but the soil life within. The millions of microorganisms which live in the soil will slow down their metabolic activity during winter, but the core of the raised bed will remain a little warmer than the outside. In that core, the helpful little critters will still be processing small plant parts, broken roots and other pieces of organic matter, all to be digested and turned into plant food for the spring crops. We can play a vital part in this process by adding organic compounds for them to chomp on, and by protecting them from the worst of our British damp and cold.

On the left, a mulched bed. On the right,  indoor winter brassica seedlings.
L – mulched bed. R – indoor winter brassicas

Traditionally, all allotment holders and gardeners incorporated organic matter to their land by digging it in, with the idea that the new organic matter should be mixed with ‘spent’ soil. Luckily, this back breaking job is not only unnecessary but also a bit counterproductive. The same effect can be reached by simply placing a layer of mulch on top of the growing area, like a duvet, and leaving it for the worms and other soil animals to mix up with the soil below. This process allows the animals to create their own corridors in the soil which helps water and air to get to the lower levels, rather than sitting on the surface. Ground rich in organic matter and soil animals retains large amounts of water effectively – you’ll rarely hear about flood waters demolishing forests, but often arable, monoculture-type fields instead. This layering method has been used in permaculture for years, and most recently has been popularised by No-Dig guru Charles Dowding. Leaving a layer of mulch on top of the bed not only adds essential nutrients to the soil for next year, it also helps to protect the topsoil from freezing and allows worms to ‘work’ the cover into the lower layers. By spring, you’ll be left with nice, fluffy soil and a thin layer of mulch to protect the soil from drying out too fast in the summer heat.

If you’ve been growing for some time, you may have a composting system in place. The ready compost from your bin is an excellent mulch to add in autumn. If there are any larger, unbroken pieces in it, you can use a garden riddle to sieve these out and put back in the compost bin, or leave on the bed and use a layer of cardboard to cover this up. The worms then have a ‘double’ protection and can break the larger pieces further, without freezing their bits off.

A bed of broad bean seedlings - an easy way to check for the presence of aminopyralid in manure.
A bed of broad bean seedlings – an easy way to check for the presence of aminopyralid in manure.

Another excellent mulch to apply to your raised beds in autumn is well-rotted horse manure. In rural areas, there are many places that will allow you to get some manure for free, so ask a friendly farmer or an equestrian centre if you can grab a few bags. There is a slight risk here though: some animal manures might be from animals which have been treated with antibiotics, which isn’t exactly a problem for the plants, but some people prefer not to have such things on their food. Worse though, some manures can come from animals fed on hay treated with aminopyralid, a herbicide which will remain in manure and likely affect your crops. So, you may want to ask some questions before you apply it all over your plot. If you’re worried about aminopyralid, you can do a quick ‘patch test’ to see if there are any traces of it. Mix your manure and compost in equal parts and plant a few beans in it. They will come up on a warm window sill, and if they look healthy and have no deformities in leaves or stem, your manure is safe.

Fallen leaves are another good source of winter cover (although these are best covered with cardboard to avoid flying away), old woodchip that you might have had on paths through the season, or if you have no access to any of the above, a layer of newspaper, cardboard or a weed-stop membrane will do just fine.

A bed of kale showing a winter-growing fleece tent.
Winter-growing fleece tent

November and December are great months to put these finishing touches to the garden, before the cold and wet weather turns the paths into muddy traps and the frost makes the ground too hard to get any weeds out. And once this is done, it’s time to sit down by the fire, get a cup of nice tea or mulled wine, browse the seed catalogues, and start planning and dreaming of spring.

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