5 Care Tips for Overwintering Crops

12 December 2019, written by Benedict Vanheems

At this time of year growth in the vegetable garden has finally ground to a halt. It’s not especially cold, at least here, but the lack of light and claggy, sodden soil doesn’t make for the best growing conditions. The shortest day of the year is fast approaching, and the few crops that remain in the ground are the hardiest of the hardy. Chard, kale, leeks, a few scraggly stands of sprouting broccoli and a shivering scatter of winter salads will provide frugal pickings between now and spring.

Here are five ways to get the best from your winter stalwarts…

1. Make the Most of Available Light

Light levels in midwinter, particularly in overcast climes like mine, can be depressingly gloomy. It’s enough to leave you feeling under the weather, but spare a thought for our struggling plants!

There’s a simple way to make the most of what light there is, and that’s to allow a little more room between plants than you ordinarily would. More space means better light penetration to the leaves. For most clump-forming salads this means leaving about 25cm (9in) between plants in both directions. This would be excessive during the growing season but it gives plants a greater shot at snatching a few precious rays of sunshine, and should make a difference to how many leaves you’ll get to pick.

“Overwintering — Wider than normal spacing helps plants to access enough light to grow well over winter

2. Water Less

If you grow in a mild, maritime climate like mine you probably haven’t watered outside since early autumn – and won’t need to until well into spring! But watering continues under cover and in warmer regions. It’s important to find a balance between keeping plants quenched and not allowing them to sit for extended periods of time in damp, humid conditions.

In an unheated tunnel or greenhouse, when temperatures are particularly low and the sun really isn’t shining that much, you may get away with watering only every two to three weeks. Let the soil dry out between waterings to minimise the risk of mildew, moulds and those menacing molluscs, slugs and snails. Then as the days begin to lengthen and temperatures become noticeably less chilly, you can pick up the watering in line with the easing conditions.

3. Support Wind-Blown Brassicas

Winter storms can play havoc with long-suffering brassicas such as kale and Brussels sprouts. Weather-beaten and shoved hither and thither by the wind, the tallest plants will benefit from a little extra support.

Mound up soil around the base of stems to anchor swaying plants in place. Top-heavy specimens may benefit from being tied to a sturdy bamboo cane or stake, thrust into the ground deep enough to keep it rigid. Use soft garden twine or raffia to minimise rubbing.

Brassicas are especially prone to pigeon attacks over winter – and who can blame them when food is so thin on the ground? You might tolerate a little damage to keep our feathered friends going, but if the damage gets too severe remember that simply covering plants with mesh or netting will keep them off.

4. Protect Plants from Cold

It’s amazing how much difference a little crop protection makes. Solid structures such as a tunnel or greenhouse extend the growing season by two months or more. By trapping more of the sun’s warmth for longer, mild days outdoors are turned into warm days under cover, dramatically speeding up growth and the frequency of harvests.

Outside crops can be coaxed into action too. Horticultural fleece or row covers won’t hang on to heat for long enough and they can become sodden and heavy, pinning crops to the ground and keeping them chilled. Low tunnels of clear polythene will help to keep many different vegetables ticking over including overwintering onions, leafy greens such as spinach, and maincrop carrots and beetroots awaiting harvest.

Or drop cold frames into place over salads like lamb’s lettuce (mache or corn salad) or hardy herbs such as coriander or parsley. Barbara Pleasant suggests the added precaution of throwing blankets over tunnels and frames on the very coldest nights, to keep plants from freezing to death. Covers also help to shield plants from nibbling ne’er-do-wells such as deer and rabbits.

“Frosty — Some crops like this chard stop growing in winter but provide an early spring harvest

5. Be Patient

Many vegetables just stop growing altogether during winter, and there’s very little you can do about it. Chard is one of those remarkably hardy staples that after a final few leaves in early winter shuts down for two months, only to push out the first tender leaves of the season as the earliest spring bulbs come into bloom.

Waiting – patiently – for the first fresh leaves of the year builds anticipation. It’s a soothing antidote to the instant gratification we’ve come to expect in modern life. Then when they arrive it’s a joyous moment indeed! While it’s great to keep the party going for longer, sometimes a little break helps us appreciate the value of what we’ve got. Those long-awaited pickings are one of life’s simple pleasures.