Winter tips: Caring for the soil

Easter holidays; a few promisingly warm days when the bees start flying, birds singing, and a green haze begins to drift across the bleached colours of winter. And then comes the lambing snow, and the old adage chimes as a warning to those whose green fingers are too keen: “Ne’er cast a clout, ‘till May is out.” Whether “May” refers to the month, or the flowering of the hawthorn, the message to growers is essentially the same: don’t get ahead of yourself. Don’t be fooled into believing we have left winter behind. Not just yet.

So what can we do at the moment, that won’t all go to ruin in a late storm or frost? Windowsill sowings of seeds seems like a good idea, and brassicas are something to focus on at this time of year, for now is the time to sow brassicas for next winter. Recommended varieties for Skye are “Nautic” for sprouts, “Westland Winter” for kale and purple sprouting broccoli “early”. There are also quite a few heritage varieties that grow well on the west coast. “Sutherland Kale” was a lost variety, recently rescued, that tells a wonderful success story to support the importance of seed saving 

Soil and Climate Change

Through photosynthesis, plants convert carbon dioxide in the atmosphere into carbohydrates, up to 40% of which are secreted from their roots. When mycorrhizal fungi and bacteria consume these carbohydrates they are locking away carbon in their cells, which can remain intact in the soil for hundreds of years. Soil is a massive store of captured carbon as this video explains.

Regenerating the world’s soils by restoring the functioning of their microorganisms can soak up huge amounts of atmospheric carbon, perhaps even taking CO2 levels back to safe levels that would stabilise global temperature.

Caring for our soil

Ploughing and digging interferes with the soil’s organisms and soil structure, throwing the food web out of balance. In unbalanced soils, beneficial microorganisms can be boosted by applying various home-made brews. Here is a fun video  from Australia.  

Practicing no-dig methods helps to preserve soil structure and the complex relationships between soil organisms, enabling them to get on with the work. Charles Dowding, a leading practitioner of no-dig methods, has carried out trials of dig and no-dig beds for many years. These show that no-dig produces very healthy plants and as much, if not more food, with less work and less disruption of the soil ecosystem. 

Cardboard has many uses in the garden. It is ideal for creating new beds using the no-dig method. Dig out any perennial weeds such as docks or brambles, but leave the rest. Lay down overlapping sheets of plain brown cardboard with any plastic tape removed. Weight down with 15 cm of compost or well-rotted manure and leave for six months. Or if the season is right for growing, you can plant seedlings straight into the compost.

Mulches

The winter is a good time for mulching. Covering your soil with compost, leafmould or other organic matter such as seaweed allows frost to break up larger lumps so soil organisms can get to work, and stops winter rain washing away the soil. If you still have crops in the ground, spread the mulch between them. If the beds are bare, you can put sheets of cardboard on top of your mulch – the worms will enjoy both, leaving you with a lovely crumbly surface to plant into next spring. 

Leafmould is easy to make

  • collect fallen autumn leaves (avoid evergreen leaves as they take longer to break down).
  • put them while damp into a re-usable sack (pierce with a few holes if plastic) and tie the top. Or you can make a container of wire mesh, or twined plant stalks, held up by posts.
  • leave for a year or two until the leaves have decomposed into a crumbly, dark substance with no leaf structure remaining.

Spread leafmould on your vegetable beds, add to the compost heap, or use it to make your own potting compost. For seed compost use either well-sieved leafmould on its own or mixed with equal parts sharp sand. For growing seedlings, mix equal parts leafmould, sharp sand, loam (soil), and garden compost.

Autumn leaves rot down best under cool conditions through the action of fungi. Adding a lot of leaves to your compost heap will slow down the bacteria-driven decomposition, so it’s best to compost leaves separately. Lignin from the decomposed leaves is useful for soil health. It regulates mineral flows within the soil, and can hold soil nutrients in reserve.

Composting

Composting your vegetable waste recycles the nutrients absorbed by your crops back into your garden soil. You can compost in wooden bays (use upcycled pallets), purpose-designed containers or just a pile on the ground. The main thing is to avoid too much moisture getting into the compost heap, and retain the warmth generated by the bacterial action – a covering of old carpet or other insulation helps in both respects. Make sure the base allows drainage and air can enter the heap. Then build the heap with layers of 25-50 percent soft green materials (grass clippings, annual weeds, vegetable waste or manure) and the rest consisting of woody brown material (prunings, wood chippings, paper, cardboard, straw, dead bracken). To speed up the process you can turn the heap every few months.
 

compost bins from upcylced pallets

For more information on how to compost, watch three short videos by MooFood:
What is compost and why is it important?
What you can and can’t compost
Different ways to compost

Preparing for next year

Take advantage of this quiet time in the garden to plan what you’d like to grow next year, and where in the garden. Look at seed suppliers (if you haven’t saved your own) and get together with others to share and swap seeds – try something new!  Suppliers such as Real Seeds and the Seed Cooperative produce open-pollinated seeds and encourage people to save their own seeds.

Training and learning

Check out the excellent online training courses offered by West Highland College to increase the productivity of your garden.

The courses are run by experienced growers who are familiar with our west coast/Highland weather and soil conditions. See the events section of our website for upcoming courses.