We tend to think of plants developing their edible crops in the spring and summer. This seems intuitive given that spring is associated with new life after the harsher conditions of winter, and the fact that many animal species give birth to their young in the spring, giving them the maximum time to feed up and grow before the relative privations of the colder months of the year. And indeed, many crops are ready for harvest in the warmer times, with the longer days giving them more sunshine and so energy to ripen. But there are also plenty of vegetables that can be harvested in fall and winter, including some of the most nutritious of all veggies. Incorporating some of the following plants into your permaculture design will ensure you have access to fresh vegetables throughout much of the year, and that you have a diverse and nutritious range of ingredients for your kitchen.
Given a soil rich in nitrogen and potassium, along with sufficient moisture, cauliflowers will thrive and be available for harvest up until the first frost of winter. Mayflower and Aalsmeer are good varieties for providing good winter crops. Look for flower buds that are tightly closed and cut off just below the head. If you experience an unexpected overnight frost before you have harvested, the heads will still be okay to use if you cut them when frozen and use straightaway; it is only if the heads freeze, thaw and freeze again while still on the plant that they will spoil.
While Jerusalem artichokes are actually a distant relation of the sunflower, they can thrive when the days draw in and the temperature drops. With the edible part being a tuber that grows below ground, it is protected from the harsher conditions of winter. Late in fall the leaves of the artichoke plant, which are above ground, will turn yellow, as the plant matures. Prune these back to around 3 inches long, but place the cuttings over the plants to act as insulating mulch. Be aware that any plants are left in the ground over the winter they will regrow into large plants the following spring.
Brussels sprouts are arguably the hardiest of vegetables; they certainly are the among the cabbage family to which they belong. In fact, going through a couple of fall frosts will actually enhance the sweetness and flavor of the crop. Brussels sprouts are also adaptable in that you can harvest some of the crop when the sprouts are small earlier in the season (the smaller ones taste sweeter) and leave others to mature further on the stalk for harvest later. Typically you will want to harvest the mature sprouts before the ground freezes, however, if you experience mild winters, Brussels sprout planting can be staggered to allow for harvests throughout the colder months.
Leeks are an ideal winter crop as they are genetically programed to survive the winter months in order to produce seeds the following spring. Fortunately, they can be harvested at any time during the colder months. The only criterion for a successful crop (as with all winter vegetables) is to prevent the ground where your leeks are planted from freezing. You can do this by adding plenty of mulch, typically in the form of straw, to your garden beds. Varieties such as American Flag and Blue Solaise work well as winter crops as they have thicker stems and shorter leaves, which enable them to survive cold conditions. You can harvest leeks at any size, with the smaller ones having a subtler flavor, and so have access to them throughout the winter months.
The thick skins that characterize winter squash allow them to thrive in cold conditions, the softer flesh inside protected from the chill. This protective shell also means you can store them – in a cool dry place – for quite a long time after harvest. There are lots of different varieties that are suitable as a winter crop, including Acorn, Butternut, Hubbard and Blue Hokkaido. All are heavy feeders so require a lot of soil nutrients. When planting add a good does of compost to the soil, and mulch your crops well to ensure they are sufficiently fed. After harvest, place in a warm, dry place for a week to cure the vegetables before use.
Parsnips have a relatively long growing season, so you should look to plant seeds early in spring, soon after the last frost of winter, to give the crop the maximum time to mature for harvesting in winter. They do not need as much compost as many other vegetable plants, and you should avoid adding fresh manure to the garden beds parsnips are in, as this can cause them to split, resulting in less viable crops. Sow little clusters of seeds and thin out the seedlings to leave the strongest in each cluster. Parsnips are at their best if they experience a couple of weeks of near0-freezing temperatures – this causes the starches in the vegetable to turn to sugar, adding to the flavor. You can also leave parsnips in the ground throughout the winter and harvest after the ground thaws in spring. Guerney and Cobham varieties are good choices.
Even though it is a leafy green, kale actually prefers cold weather, and experiencing a touch of frost can add to its flavor. They prefer slightly alkaline soil and a lot of moisture, so water regularly (they may also benefit from drip irrigation, but be careful not to use such a system through the winter as the pipes can freeze). You can harvest kale leave sat any point after they are approximately 8 inches long, so you can regularly take leaves from an individual plant throughout the season. You can also take a whole plant and, if you leave the rootstock in the ground, you should get new growth within a couple of weeks. Tuscan and Squire are popular varieties for a winter kale crop.