A place to explore and buy perennial vegetables and other food plants.
Perennial vegetables don’t necessarily need a lot of feeding. They are often less hungry than annual vegetables because their deeper, more extensive root systems can mine more soil for food. And because they are less likely to have been bred to grow as much as possible in a short time.
But a bit of deliberate feeding will enrich an impoverished soil (if you have one), help the vegetables produce big bulbs, roots and tubers and keep up with continuous harvests of their tasty leaves.
Most, if not all, of the feeding materials can be produced on site removing the need for the cost and the carbon emissions associated with importing manure and compost.
Let me count (some of) the ways….
Martin Crawford (author of ‘How to grow Perennial vegetables’) estimates that because perennial vegetables are less demanding than annual vegetables you only need to devote 10-15% of the land to growing ‘green manures’ compared to the 30-50% that annual plants require.
10-15% of the land for growing green manure can largely be achieved by growing perennial white clover on path areas. Clover, being a legume, is able to get nitrogen from the air via nitrogen-fixing bacteria which live in nodules on its roots. Much of this nitrogen will find its way to the leaves of the clover. To release this nitrogen, rather than digging in the path each year, cut the clover at intervals through the summer and use the clippings as mulch around adjacent vegetable plants. The process of cutting the clover will also cause the plant to shed root material to maintain the optimal shoot to root ratio.
Clover is good; but I’ve learnt that a mixture of green manure plants (e.g. white clover, red clover, ryegrass, chicory, cocksfoot) is better and, amazingly, gives more than the sum of its parts. Choose plants which can stand being walked on and mowed.
Fairy fern, Azolla filiculoides, is a nitrogen-fixing aquatic fern. It is easy to grow it in buckets and add scoopfuls to the base of individual plants (including those in pots). Don’t allow it to spread to natural ponds and waterways where it can become invasive and a serious problem, and protect it from frost in the winter.
Comfrey is a particularly fast-growing and effective mineral-accumulating plant. Its deep roots extract minerals from deeper layers of soil, incorporate those minerals in its upper parts and release them when it is cut. Its foliage can be chopped down and added to the soil surface as a mulch around vegetables (particularly easy to do if it is planted nearby). It can also be made into a liquid feed by compressing it in a bucket, or added to the compost heap as an activator.
Shrubs or trees have particularly deep roots of course and return minerals to the soil when their leaves fall and break down on the surface of the garden soil. Collected leaves left to rot in compost bags or chicken wire enclosures give supplies of mineral-rich leaf mulch.
Compost can be made in free-standing heaps but an insulating bin of some sort is more efficient especially for smaller volumes.
The material in compost heaps is initially broken down by bacteria. Worms and other animals may add to the decomposition when the heap cools down. Setting up a bin with ideal conditions for worms is another way to breakdown organic matter (and is a particularly useful way to deal with kitchen waste). Similar set ups can be designed for other creatures such as snails and soldier flies (the latter are used in the US).
Of course heaping up compost materials or leaves to decompose, setting up a worm bin or chopping and dropping comfrey around the garden is simply making deliberate use of processes that allow mature communities of plants to be self-sustaining.
So another approach (and ultimately an easier one) is to encourage the garden to move towards self-sustenance. Nitrogen-fixing plants grown amongst the vegetables will release nitrogen naturally when they drop their leaves or die down to the root in winter. Nitrogen-fixing legumes (rhizobial plants) can be as used as ground-cover (e.g. yellow trefoil) and as bee plants (e.g lupins) etc. Some may be vegetables themselves.
In the same way, mineral accumulators such as nettles, dandelion, rhubarb, lucerne, turkish rocket, horseradish and scorzonera can be added to the plant mix. (All of the plants in that list are vegetables but there are also mineral-accumulating herbs, insect-attractants, scented plants, ornamentals etc. which all have valuable roles to play).
If the garden is dominated by perennial plants and the soil is left relatively undisturbed, mycorrhizal fungi will develop in and around the plant roots and provide their host plants with minerals in exchange for carbohydrates. In time a huge network of fungal threads can move nutrients from one area of the garden to another.
Nearly all trees and shrubs (as well as some annuals and many herbaceous perennials) form mycorrhizal associations and of course planting trees and shrubs has the additional benefit of giving plentiful leaf litter to breakdown where it falls on the soil surface. There is also a group of non-leguminous nitrogen-fixing shrubs and trees (actinorhizal plants), such as the edible berry-bearing shade-tolerant Eleagnus species, which are especially useful to include.
I’d like my perennial vegetable garden to be self-sustaining in time. I’ve got a way to go. Chopping and changing the planting in the process of seeking plants that work well together inevitably leads to soil disturbance as does digging out patches of over-dominant weeds. But the perennial vegetables and flowers, hedges and fruit trees on the site are getting more mature and fungi are becoming a common site in the less disturbed corners.
In the meantime I make use of garden compost, leaves from the nearby cemetery, worm compost, clover from the paths and also, when I’m being organized, yet another way, urine from the bathroom, which diluted makes a balanced liquid feed and top-notch compost activator.