About Perennial Vegetables

When we started Quail Seeds, perennial vegetables were part of our vision. They have always been one of our specialties. We're happy to see them finally gaining a place in discussions about food security and low-input gardening. New books, articles, and videos on them are suddenly getting a lot of attention.

But when topics get media attention, reality gets over-simplified. As someone who has been advocating for and growing perennials for a long time, I'd like to offer some nuance and depth to the topic.

Perennials do not require yearly tillage and sowing, and can often get by with less fertility than faster-growing annuals. They can often use areas that are too shady, too full of roots and rocks, or too steep for other crops. Rhubarb, for example, produces best in areas too shady for annual vegetables. Perennial arugula can grow in soil that's drier and rockier than conventional salad greens prefer. Some perennials can produce well with just a layer of organic mulch like fallen leaves to maintain fertility. All of these qualities can make them labor-saving for the gardener and low-impact for the environment.

Fruit and nut crops are perennial crops that are already hugely successful and widely-grown in temperate climates.  Non-woody vegetables producing leafy greens, bulbs, or roots are more rare, and are generally what people mean when they talk about perennial vegetables. 

Perennial vegetable crops had an important place in subsistence homesteads and gardens in the past, and I believe they will again. But it's important to understand what that place was.

In the tropics, perennial vegetables are common and widely-used. (Tomatoes and peppers are both tropical perennials.) In the temperate climates of Europe and North America, perennial vegetable crops are rarer. Partly that's because they don't fit the sow/grow/harvest/plow pattern that dominates our agriculture. Perennials are cut-and-come-again crops, not harvest-and-ship crops.

But that isn't all there is to it. Even in ancient times, and even in subsistence situations, perennial greens, bulbs and roots are available seasonally. A plant that's going to live through the winter  must save some of its energy and biomass for its own survival. It must go dormant when conditions are too cold, or too dry, for growth, (Tropical plants have no need for cold-season dormancy, and can keep producing.) Dormancy is the key to the temperate perennials' niche: It gives them an edge over annual crops in spring, but it limits  the amount of energy the plant can put into new growth. 

In temperate climates, perennials excel at producing fresh greens while it's still too soon for annuals to produce food. In previous centuries, April was "the cruelest month" because there was nothing much to eat--the stored winter food was used up and new crops could not produce anything yet. It was called the "Hunger Gap". That's when perennial (and biennial) crops were critical. Their established root systems could send up shoots as soon as longer days  or a bit of warmth broke their dormancy. Rhubarb, Stridolo, Good King Henry, Asparagus, Sorrel, Sea Kale, Dandelion greens, Wild Chicory--all of these are eaten as sprouts or young shoots in very early spring. Many of them are delicacies.

But it is not a hugely long list. When expanding into less-known perennials, it's important to have realistic expectations. Many perennials have been grown as semi-wild or even foraged crops and haven't had the intensive selection that annual crops have. They may be stronger in flavor, tougher in texture, or have edible parts smaller than what we are used to. Like many wild edibles, they may be usable or palatable for only a short window in spring.  They may require more prep time in the kitchen than a big, clean, domesticated vegetable. Salad Burnet, Lovage, and Alexanders are examples. They are certainly perennial, and certainly edible. But in flavor they are on the border between herbs and vegetables--most people would want them as an accent, not a main flavor.

In temperate climates, perennials are a supplement, not a substitute, for annual vegetables. They offer a great alternative to intensive cultivation. They are a great way to make part of your garden low-maintenance and productive year-round--not because they bear year-round, but because they bear when annual crops cannot.

In the future I think they'll play a bigger role, partly because of the search for low-till, low-input alternatives. But also because more people are growing them and saving seed. Our annual crops are varied, big, succulent, and mild-flavored because they've been grown and selected over the centuries for those qualities. As perennials are grown more, they will diversify and be shaped to suit people's desires.  They will have larger yields. In turn, more people will grow them. We can be the generation of gardeners to re-start that process.

Choosing which Perennials to Grow--and How to Grow Them

Perennials from various climates that have been cultivated for a long time--especially if they've been cultivated for market--have lost their wildness and become easy to sprout and grow. Sorrel, bunching onions, erba stella, rhubarb, asparagus, artichoke, and chives are as easy to grow as annual crops, produce abundantly, and are choice edibles. 

In mild climates, where plants don't go all the way dormant, some will perennialize. Tree Collards and Perpetual Spinach are examples of leafy greens that produce over a very long period and are native to mild maritime climates. Quite a few varieties of collards and kales produce a percentage of perennial offspring. Celery, chard, and arugula all have perennial varieties. Artichokes are classic Mediterranean perennials. With these, the limitation isn't getting them to sprout, it's getting them to survive the winter. Good drainage is often key to carrying these mild-climate plants through  winter. They do well with compost, sun, and a porous soil. On clay, it's often best to make a mound with rock, soil, and plenty of compost then plant on that for good drainage.

Lovage and Alexanders are celery relatives that are still partly wild;  they need cold-conditioning (stratification) before germinating. But given moist soil and time, they sprout pretty well. The easiest way to do that is to plant them in fall or very early spring. Or the damp seeds can be chilled  in the fridge. They both do well in semi-shade. I have them just outside the canopy of fruit trees, where the soil is moist and fallen leaves make an effortless mulch.

I imagine rhubarb evolved along streams in woodlands, where they would have the semi-shade and rich moist soil they love. Every few years, you should dig up and separate the crowns (which should have multiplied.) When you replant, dig a deep hole and fill it with the richest food you've got--manure, unfinished compost, food waste, grass clippings, alfalfa meal, fish waste--you get the picture. In Alaska we used fish guts and got beautiful big stalks. The smellier the fertilizer, the deeper you need to bury it to keep animals away. But rhubarb will go deep enough to find it--I've seen it make roots as big as a man's leg.

Wild or perennial plants from northern regions can be challenging to even experienced gardeners:  Good King Henry, Spinach Vine, and Alpine Strawberry are good examples. They are programmed to stay dormant through the winter and sprout, a few at a time, in spring.  Success with them depends on mimicking that schedule, so they too should be planted in pots outdoors in the winter. They will do best in woodsy conditions of shade and soil. Strangely enough, true dandelions are also a challenge to sprout when and where you want them. Their seeds can go dormant in the soil for long periods, and sprout a few at a time over a period of years--a great pattern for a weed, but not for the kitchen garden.

The usual method of fertilizing perennials and controlling weeds is to apply mulch to the soil around them. Fallen leaves are ideal, so if you have fruit trees or broadleaf shade trees, this is an excellent use for the autumn leaves. Wood chips (Use chipped branches for preference rather than the trunk wood) are another good mulch. Straw, compost, or even dead weeds are fine, but do not use spruce or cedar needles, Black Walnut leaves, decorative bark, or plastic.

Spruce, cedar, and especially walnuts contain compounds that act as natural herbicides, weakening nearby plants. Some plants (Many bulbs, beans, bluebells, corn and squash for example) are immune to the poison, but most are not. If you do have black walnut trees, perennial edibles that can thrive under or around them are currants, elderberries, miner's lettuce, multiplier onion, bunching onion, and wild plum. I have a hedgerow with elderberries, currants, comfrey, walking onion, and miner's lettuce on the shady end, and sage, perennial arugula, catnip, and feverfew on the sunny end.
The whole hedgerow grows in walnut-tainted soil, but the shady end is right under the walnut canopy. Grass will grow under walnuts as well, so it's a very pleasant shady refuge in summer.

The hedgerow plants have a lot against them--in shade, coping with herbicidal compounds from the black walnut, and in soil fully colonized with tree roots--yet they survive and thrive. That is what's possible when you broaden your choices past the usual annuals and fruit trees to include less-common trees, shrubs, herbs, and perennial vegetables that are adapted to your conditions.