Happy Urban Dirt

Think about how much work your perennial flower beds require compared to your annual vegetable garden. In a busy year, your perennial garden will largely flow, despite neglect. Once your perennials have established themselves and are adapted to your climate and site conditions, they can be virtually indestructibleAs we all know, an annual vegetable garden requires a lot more watering, weeding and work to get a good harvest.

Once established, perennials are often more resistant to pests because of the energy reserves stored in their roots. Their deep roots and soil-building ability make them more self-sufficient in terms of watering, and their canopies, which leaf out much earlier than annuals, are better at suppressing weeds. What else can these extraordinary plants do?

The following excerpt is from Perennial vegetables By Eric Toensmeier. It has been adapted for apply on the web.

Perennial vegetables are great soil builders

Perhaps the best ecological benefit of perennials is their beneficial effect on the soil. Bare soil dries out quickly and can be damaged by wind and rain, especially in sloping gardens. Tillage also kills many of the beneficial elements of the soil food web, particularly some of the best types of mycorrhizae (beneficial fungi that share nutrients with crops). Well-mulched perennials require no tillage at all once they are established.

But the soil benefits of perennials are not just due to the lack of tillage. Perennials improves the content of organic matter, soil structure and porosity, and water capacity through the leisurely and steady decomposition of roots and leaves. Perennial vegetable gardens build soil the way nature intended—by allowing plants to add more and more organic matter without tilling, and letting worms do the work of mixing it all together.

Perennials provide ecosystem benefits

Perennials, especially trees, leisurely global warming by capturing atmospheric carbon dioxide. Trees also moderate microclimates, making the areas around them cooler and wetter. Vast numbers of trees can similarly moderate the climate of entire regions. The root systems of perennials capture and store water and nutrients which would otherwise be washed away. Perennials provide necessary habitat for many animals, fungi and other life formsmany of which are very useful in gardens.

Perennial vegetables extend the harvest season

Perennials often have different availability times than annuals, which helps spread the harvest season out over a larger part of the year. By the time you start your seeds indoors and transplant the diminutive, tender seedlings into the garden (which needs habitual watering and weeding), perennials are already well into growth and ready to harvest. In my own garden, I start eating the first tender shoots of perennials shortly after the snow melts. Later, in the heat of midsummer, I visit the scorching balmy beds along my driveway to harvest some delicious tropical, warm-season greens. Perennial vegetables can “fill” times of the year when your annual garden doesn’t have much to offer.

Perennial vegetables can often perform multiple functions in the garden

In addition to years or decades of low-maintenance yields and soil-building benefits, perennial vegetables can perform other significant tasks in the garden. Many of them are lovely ornate plants, offering the potential for attractive edible landscapes. Some species can function as hedges, ground covers or erosion control on steep slopes. Some provide free fertilizer for themselves and their neighbors by fixing nitrogen or accumulating nutrients in the soil. And some assist in Pest controlproviding habitat or food for predatory and other beneficial insects. Vines such as chayote and perennial cucumber can be grown on trellises to create “edible shade houses” where you can snack in a frigid spot out of the sun.

Disadvantages of perennial vegetables

No crop is perfect, and perennials are no exception. Here are some of the disadvantages of growing perennials.

Some perennial vegetables take root slowly, and It may take several years before it starts producing good yieldsA classic example is asparagus.

Like annual crops, Some perennials become bitter after flowering. Therefore, their greens are only available early in the season. Perennials are not designed to replace annuals, but to supplement them. In this case, perennials are available early in the season, providing greenery until the annuals have sprouted and begun to grow.

Many of the smaller, perennial vegetables are rather forceful flavorsespecially those adapted to cool climates.

Many perennial vegetables require so little care that can become weeds in your garden or escape and get used to nature in your neighborhood.

Perennial vegetables also don’t fit into your regular annual garden management plan, and it will be necessary to allocate an area for them (like you probably do now with asparagus, artichokes, or rhubarb).

Perennials have special disease challenges. First, you can’t rotate crops to minimize disease. Second, when disease does occur, it’s often for good—for example, plant viruses are problematic in some vegetatively propagated perennials.

Note on “Perennials Grown as Annuals”

You may sometimes hear a crop referred to as a “perennial grown as an annual” (some of these plants are referred to here as “planted/transplanted perennials”). Sometimes there are good reasons to grow perennials as annuals. For example, if potatoes are left in the same place year after year, they will be subject to terrible diseases. On the other hand, many plants that are usually grown as annuals are good perennials (such as skirret, which has a better flavor when grown as a perennial).

In some cases, we simply do not know what would happen to these crops if they were allowed to survive for many years. Perhaps fresh techniques would have to be developed to manage them in this way. I hope that the readers of Perennial Vegetables know what will happen.

Why you’ve probably never heard of them

Why are asparagus, rhubarb, and artichokes the only perennials most gardeners have heard of? I have some practical answers and some speculative ones, which are discussed in a companion article.

Lack of information

When I first became interested in perennials, I found myself having to search here and there for bits and pieces of information. There was not a single book or website devoted to perennials. You can read many gardening books, flip through issues of gardening magazines, and never have any idea that this other class of vegetable even exists. I sincerely hope that the publication of this book will assist to rectify the situation.

The Chicken and Egg Problem

Only a miniature number of nurseries and seed companies offer even the best perennials—some are still unavailable for sale in the U.S. and Canada as I write this. These plants will never have a chance to become popular if no one can buy them. On the other hand, nurseries and seed companies will never offer them if there is no demand.

Perennial Vegetables readers can assist break us out of this cycle by asking (or rather demanding!) for perennial vegetables from their favorite companies. With your assist, these useful and delicious plants will soon become widely known and cultivated.

The Beginnings of Annual Farming in North America

In the United States and Canada most of our gardening traditions come from Europe, where there are few perennial plants (except for fruits and nuts.) But most of our land mass is well-adapted to crops from hot and tropical regions—where, as it turns out, there are many perennial vegetables.

But why haven’t people grown perennial vegetables in the United States and Canada for centuries? There are many more perennial vegetables in the tropics. Why have so few perennials been domesticated in cooler, more temperate climates? The answer may have its roots in the many independent origins of agriculture itself and the historical peculiarities of the areas where crops were domesticated.

In tropical regions of Africa, Asia, and Latin America, agriculture developed heavily around root and starchy fruit crops as the primary crops. This allowed for the cultivation of a mixture of trees, vines, perennials, and annuals. Nippy and temperate Eurasian agriculture relied on annual cereals and legumes. Why was this? Partly it is a matter of the plants available as raw materials for domestication—perhaps, with a much greater variety to choose from, there were more candidates for perennials in the tropics.

But, interestingly, Europeans actually took some perennial wild edibles and grew them into annuals, such as beets and brassicas. And the archaic Andean people domesticated perennial, not annual, forms of arracacha. In fact, a striking number of perennial vegetables are native to tropical America, such as chayote, chaya, and perennial beans.

One possible explanation is that in the Americas there were no domesticated draft animals to pull plows. All agricultural work had to be done with hand tools, allowing different parts of the farm to be treated individually without additional energy costs. In most of the Ancient World, draft animals were used to plow enormous areas. Growing perennial crops would have required areas devoted to different management systems. Perhaps this explains the “annuality” of wild perennial crops such as beets and brassicas.

Jared Diamond’s Guns, Germs, and Steel offers an intriguing history of agriculture. It turns out that agriculture in Eurasia began in the Mediterranean basin, in a rainy-summer climate favorable to annual crops. These crops were adopted in Europe and may have replaced the development of perennial crops that might have otherwise occurred.

Another factor may be that the primary concern of early plant breeders was to obtain sufficient food. Perhaps the raw material from annuals provided faster rewards than perennials, especially in cool climates where the low season often requires several years for perennials to begin bearing fruit.

Whatever the source of our neglect, there is certainly no longer a good reason to ignore these useful and productive crops. They can be made much more widely available, and I believe that the network of gardeners will prove to be an significant fresh element of food production in the United States and Canada in the years to come.

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