In my experience with growing food in Ontario, food-producing perennials have been precious and always too rare. Every time I’ve gotten the chance to try growing a new one (even if I had no idea how to cook it), I’ve jumped in with both feet. By the end of this post, I predict you’ll do the same. 

So what is a perennial crop? It is a plant that can be cultivated as a food source and that lives for more than two or three years. In a climate with harsh weather, a perennial’s stems and leaves may die back seasonally, but they regrow each year from the same root system. Perennial plants are differentiated from biennials, which die after going to seed in their second year, and from annuals, which complete their whole life cycle in just one year. 

Climate can affect whether a plant is perennial in a certain area: tender plants that thrive year-round in Mexico will often perish in a northern winter. That’s why the ones that do survive in temperate zones are so valuable. And it isn’t only a question of scarcity, or of their ability to save you time and effort. Plants that can keep their living roots in the ground year after year are also a powerful resource for creating and maintaining rich, healthy soil and even sequestering carbon. 

Types of Perennial Crops for Cold Climates

• Leaves
  • Sorrel
  • Fiddleheads
  • Chives
  • Most cooking herbs
  • Onions
  • Garlic
  • Kale
• Shoots
  • Asparagus
  • Hostas
• Stems
  • Rhubarb
• Tubers
  • Jerusalem Artichokes
  • Potatoes
• Taproots
  • Dandelions
  • Horseradish
• Fruit and nut trees

Orchards offer the most obvious and widespread example of perennial crops. Trees and shrubs, with their tough, woody stems and trunks, have adapted to nearly every climate in the world. As a result, nuts and fruits are familiar to everyone. 

It is harder for most westerners to name perennial vegetables since the short list of plants cultivated for our grocery store shelves don’t fall into this category. The number of perennials available also varies from region to region, since many are too tender to survive freezing temperatures. Still, they do exist, and you should recognize many of them. The list below is sorted by the part of the plant that we primarily eat.

Leaves

Shoots

Stems

Tubers

Taproots

• Horseradish (do some research before growing this as a perennial since it requires some specialized techniques to access the young, tender roots that are desirable for eating)^[1]
• Dandelions (these can actually feature on nearly all of these lists since every part of the plant is edible, depending on the time of year.)

For more details on some of these crops and notes from my own experience growing them, check out this post.

How can I discover more perennial crops?

In many climates, the list of perennial options for vegetables and grains is woefully short. How can we grow more perennials in the future? By looking to the past. Before our diet shrank to a handful of fruits and vegetables that are easy to transport long distances to grocery stores, people ate a much wider variety of plants. Some that survive in our flower gardens include hosta shoots, goutweed leaves, and most parts of the daylily. Other edibles have become weeds we fight against, like Japanese Knotweed and of course the infamous dandelion^[3]. Still more are native plants like cattails that most of us vaguely know have traditional uses, but the knowledge is not widespread. 

I have been obsessed with identifying edible plants since my early teens, yet I am still constantly astonished to discover new ones that I thought were only ornamental or only a roadside weed. With a little research and an adventurous approach to meals, perennial crops are everywhere—and they will be there year after year after year.

Pros and cons of growing perennial crops.

Big-picture ecological impacts are exciting and necessary to understand, but naturally there are other considerations that growers need to take into account, particularly if they intend to produce more than a family-scale harvest. Here are some other factors to keep in mind. 

Positives

• Perennial plants have deeper roots than annuals. This gives them greater drought resistance since they can reach down to deeper reserves of water.
• Deep roots also give perennials more stamina against the wind, since they are better anchored in the soil than shallow-rooted annuals are.
• Perennials can maintain and add fertility in their soil without fertilizers and amendments. In annual growing systems, the soil’s humus is turned into plants that are then entirely removed, so fertility is reduced with each harvest. If the soil is left bare between crops, the effect is worsened by sun and wind damage.^[2]
• Your labour is decreased since you don’t have to replant your crop once or even several times a year. 
• Cost is also reduced over the long term since you are not putting resources into purchasing new seed and preparing the soil.
• For commercial growers with access to a niche market, unusual perennial crops can command a high value. 

Negatives

• While annuals are harvested the year they are planted—some after just a matter of weeks—most perennials take much longer to get established. In some cases, like fruit trees, a reliable harvest is a decade away.
• The upfront costs can be much higher since growing perennials from seed is often difficult. As a result, growers must budget extra money to buy, for example, vegetable transplants, fruit tree saplings or whips, asparagus crowns, or sunchokes tubers. 
• For commercial growers, scalability can be a challenge. The most cost-effective crops for many commercial operations are the ones that can be harvested mechanically. Harvesting certain perennials on a large scale may need to be done by hand, by individuals with some degree of specialized training. 
• Unlike crops like lettuce, which can be planted and harvested several times in a season, or rotated with other crops, perennials take up space permanently but may only produce a harvest once a year, depending on the part of the plant that is used. Leaf crops like herbs and sorrel are exceptions.

Ecological benefits of perennial crops

From a fertility perspective, bare soil is a wound that nature wants to staunch. Exposed earth loses carbon to sun damage and washes away in the rain. In these situations, nature uses quick-growing annuals (weeds, from a human point of view) as a band-aid to stop the bleeding. For the long game, however, perennials are king. 

The permanent presence of perennial roots in the ground forms the infrastructure around which soil ecosystems thrive. The plants turn sunlight and carbon into sugar, and the soil organisms turn the sugar into humus—a stable form of carbon that can last for thousands of years, even through fire and drought. This humus and the tunnels of the soil-dwellers also create a porous soil that captures and holds rainwater. This mitigates flooding, raises the levels of water tables, and improves drought resistance. 

Citations

1. Bratsch, Anthony. “Specialty Crop Profile: Horseradish.” VCE Publications 438-104
   pubs.ext.vt.edu/438/438-104/438-104.html
2. Ecological Society of America. “Sustainable Agriculture: Perennial Plants Produce More; Landscape Diversity Creates Habitat For Pest Enemies.” ScienceDaily. ScienceDaily, 6 August 2009.
   sciencedaily.com/releases/2009/08/090804071358.htm
3. Zachos, Ellen. Backyard Foraging: 65 Familiar Plants You Didn’t Know You Could Eat. North Adams: Storey Publishing, 2013.