The word "perennial" means a plant that lives year after year and that usually survives the winter months to grow again. This is in contrast to "annual", which refers to plants that only live for one growing season and usually die in winter. The most common vegetables are annuals, which means they need to be resown every year. However, there are some vegetables that behave like perennials in most climates and therefore do not need to be re-seeded every year. Read on for more information on perennial vegetables. For references to the climatic zones indicated in the text, consult the standard classification of the US Department of Agriculture for a comparison with the Italian climate zones.
Steps
Part 1 of 3: Identifying Perennial Vegetables
Step 1. Grow Jerusalem artichoke
Jerusalem artichoke is a gnarled tuber that is usually prepared like a potato.
- Jerusalem artichokes can be very invasive, so you may prefer to grow them in containers.
- They thrive in cooler climates and the best harvests are those made after the first frost each year.
Step 2. Consider growing artichokes
Artichokes are grown for their edible flowers and create a striking vision to any garden. They are available in perennial or annual varieties:
- You can harvest from an annual plant the first year, but a perennial won't produce an edible crop the first year. However, once the perennial variety starts producing, it will yield year after year in warmer climates (zone 7 or higher).
- Another advantage of the perennial variety is that it offers higher yields than the annual one when it finally blooms. These types of artichokes favor sunny places and regular watering.
Step 3. Think about planting wild artichokes
Wild artichokes are a beautiful silvery plant similar in appearance to artichoke or thistle.
- They grow easily from seeds, favor a sunny location and develop as large but attractive garden plants that provide an unusual vegetable dish in the winter months.
- You will need to whiten the stems before eating them. This is done by wrapping the plants in bundles, surrounded by straw, and then accumulating soil around the plant.
Step 4. Plant asparagus in areas with cold winters
Asparagus does well as a perennial vegetable in areas that have a cold winter.
- Although the flower beds need a few years to stabilize, once you have a thriving asparagus bed you can count on a regular spring harvest every year.
- For more information on the cultivation of asparagus, see specific articles on the subject.
Step 5. Grow horseradish in zones 3 to 9
Horseradish is a strong-flavored root that is only needed in small quantities to energize food. If you want to grow this root crop as a perennial, leave a few roots in the ground and they will develop again.
- Horseradish will grow best in climate zones 3 to 9, both in the sun and in partial shade. Grown as a perennial, be prepared to see it spread - so consider planting it in a deep container if you wish to limit its spread. For more information on the growth of horseradish, see specific articles on the subject.
- A "zone" refers to the minimum average temperatures in winter in a given geographic area. There are 11 zones in North America, each colder or warmer than the adjacent one by about 5 - 6 degrees Celsius. To find out what the conditions are for gardening in an area in the US, visit the National Gardening Association website.
Step 6. Consider growing rhubarb in areas with rich soils
Strictly speaking, rhubarb is a plant rather than a vegetable, but it is commonly treated as a kitchen product. It loves rich soil and adapts well to colder climates.
- A rhubarb plant will often be productive for over a decade, but will grow best when divided every 4 years or so.
- Rhubarb will benefit from a manure mulch before winter arrives. For more information on the growth of rhubarb, see specific articles on the subject.
Step 7. Think about planting sorrel
Sorrel is a herb with a light lemon flavor that goes well in fish sauces. In zone 5, or warmer ones, it will grow like a perennial. Unusual for a perennial, it is possible to harvest early after planting - often after about 2 months, making it a fairly early vegetable and leafy salad in early spring.
- The sorrel will still grow after harvest, but the leaves turn bitter after flowering, so try to pluck the flowers when they appear. It produces a vegetable and an early leafy salad in early spring.
- For more information on the cultivation of sorrel, see specific articles on the subject.
Step 8. Learn about plants that will behave like perennials in the right climate
These include tomatoes, sweet potatoes and peppers. In colder climates the same plants will behave like annuals.
- Some gardeners outside the tropics may be successful by getting these plants to behave like perennials by having them overwinter in heated greenhouses or designated protected areas.
- However, this requires a lot of additional support and in-depth knowledge of gardening that is beyond the scope of this article.
Part 2 of 3: Planting Perennial Vegetables
Step 1. Add nutrients to the soil before planting
Since perennials will take up space in the garden longer than annual crops, it is very important to properly prepare the soil for lasting nutrition. To do this, mix some organic matter such as mushroom compost or well-decomposed manure into the soil before planting.
Step 2. Apply fertilizer on a monthly basis throughout the growing season
It is important to feed perennial crops with fertilizer to ensure that the harvest continues year after year. An all-purpose generic fertilizer should be applied at least monthly during the growing season.
Step 3. Mulch larger perennials to conserve soil moisture and remove weeds
Larger perennials - such as artichoke - will also benefit from mulching. Apply about 7.5 - 10 cm of organic mulch (e.g. well-decomposed manure) to the base of the plant to conserve soil moisture and eliminate weeds. Mulch will also help protect the roots.
Step 4. Realize that you will not be able to collect anything in the first year
Perennial vegetables typically take longer to reach the harvest stage of the annual variety. In many cases, you won't be able to harvest anything in the first year, especially if the plants are started from seed.
Part 3 of 3: Grow Biennials and Self-Seed Vegetables
Step 1. Encourage the growth of self-sowing vegetables
There are some vegetables which, strictly speaking, cannot be considered perennial, but which can usually be included because they self-sow. These are usually annual plants that produce seeds that fall to the ground and develop on their own, without any human intervention.
- Some examples of self-sowing vegetables include eternal spinach, parsley, carrots, and cherry tomatoes.
- To promote self-seeding, avoid planting the parent vegetable in grow bags or tight containers, as this leaves very little soil for the seeds that fall.
Step 2. Grow biennial vegetables that provide two years of harvests
There are some useful vegetables that are not perennial but live longer than annuals. Biennials tend to provide two growing seasons and that often means two harvests.
- Examples of biennial vegetables are Swiss chard, beets, Brussels sprouts, cabbage, cauliflower, celery, endive, kale, kohlrabi, leeks, onions, parsley, parsnips, turnips, sauces, etc.
- Celery cut in cold areas can provide a spring and fall crop. Don't believe the people who say they cut celery and see it grow back from the stump - this doesn't work too well in practice.
Step 3. Be wary of "voluntary" potatoes
Once grown, it is often difficult to get rid of potatoes because it is very easy to overlook a few small tubers when harvesting. These tubers grow back the following season, producing potatoes known as 'volunteers'.
- This is generally to be frowned upon, as tubers can carry disease from one year to the next and the necessary spacing is not optimal for a good harvest. Therefore, it is better to discourage potatoes that are obtained from a split crop.
- If your potatoes return the following year without an invitation, it's best for them to land (pile more soil or manure around the base of the potato sprouts) to keep them from being exposed to light. This will mean that the potatoes you harvest don't have to be green (you shouldn't eat green potatoes).
