The Gardener's Guide to Perennial Vegetables for a Home Greenhouse

One of the best things about being a gardener is being able to reap what you sow. Vegetable plants in particular are some of the most reliable crops to grow in the garden. But, in many places, winters are just too cold and they can succumb to the frigid weather. Even perennial vegetables, which can persist through the winter, may fall victim to freezing temperatures or persistent frost. 

One way around this is by using a greenhouse! Greenhouses protect plants by guarding them against the elements outside, whether it’s the bone-chilling cold or leaf-burning sun. This way, plants are able to grow year-round in a climate-controlled environment, and often have a higher yield than they would otherwise. 

What Are Perennial Vegetables?

Many vegetables, like carrots and lettuce, are annual species that need to be planted each spring. Perennial vegetables, on the other hand, live multiple years and reward their caretakers with fresh produce year after year. The key to perennials is that they don’t have to be reseeded each year. Just plant it once, and wait! Perennial vegetables are often some of the easiest things to grow in the garden. 

Why Plant Perennials in a Greenhouse?

If perennial vegetables can survive through the winter, what’s the point of planting them in a greenhouse? It’s true that many perennials are able to survive through the extremes of winter and summer. But, a greenhouse isn’t only about keeping plants alive. The biggest advantage of a greenhouse is being able to control the environment inside. By being able to regulate the temperature, humidity, soil moisture, and light, as well as protect plants from pests or pathogens, greenhouses keep plants stress-free. If a plant doesn’t need to worry about producing chemicals for defense, or cooling itself off in extreme heat, it can focus entirely on flower and fruit production. 

The other advantage of a greenhouse is its ability to extend the growing season of plants. Perennial vegetables can survive in the outdoors, sure, but inside a greenhouse, their growing season can easily be greatly extended. A longer growing season means higher yield, as a vegetable plant can produce both earlier and later in the year. So, while all the outdoor vegetables are getting ready for winter, a perennial vegetable in a greenhouse will still be happily producing its crop. 

Perennial Vegetables to Grow in a Greenhouse

Not all perennial vegetables are suitable for a greenhouse. Although some plants would theoretically do better in a greenhouse, their growth form or sheer size wouldn’t be best for indoor life. For example, blackberries and raspberries grow fast and can be unruly, and their spiny stems would pose a risk to the plastic walls of a greenhouse. 

In addition, some sun-loving plants would rather be outside than in a greenhouse – at least during summer. In the winter, these plants would be thankful to be inside a greenhouse to protect them from the cold. 

Green Vegetables

Although many green vegetables are annuals, especially leafy greens, some are perennials. Even though they can be dormant in the winter, they will grow fast and furious in the spring and summer when in the comfort of a greenhouse. Here’s a shortlist of some perennial green vegetables that will do well in a greenhouse

• Asparagus  – When grown in a garden bed, asparagus can produce stems for up to 20 years!

• Artichoke – As herbaceous perennials, artichokes live more than a year but are typically short-lived (1 or 2 years). They will do well in a greenhouse and can grow to be 2 meters (6 feet) tall, so it needs space!

• Chives – Chives are vigorous growers and will provide abundant stems for you to enjoy. They are also one of the best vegetables to eat fresh.

• Rhubarb – Rhubarb needs at least a year to become established. Resist the temptation to harvest its stems in the first year, and rhubarb can grow to be 20 years old!

• Spinach  – Not all spinach varieties are perennial. Try some exotic varieties like Ceylon, Sissoo, or New Zealand spinach.

Roots and Bulbs

Lots of vegetables produce their edible parts underground in the form of tubers or bulbs, which are specialized roots. Many of these can be sustainably harvested and grow as perennials in the garden, in or out of a greenhouse. 

• Garlic – Although garlic is normally grown as an annual, it’s also possible to treat it as a perennial. Once planted, forget about it for a couple of years. Then, bulbs can be harvested from the plant while still leaving enough in the ground to produce more for future harvests. Garlic works especially well as a perennial in a greenhouse, where its dormancy period is shortened and sustainable harvesting can happen sooner.
• Ginger – Ginger is a tropical plant, so it can’t survive temperatures colder than 50 degrees F even in a greenhouse. But, that just means greenhouses are perfect places to grow ginger in cooler climates where temperatures won’t drop too far.
• Sweet Potato – Sweet potato grows as a vine, and like ginger, can’t survive cold temperatures. In order to harvest the plant, you must actually remove the whole root from the soil, which kills the vine. Waiting a couple of years for it to become established allows you to harvest only some of the root, leaving the rest to continue growing.

Herbs

Many herbs are perennial plants that love to grow in pots. In addition, they can thrive in the dappled light of a greenhouse. Here’s a few easy-to-grow herbs that will thrive in a greenhouse.

• Lemon Balm – Lemon balm doesn’t like high humidity, so keep the soil somewhat dry. It also changes taste when it flowers, so nip those flower buds as soon as you see them.
• Mint – This is one of the easiest herbs to grow, and also one of the hardiest. It will do especially well in a greenhouse, but try growing it in a pot so it doesn’t take over a garden bed.
• Oregano – This aromatic herb will regrow vigorously when picked. It’s also easy to grow and will thrive in a greenhouse setting
• Parsley – Parsley is a biennial, but in a greenhouse, you can extend its growing period and take advantage of its fragrant leaves for longer than you would be able to otherwise.

Seasonal Greenhouse Perennial Vegetables

Many perennial vegetables are suitable for greenhouses, but only during the winter months. These are plants that you can grow in pots and move around freely in order to give them the best conditions. Bell peppers and chili peppers are perfect examples of seasonal greenhouse residents. When grown in pots, put them in full sun so they get their preferred amount of light. These plants don’t do very well in the cold, however, so they are often brought inside during winter. Instead of taking them indoors, put them in a greenhouse! The controlled climate in a greenhouse will protect peppers from cold winters until it’s warm enough for them to go outside again.

Conclusion

Perennial vegetables are perfect plants to grow in a greenhouse. Home greenhouses are possible to make even with little space or to buy with a tight budget. If you do take advantage of a greenhouse, you’ll be rewarded with higher yields and an extended growing season for your vegetables. If you already have some perennials in an outdoor garden bed, you can even build a makeshift greenhouse directly on top of the bed to protect your plants from cold winters. 

Hopefully, now you have an idea of the benefits of growing perennial vegetables in a home greenhouse. In addition, you have some ideas of which vegetables can last for years in a greenhouse!

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