A Quick Guide to Annuals, Perennials, and Biennials For Your Home Garden

Annuals- biennials, perennials - you’ve heard all the words, but what does it mean, and why does it matter for your garden? Knowing how long you can expect your plants to live in your climate is key to know when making your planting plan, and can help you plan your garden for years to come.

An Overview:

Annual plants live for a single season, biennials produce seeds during their second summer, and perennials are the plants that for better or worse, come back in your garden year after year - and not because the seeds from the tomatoes that rotted on the vine last season are now sprouting where they fell - but rather, perennial plants go dormant in the winter and wake up in the spring.

It’s important to note that whether a plant is classified as an annual or perennial is largely dependent on its climate. Some warm weather crops may live as perennials when grown in warmer climates, but can’t survive harsh winters and so in colder climates they’re grown as annuals. We often think of tomatoes and peppers as annual plants that only live a single year, but they are actually perennial when grown in their native, warmer climate.

What are Annuals?

Annuals are plants that experience their entire life cycle in a single garden season (less than one year). For example, zucchini, winter and summer squash, melons, cucumbers, and okra are all examples of annual crops when grown in cold climates. They start from seed in the late winter or early spring, and then produce fruit during that single season, which contains their seeds. There are also herbs that are annual plants, including basil, cilantro, and chamomile. These herbs produce seeds every year - in fact, you might spend most of the summer months deadheading (removing the seed heads) these plants so that you can keep harvesting from them throughout the season. Once annuals produce mature seeds, the plant dies.

There are three primary types of annuals: tender annuals, hardy annuals, and half-hardy annuals. Tender annuals grow best in the warmer months are have little ability to withstand freezing temperatures. Half-hardy annuals can make it through some cold temperatures, but are not likely to survive a hard frost. Hardy annuals will still only live a single season, but they can withstand colder temperatures. Brassicas like broccoli and cabbage are hardy annuals - they actually grow best in cooler (but not freezing) temperatures. In four-season climates, these types of plants grow best during the spring and summer months.

What are Perennials?

Perennials are plants that live from year to year and produce edible food each year. Most perennials won’t produce food the first year that you grow them. Fruit trees are all perennials - that includes apples, pears, and different kinds of citrus and stone fruit. Other perennial crops that you can grow in your garden include asparagus, horseradish, and sunchokes (also known as Jerusalem artichokes). Prickly pear is another perennial plant that produces edible fruit (the cactus pads - also known as nopales) are also edible! Many herbs are also perennial, and will survive from year to year. Rosemary, oregano, sage, thyme, lavender, and chives are all perennial herbs that will grow back in your garden year after year.

What are Biennials?

Biennial crops get the least amount of attention, but there are quite a few biennial crops that are a staple in home gardens. Biennials are unlike both annuals and perennials in that they take two full growing seasons to complete their life cycle. That is, biennial crops start as seeds in spring and late winter, grow all season (and some you can harvest from throughout that first season!), live through the winter, and then produce seeds the next growing season. Kale is a biennial crop that is often grown as an annual. You can harvest leaves from a kale plant all season and then leave it to over winter if you want to save seeds from the plant the following year. However, many gardeners choose not to overwinter their kale. Depending on the variety and your climate, it can be difficult to keep kale alive through the winter - but I’ve been gifted seeds from kale that was overwintered in zone 4b before, so it’s definitely possible. Carrots are another type of biennial that are often grown as an annual. In order for the carrots to go to seed, you’ll need to either leave them in the ground the entire winter, or harvest the greens and roots intact and overwinter them in a sand or sawdust substrate to keep them healthy for planting next spring (storing garden carrots in sand or sawdust can keep them fresh for eating all winter, too!).

Garden Planning:
Now that you know the difference between annual, perennial, and biennial crops, you can take that information into account when planning your garden each year. While it is possible to move perennial crops, it’s best to plant them in an area where you’re going to want them to come back year after year. If you’re planning to save seeds from your garden (whether to share with other gardeners you know or donate them to a free community seed library), it’s important to know whether the plant you want to save from is a biennial or not (you can save seeds from annuals every year, and perennials most years) so that you can protect the plant through the winter. It’s also important to know if you have annuals, perennials, or biennials for companion planting purposes. Some crops grow better next to each other than others, and some plants are hostile to certain plants and make it difficult for them to grow. For perennials in particular, you want to be sure to plant crops that will live for years near other crops that will benefit their growth.