Do words or phrases ever remind you of something completely non-related? Growing up, when we’d be on a road trip somewhere we’d invariably end up playing a version of 20 questions that we called “Animal, Vegetable, Mineral”. The reason we called it that is because that was the first question you’d ask: “Is it an animal? A vegetable? Or a mineral?” When I was writing the title to this post – Annual, Biennial, or Perennial – I was reminded of that game, because those are the first questions you should ask when a) deciding on a new plant for your garden or b) trying to remove an unwanted plant (i.e. a weed) from your garden.

Is it an annual, a biennial, or a perennial?

Knowing the answer to that question can help you decide what to bring home from the garden center and has the potential to save you from heartache later on. Looking for a plant that will grow quickly and fill in some empty places while you’re waiting for your shrubs to mature? Try planting some annuals; quick and colorful. Maybe you only want to dig a hole once (ha!) and enjoy flowers there year after year? Go for a perennial. Wondering why that beautiful flower you just loved last year didn’t come back this year? It very well could have been an annual. Tired of pulling the same weed over and over and over? It’s probably a biennial or perennial.

So let’s talk. What is it that makes a plant an annual, biennial, or perennial?

I really thought this graphic showed plant life cycles clearly and concisely. I found it at the CEPLAS: Cluster of Excellence on Plant Sciences website.

Annuals: these plants complete their life cycle in one growing season, and then don’t come back again the next year. (Their seed might, but the original plant won’t.) Horticulturally, some plants are treated as annuals in certain growing conditions. For example, cannas, those lovely tropical plants you might have growing in a container on your porch, are perennials in their native environments but don’t survive the cold winters where I live so they are treated as annuals – if you want them in your garden you have to buy new ones every year.

Biennials: these plants live for two years. Generally, during the first year, they exist as a rosette or vegetative form and in the second year they will flower. Have you ever left an onion or carrot in your garden over the winter and then the next spring it has flowers on it? Those are biennials. Some flowers, like forget-me-nots or some hollyhocks, may seem like a perennial on the surface – they keep on blooming year after year – but they are actually biennials or short-lived perennials that self-sow.

Perennials: these plants live for more than two years. Trees are obviously perennial, as are shrubs. But herbaceous plants can be perennials, too. Some perennials are simple; that is, they have a taproot. That taproot stores up surprising amounts of energy so that the plant can regenerate from that root year after year (or throughout the summer even though you keep pulling the top off – think of a dandelion). Other perennials are classed as creeping perennials; that is, in addition to reproducing sexually (through seed) they can also reproduce vegetatively through rhizomes, stolons, and/or bulbs, tubers, and corms. These are the plants where you can plant one and pretty soon it has filled in the entire bed (whether you wanted it to or not).

This garden, grown by a former college professor of mine, is made of all annual plants. It requires a lot of work to design, install, and maintain, but he gets to enjoy colorful blooms all summer long and a different design each year.

I’m curious. Which do you prefer? Annuals, biennials, or perennials?