Annuals and Biennials

Annuals are plants that grow and flower within a year, then die. Vegetables are grown as annuals, so are some flowers.

Some tender perennials are treated as annuals, and replaced each year. A tender plant is one that gets killed by frost, so it does not survive the winter. There are tender annuals as well. If you have a tender plant, then don't plant it out before the first frost. This is an important date, which you should work out for your own garden (normally by losing plants that you've planted out too early!) I consider the last frost to happen before the first week in May (the local elections!) I have known a frost later than this, but it's rare for my garden. Other gardens may have the last frost earlier or later.

Some perennials get very leggy after a year, so are treated as annuals and replaced.

Since an annual needs to grow within a year, the seeds must be sown early enough for it to grow and flower within the year. You can sow your own seeds. If the plants are tender, they may need to be sown in a pot, and kept on a window sill until planting out after the last front. Other seeds can be planted outside. They may be sown in their final position, or sown in a row, then transplanted as necessary.

Another way to grow annuals is to let someone else do the sowing for you, buy the small plant and plant it out. As long as you keep it watered, this is easier, and you're more likely to get the flower to survive! You can buy these annuals in garden centres or even supermarkets. They are called bedding plants, and they are sold in trays of half a dozen or more. This is because they are cheap, and not worth selling individually, but it is annoying if you just want a single plant!

A biennial is very like an annual, as it only flowers once, then dies. But it starts growing from seed in one year, and doesn't flower in that year. It has to survive the winter (so must be hardy) and is usually ever-green. Next spring, or even summer, it flowers, then dies.

So an annual is sown in the spring, flowers in the summer, then dies before winter. A biennial is sown in autumn (or perhaps summer), grows leaves but doesn't flower in the autumn, is dormant in the winter, then grows more leaves and flowers in the spring or summer. A biennial has a longer life span than an annual, usually, but a similar one, just off-set by some months.

If you have plants that seed themselves, then you may not even be sure whether a plant is an annual or biennial, or even a perennial. If you are not sure, once the plant seems to have died, cut the plant off at ground level leaving the root. If the root is dead, it will rot away and cause no trouble. If not, it will grow again next year. Otherwise,leave them to it. They know what they're doing better than you do!