An annual is a plant that goes through its life cycle in one year or less. So each year, you need to plant your annuals anew, as opposed to perennials, which can live for additional years under the right conditions.
How good a time of year it is to buy and grow annuals depends on where that time is relative to their growing season, how able you are to get the better plants available at that time, and whether prices tend to be high or low at that time. Use the following pointers as a guide to when to buy annuals:
1. Most annuals are best planted in the spring, after the last frost.
You'll want to research the specific type of plant you're considering to be sure, but with most annuals, as soon as it starts to get warm in the spring, they should do well. Plant them too early, and a frost could doom them.
Prices probably won't be great this time of year, since demand will be fairly high. If price is only a minor consideration, go ahead and get them at the beginning of their growing season in the spring. If price matters more to you, consider delaying.
2. Prices are often highest on Memorial Day weekend.
Either don't delay at all, or delay until after Memorial Day, because prices tend to get even worse that weekend. It's a time when many people's thoughts turn to summer activities like gardening. Even if they've been ultra cautious about a late frost, they're probably confident enough by Memorial Day. Plus it's a holiday weekend, so they have time to devote to starting or working on their garden. Therefore, merchants know that demand will be higher than ever, so they set their prices accordingly.
3. Prices often drop right after Memorial Day.
Merchants stock heavily for Memorial Day, and whatever they don't sell that weekend they want to get rid of fairly quickly, so prices typically drop, sometimes a lot. So consider shopping during the week after Memorial Day. It's still fairly early in the season, yet the prices will probably be better than any earlier time.
4. The longer it gets into the season, the more careful you have to be.
Once you get into summer, then midsummer, then late summer, there's a gradually increasing chance the plants for sale won't be in quite as good shape, plus you won't be able to enjoy them as long before the growing season ends. On the other hand, you should be able to find some very good deals the later it gets. So as long as you're picky and you examine carefully what you're buying, later in the season can still be a good time to buy annuals.
5. Get to know your store.
It isn't just the time of year that you want to consider when deciding when to buy annuals. If you familiarize yourself with the stores in your area that sell plants, you can find out when their shipments arrive, so you'll know when to be at the store if you want first crack at the fresh arrivals. By getting to know the employees you can also get some other good tips and advice. For instance, there may be plants they're trying to get rid of after a storm that don't look so good, but in fact can easily be nursed back to health with a little aspirin water, that they'll let you have cheap if not free.
6. Look for annuals just short of full bloom.
All else being equal, you're best off with annuals that are about to bloom rather than those that are already in full bloom. The latter look more impressive in the store, but you'll get more out of the former once you transplant them into your garden.