Annual versus perennial — caring, planning for temperature sensitivity

An annual is a plant that starts from a seed, matures to bloom, produces seeds and finally dies — all in one growing season. A perennial is a plant that starts from a seed and may mature, bloom and produce seeds in the first growing season, or it may take several years before it is mature enough to bloom. During the dormant, nongrowing season, the perennial will typically die back to the roots or possibly a swollen trunk and roots that survive until the next growing season. The annual will always be restarting from seeds, but the perennial can start the second season from roots, bulbs, tubers or other storage systems.

Trees, shrubs, vines and other plants that have woody above-ground parts and survive the dormant season are not considered perennials.

If an annual is grown in an indoor location or in the Deep South where no frost occurs, it could keep growing for several seasons, possibly for a couple of years. It would be fooled into thinking that the dormant season has not yet arrived and would continue blooming.

As for perennials, you’ll need to research the regional climate in which the plant is native. If you have a perennial that is used to going dormant because of cold winter weather, it will behave the same in your climate. Planting a cold winter dormancy plant in Southern California, or in the southern states will not give it the cold weather it needs. These plants depend on certain amounts of cold weather to cause the maturing of their flower buds. Without enough cold weather, they don’t grow well. For instance, people who want to grow tulips in Texas need to buy ones that have been refrigerated, so that the cold temperatures have matured the flower into blooming.

Some perennials come from a warm weather climate that causes dormancy from dry spells. Growing them in the southern United States or indoors will give them the conditions they need. Planting one of these plants in cold winter weather will most likely lead to its death.

Many of the plants that are sold in the spring for use as annuals are actually warm climate perennials. They will act as an annual in cold weather climates, since they can’t tolerate the cold weather. Walk into any garden center or big box store in the southern states during the spring, and you will find numerous plants being sold as landscape plants that can be sold by the same chains in the northern states only as house plants or as an annual.

Another thing you must consider when looking up these plants in the books is that many plant groups have some annuals, some perennials and maybe even some shrubs or vines all grouped together in a common genus. The book may be talking about one particular species, or it may be discussing the majority of the genus when listing a plant as an annual or perennial.

If you have a warm-weather perennial and you don’t want to treat it as an annual, you will need to try to mimic its native climate conditions. Before the weather gets too cold, you will need to bring it indoors. You should bring it in when the temperatures are about equal indoors and out. In other words, when the air conditioning and furnace are both not needed. Don’t wait until the day before the first killing frost to bring them in; they have already been out in too many cool nights.

Cut back on the watering and let the plant drift into the natural dry season conditions that it is supposed to be receiving during the dormant season. Keep an eye on the plants as they may need a little water to keep them alive. Replant them outdoors next spring after the weather has become warm again.

Many plants are used as annuals or as houseplants that are actually longer lived plants. You may be familiar with the Christmas poinsettia and the Easter lily. The poinsettia is usually thrown away after being used for just a few weeks; however, it is actually a shrub native to Mexico that will last for years if planted in a frost-free area. The Easter lily is a bulb that will bloom in your northern yard for several years, but it will bloom in the summer and not at Easter time.