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What are annual and biennial plants?
Annual plants are plants that grow, flower, produce seeds and die in a single growing season.
Biennial plants complete this life cycle in two seasons: most biennials are sown in late spring or summer. They establish during the first year, growing leaves and developing the root system. Then, in the next season, they bloom, produce seeds and die.
There are also plants that, as they are not rustic, are used as annuals. Some of these plants are actually perennials or even shrubs but are cultivated for just one year.
How to grow annuals and biennials
Annual and biennial plants can be grown from seed, purchased as young seedlings, or purchased as mature specimens ready to plant and create immediate effect.
The most economical option is to grow them from seed. Especially if you have a big garden or lots of pots to plant.
Due to the nature of their life cycle, the way to propagate these plants is from seeds.
Thus, most annual and biennial seeds are very easy to germinate. They rarely go dormant, as happens with plants with longer life cycles, and therefore do not need special treatment before sowing.
They germinate easily and quickly, providing a display of color in a short time – some annual flowers bloom in a few weeks.
The germination of most annual plants is really very simple. It can be made in trays or pots in a greenhouse, in a cold frame or even outdoors in the definitive place.
What determines the most appropriate place for sowing is the rusticity of the plants (tolerance to frost) but also the local climate and its tolerance to transplanting.
If you purchase small plants, often sold bare-rooted, plant immediately and water well. Pay attention if the danger of frost has passed. If there is still a risk, you can plant the seedlings in small pots and protect them from frost before planting in the final location.
Tip: When sowing in the ground, sow in straight lines or with some pattern. This way, it will be easy to distinguish them when pulling out weeds that may also germinate.
When to sow annual flowers?
The sowing of annuals to flower in summer and autumn is done in late winter and spring. The sowing of plants that bloom in winter and spring, such as pansies, is done in summer.
When to sow biennial flowers?
Biennials must be sown in summer. Sow seeds in a corner of the garden, as they will have to grow during the first few months without developing much visual interest.
When they are well developed, in autumn, they are transplanted to the definitive place where they will bloom the following spring.
Buying seeds
Annual and biennial flower seeds are readily available at garden centers or even supermarkets. If you are looking for a more specific variety, you may have to look online.
Mark the beginning of the sowing season on the calendar (late winter/early spring for most plants) and list the flowers you want to grow.
Seeds are usually packaged in protective aluminum packets and sealed to keep them fresh and viable.
When the package is opened, the seeds deteriorate more quickly. So just open it when you are going to sow. However, if the package is tightly sealed with tape and kept in a cool, dry place, most annual and biennial seeds remain viable for more than a year.
Check that the package is in good condition and confirm the date to make sure the seeds are fresh.
How to harvest seeds
Seeds should be taken from vigorous, healthy specimens with good flowers. This will give more assurance about the characteristics of the next generation plants.
Collect the seeds as soon as they start to change from green to ripe colors, typically in shades of brown or black.
You have to be careful to pick them at the right time and prevent them from opening up and spreading.
It is best done in a dry day. Collect the seeds individually or the stems themselves into paper bags or boxes and place them in a dry and ventilated place. Don’t forget to label the plant names so you know what’s in each bag or box.
If the seeds do not release when dry, gently break the capsules to release them.
Once separated and dried, the seeds can be stored in packages or envelopes in a cool, dark and dry place. You can put them in airtight bags or jars in a domestic refrigerator until sowing time comes.
List of annual and biennial flowers
See our list of annual and biennial flowers here. It is still growing.
