What are Annuals Plants
Annual plants are plants which complete their life cycle within a single growing season – grow, flower, produce seeds and die. There are two distinct groups – hardy annuals and half-hardy annuals. Hardy annuals can withstand some frost, and can be sown directly in the open where they are to flower. Half-hardy annuals on the other hand are not frost hardy and are normally sown in a temperature regulated greenhouse and only transplanted outside once the risk of frost are over.
These seedlings are normally raised in huge quantities every year in nurseries for sale as bedding plants and are used widely for summer display. They can be raise from seed sown between January and March in a heated greenhouse. Sowing is usually carried out in trays or boxes with pricking of the seedlings as soon as they can be handled.
As the plants developed they require more ventilation and the trays are then transferred to a cold frame if one is available. The plants have to undergo the hardening-off process before they are being planted out. Only plant out half-hardy annuals after the risk of frost is over. Examples of half-hardy annuals are zinnia, petunia and lobelia.
In warmer and mild areas autumn sowing of hardy annuals are feasible and may results in earlier and better flowering than those sown in spring. In cold areas autumn sowing will not be successful as the cold winter may kill the young seedlings. Therefore it is better and safer to sow in spring.
Annuals that can be sown in autumn and have a better chance of survival
- Cornflower (Centaurea cyanus)
- Candytuft (Iberis)
- Larkspur (Delphinium ajacis)
- Love-in-a-mist (Nigella damascena)
- Marigold (Calendula officinalis)
Annuals that are best sown in spring
- Clarkia elegans
- Godetia grandiflora
- Gypsophila elegans
- Centaurea moschata (Sweet Sultan)
For a fruitful planting the soil condition must be good. For spring sowing, the soil should be turned over in the autumn and left exposed to the winter weather. To enrich and fertilize the soil the use of fertilizers is necessary; mixing superphosphate into the soil before sowing will benefit the seedlings growth. The addition of garden compost, leaf mould and peat will help to lighten heavy soils. Before sowing the seeds the soil must be rake till it is fine and level. Hardy annuals are usually sown on beds solely for growing hardy annuals or around borders.
Divide the area for planting and mark and label each variety accordingly. With a rake or hoe, draw shallow drills within each area and sprinkle the seed thinly into these drills. Pull the soil over the seeds to cover them and press the soil down firmly with a presser. By sowing the seeds in drills help you to differentiate between weeds and flower seedlings easily; those growing in the dills and in rows are the flowering seeds.
When the leaves sprout through and spread over the soil they must be thinned to avoid overcrowding. When thinning, remove the weak seedlings and space out the good and strong seedlings of about 15-23 cm apart. Those sown in early autumn are thinned out either in late autumn or left until the early spring. While thinning, remove all weeds and preferably weeding should be done in the early stages.