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What are Annuals and Biennials?
 By
Michael Russell
True annuals are plants that will complete their life cycle within twelve
months of sowing. Biennials require two growing seasons to do so and are usually
sown in summer to flower during the following spring and summer.
Many other plants that botanists would define as perennial can be treated as
annuals, although some are half-hardy and, while able to flower well for a
single season, are not hardy enough to be used for more than one year.
Half-hardy annuals are generally raised in a greenhouse, then 'pricked out'
(transplanted, a few centimeters apart in larger boxes) and grown under
protection before being planted out.
The winter hardiness of biennials depends on the district where they are to
be grown. But there are significant advantages in planting out in late summer or
autumn for all those hardy enough to winter well. For example Canterbury Bells
that are planted outside as transplants in the autumn will flower well the
following summer, but if planted out in the spring they tend not to flower until
twelve months later!! Sweet Williams behave in a similar way.
Biennials are usually sown in a seedbed in the open, or in boxes in a frame
or greenhouse, and transplanted as seedlings. They are then put in their final
quarters in late autumn, as in the case of Wallflowers which do best in cool
regions. It is quite important to plant out forget-me-nots and cinerarias in the
autumn, as both of these flower early and therefore need to be planted out well
ahead of flowering time.
Cinerarias are suitable only for areas free from frost but in such areas they
are very showy and they are particularly useful for shady gardens. There are
short, medium and tall types and the color range is wide. Especially good are
the rich blue shades.
Plants that are not frost hardy include Begonia semperflorens, coleus and
impatiens. The latter have become extremely popular plants. They are available
in both short and taller varieties and also in numerous double flowered
cultivars, which are mainly propagated by cuttings. Impatiens grow well in full
sun if watered or in shade and are popular container plants for patios.
Hardy biennials are plants that are sown the year before they are expected to
flower. They are raised in a seedbed outdoors or in a cool, shady frame and may
be thinned out or transplanted when large enough. For best results planting out
should be done in the autumn. If they are bought from the garden center in
punnets or seedling trays, plant them out early in the season. Even in areas
where the winters are mild, planting at that colder time will result in small
flowering plants, except perhaps with pansies and violas.
Annuals that can be sown directly in well prepared flowerbeds and which come
quickly into flower are bound to be popular if they are capable of sustaining
flowering for a lengthy period of time. There are numerous suitable varieties to
choose from and in most cases they may be sown in boxes and transplanted. Before
sowing time, prepare the growing site. If the soil is lumpy and heavy, compost
should be worked in and planting mix applied to the surface. Then choose a dry
day, apply a little general fertilizer and rake it in. Seed can be broadcast or
it can be sown in shallow drills.
Some seedlings can be safely transplanted but the following do not transplant
easily: clarkia, eschscholzia, godetia, gypsophila, linaria, nigella and
poppies.
Half hardy annuals must be raised in a frame or greenhouse or in a few cases
sown outside after the danger of frost has passed.
Germination time varies, and most kinds require pricking out into boxes or
pots of potting compost. Some of the seeds such as lobelia, begonias and
petunias are very small and need to be sown carefully and kept out of direct
sunlight.
Nowadays the numerous garden centers often do all this work for you offering
a good range of these plants n punnets ready for planting. But it may be that
you want to use seed collected from your own garden, or wish to grown varieties
unavailable in punnets. In any case you will find that raising your own
seedlings can add a great deal of interest to your garden.
Michael Russell
Your Independent guide to
Gardening
Article Source:
http://EzineArticles.com/?expert=Michael_Russell
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