Gerberas are tender herbaceous plants native to South Africa and members of the Daisy family. The plants produce numerous long stalked daisy like blooms in a variety of colors. They are best suited as potted plants or annuals in cooler climates, but in the south and southwest, they may be grown outdoors as perennials. Grows well  indoors for early color. 

Sowing: Sow indoors at any time, from January to December

Sow indoors using pots or trays containing a sandy seed starter mix such as John Innes seed compost with added sharp sand. Sow thinly on the surface of the compost and gently firm down. The seeds require light during germination, so do not need to be covered. Some growers use a light cover of coarse vermiculite to maintain a higher humidity around the seed.

Place the pots or trays in a propagator or on near a bright windowsill that receives indirect sunlight. They need to be kept quite warm, the optimal temperature for germination is around 23 to 25°C (73 to 75°F), avoid temperatures above 25°C (75°F). Keep the soil damp but it is important that it is not too wet. Germination usually takes two to three weeks.

When large enough to handle, and roots start to be seen at the base, transplant the seedlings into individual 9cm (3in) pots to grow on. When the seedlings have four true leaves transplant to their final planting position into larger containers or into a greenhouse border. Transplant on time so that plants do not become root-bound. Plant with a spacing of around 30cm (12in) apart.

When planting, it is critical that they not be planted too deep. set the crown of the plant slightly above the soil level so that soil does not wash into the crowns. Rot will occur if the crowns are buried or the drainage is poor.

Water very carefully until established as young plants are particularly susceptible to overwatering, allow the surface of the compost to dry between each watering. Try to water in the morning to avoid water sitting on the growing tips as plants go into the evening period. Good air circulation is also important during this time.

Position:

Gerbera are winter-hardy to -2°C (28°F) although they are perennial in warm climates, they are fast growing and can be grown as an annual in cooler climates. They can be grown on a sunny windowsill in the house or planted in containers and moved to a cool greenhouse to overwinter. The plants need well-ventilated conditions with good light. A temperature of 10 to 20°C (50 to 68°F) in the growing season is ideal.

The plants are deep-rooting and don't transplant well once established, so are best grown in large containers or in a deep bed, in a greenhouse or conservatory border. To overwinter the plants indoors, plant them in pots and sink the pots in the soil, removing the pots when the weather turns cooler.

Given a minimum winter night temperature of not below 10°C (50°F), gerbera will flower all year round. In greenhouses at a minimum temperature of 5°C (41°F) they may flower in summer only, from May to October. As perennials, flowering is moderate in the first year following planting, then freely in subsequent years.

Cultivation:

Gerbera will thrive in rich gritty and well-drained compost. In containers use a John Innes No 2 potting compost with some extra grit or peat-free multipurpose compost. To grow in a greenhouse border, work in some extra grit and organic matter (peat, coir, leaf mould or well-rotted manure). Crown rot is a common problem, which is caused by planting the crowns too deeply. The crown should be visible above the soil.

Flowers can be produced within four to six months of sowing but young seed-raised plants will usually only flower lightly in their first season. These early flowers can be removed to help build up a vigorous crown. Once established, continue to remove flowers for cut-flower arrangements to provide more energy for new flower bud development rather than flower maintenance.

During the summer months, when the plants are in vigorous growth water them freely keeping them consistently moist and apply a general purpose liquid feed, such as tomato fertiliser at two week intervals to promote flowering. Provide a little shade from the hottest sun. Clean up plants by regularly removing diseased leaves and spent flower stalks. Slugs and snails are partial to the leaves so use methods to prevent these in your garden.

Overwintering:

In autumn, move containers of gerbera to a bright, frost free position for the winter month. Reduce watering, keeping the compost on the dry side particularly where growing in unheated conditions. Plants can be returned outdoors during the following spring, once all risk of frost has passed.

Established plants can be divided in March or April as the first signs of new growth are seen. Use healthy plants, dividing the rootstock and crown into four or five pieces each with one growth bud attached. Alternatively, detach young basal shoots, pot them up carefully in sandy compost, and place in a propagator until well rooted, then pot up or plant into a bed or border.