The following tips are cultural guidelines to assist growing potted gerberas.

Ensure grown in a free draining mix, and that irrigation is only applied in the morning. (avoid afternoon/evening)this helps avoid Crown/Root Rots and Mildews.

Never over water a gerbera and let each watering dry out before rewetting.  Avoid excess water on foliage, if you do water in the afternoon, make sure the leaves dry off before evening. Gerberas are very prone to Powdery Mildew.

Gerberas should be well spaced, avoid a lot of shading and grow in full sunlight to partial shade in afternoon (in summer) for best results.

Don’t plant Gerberas too deep or have mulch too close to stem, this can cause Crown Rot.
Remove spent blooms and remove flowering stalks of wilted blooms at the crown to encourage further flowering.

Fertilise plants regularly with Phosphorus and Potassium ratios to encourage flowering. (not excessive)
Always remove yellow, diseased or pest infected leaves, to avoid fungal diseases.

Mildews thrive in high humidity (80-90%), moderate temps (19-26c), overcrowding and shading of plants.

Bottom irrigation is effective with Gerberas but overhead can be just as effective, if managed effectively (avoid late, don’t overwater and dry off) by washing spores from surface of leaves.

Reduce mildews through  good ventilation, sunny areas, avoiding excessive fertilisation and rotation of protectant fungicides.(Coppers, Oils, Sulphurs, Phosphorus Acids etc)
Following these simple guidelines will greatly assist you in growing on a quality Gerbera for you to enjoy.