Petunias, known scientifically as Petunia x hybrida, are herbaceous perennial flowering plants that, due to their tender nature, are grown as annuals in most of the UK. When their growing conditions are not ideal, petunias often become all foliage and few flowers, earning them the nickname leggy petunias. As a gardener, there are several things you can do to correct the legginess of your petunias. With a little special care, you'll have beautiful petunias that are the envy of your neighbourhood.
Plant your petunias in a location that receives six to eight hours of full sunlight each day. If you live in a particularly warm climate, it's a good idea to plant your petunias in a location where they can receive partial shade from the hot afternoon sun.
Deadhead your petunias by pinching or snipping off spent blossoms to encourage your plant to produce healthy new blooms.
Water your petunias less frequently if their foliage becomes leggy. Petunias will often become leggy in response to being over-watered. Water your petunias, as needed, to keep their soil just slightly moist. Allow the top 1.2 cm (1/2 inch) of soil to dry out between watering to avoid giving your petunias too much moisture.
Enrich and aerate the soil at your planting location to improve drainage if you notice standing water at the base of your petunias. Hand till amendments like aged manure, rotted leaves and peat moss into the top 7 or 8 cm (3 inches) of soil around your petunias.
Cut the stems of your petunia plant back to half their length in midsummer to encourage your petunias to produce new growth. Water your petunias and fertilise them with a balanced 10-10-10 fertiliser after pruning.
Growing a different variety of petunia can eliminate your problem of having petunias with leggy foliage. Petunia varieties that grow without becoming leggy include cultivars from the Wave series, as well as the Supertunia, Petitunia, Sanguna, Tiny Tunia, Plush and Suncatcher varieties.
Monitor your petunias for aphids and other insect activity. Treat your flowers with a garden insecticide, if necessary.