When the plant is too small to deadhead, such as ageratum and alyssum, then pinch the entire plant back twice during the summer.
This will allow the side shoots to develop and flower.
Petunias will become leggy and scraggly by the first of August.
When you pinch these plants back by half we may limit flower production for a week, but should give us a bushy plant that will produce flowers until the first frost.
After pinching plants back apply fertilizer to stimulate growth. Using a complete garden fertilizer (10-10-10) applied to a rate of half-pound per 100 square feet of flowers should be best.
If the flowers are not bunched together, then a tablespoon of fertilizer per plant will work. Lightly scratch the fertilizer into the soil and water it in for best results.
Flowers will not thrive unless there is enough water to produce new growth.
The rule of thumb is an inch of water per week in order to bloom. This works great if the temperatures are less the 90 degrees Fahrenheit.
Temperatures higher than 90 will require up to two inches of water per week when no rainfall.
We have found a sprinkler or soaker hose works best. Watering should be done in the morning. When watered at night the leaves do not have time to dry and will increase the chance of diseases.
Water once or twice a week instead of each day.
Good organic mulch keeps the soil cool, retains water, reduces weeds and prevents many disease problems.
Three to four inches of compost, peat moss or wood chips help keep the flowers blooming.