Question
How do I keep my petunias from becoming leggy

Answer
Vicky, when petunias receive too much fertilization, especially with a fertilizer high in nitrogen, they can become spindly. They will also get leggy when they are not kept pruned.

To correct this, you must prune them like a bush, shaping them into a round mound. I would suggest cutting the plants back by a third. They should then develop a bushier habit and bloom several more times before your first frost.  

In the future, use a fertilizer high in phosphorus and potassium, but low in nitrogen. Phosphorus encourages blooming, while nitrogen results in taller plants and more foliage. Also, add organic amendments to the soil this fall, such as shredded leaves, compost, peat moss, and aged manure. This will help improve the soil and neutralize any imbalance in your ph levels.  

I hope this helps. Good luck, and please write again if I can ever be of assistance.  

Regards,  

Mike