I mostly limit my gardening to my organic veggie garden, but I do love the look of flowers around the house. I love petunias for their bright, happy looking flowers, but somehow mine always end up looking leggy and ragged a few weeks after I bring them home from the nursery. I did a search on the web to find the answers to the burning question of how to properly care for and prune petunias. Here is what I found.
This article from SFGate has a good basic step by step for cutting back petunias.
Locate a node or point at least half way between the tip and base of the main stem where smaller stems or leaves branch. When petunias produce long stems with few leaves and stop producing flowers, trimming them back improves the overall look and promotes new growth and flower production. Make these pruning cuts in mid-summer.
This video has a nice demonstration where to clip the stems (at about 1:57 seconds he shows the part of the stem that you should remove behind the spent flower).
And this article from gardenlady.com does a very good job of explaining how to keep your petunias full of flowers and bushy vs. “stemmy”
If you look at your petunia plants you will notice that they only form flowers at the END of the stems. So as the stems grow longer all the flowers are at the edges of the plants, with bare stems leading up to them. This is the case if you are growing the Wave, Super Petunias or regular ones.
In order to keep the plants full, bushy and not “stemmy” – you need to clip some of the stems each week.
And here’s some really great advice for rejuvenating a stemmy plant and even rooting the cuttings that you take from the plant… and who doesn’t love MORE plants for FREE??
What should you do if your plant is “stemmy” or has stopped flowering? Clip the stems back by 2/3 and fertilize. You could clip all at once, or do a third at a time (randomly over the plant – clip a third every week or 10 days) so that the plant isn’t cut back all at once.
You can also root the ends of the stems you clip off – cut them to 8″ long and put them in fresh, damp potting soil after coating the stems with rooting hormone.
Lastly, don’t forget to fertilize! The GardenLady recommends every three weeks. Always water first, never fertilize a thirsty plant.