Are Your Petunias Leggy? Midsummer Cutback and Feeding
The short answer
Are your petunias leggy by midsummer? Bare stems with flowers only at the tips are common. Clemson Extension says to cut leggy shoots back to about half their length, feed with a liquid fertilizer and water well. N.C. Cooperative Extension says new blooms return in a week or two. Full sun and steady feeding help plants fill out.
Why are my petunias getting leggy?
Light is the first cause. University of Minnesota Extension says petunias need at least 5 or 6 hours of good sun and do even better in full sun all day. Clemson Extension says petunias grown in shade become spindly and have few flowers. N.C. Cooperative Extension in Richmond County agrees shade means fewer blooms. Low light makes many plants stretch, as how to control and prevent stretching in cannabis plants explains.
Type matters too. N.C. Cooperative Extension notes that seeded varieties must be deadheaded, since the plant’s goal is to set seed. Vegetative varieties are bred to bloom without stopping and are self cleaning, so deadheading is optional. Hunger and drought add stress. For more on how stress shows up, read the effects of environmental stresses on weed plants.
How do you cut back leggy petunias?
| Fix | When | Notes |
|---|---|---|
| Light trim | Through the season | Cut about 20 percent back to a bud or node |
| Hard cutback | When plants are leggy or stop flowering | Cut shoots to about half their length |
| Pinch | At about six inches tall | Grandifloras and multifloras only |
| Deadhead | As flowers fade | Remove the flower and the seed part below it |
Sources: Clemson Extension, N.C. Cooperative Extension, University of Minnesota Extension.
Clemson says you can cut to within a few inches of the base if needed, but don’t strip all the leaves. N.C. Cooperative Extension suggests pruning long stems back to a bud or node and says a cut all at once takes a week or two to bloom again. To skip a bare look, prune a little at a time. Minnesota adds that young grandifloras and multifloras can be pinched at about six inches tall, but millifloras and spreading types should not be pinched. For general cutting skills, see pruning marijuana plants.
Do petunias need regular feeding?
Yes. N.C. Cooperative Extension calls petunias hungry plants that do well when fed once or twice a week with a complete water soluble fertilizer. Minnesota says to start liquid fertilizer in early to mid July, every 3 weeks in the garden and every 2 weeks in containers. Spreading types need weekly feeding. Clemson suggests a balanced fertilizer monthly and a liquid feed after a cutback.
Water evenly. Minnesota says one deep watering a week suits most garden petunias, but spreading types and pots need more, sometimes daily.
How to: step by step
- Check that the bed gets at least 5 or 6 hours of sun.
- Cut leggy shoots back to about half, to a bud or node.
- Leave some leaves on every stem.
- Feed with a liquid fertilizer.
- Water well to push new growth.
- Deadhead seeded types as flowers fade.
- Feed every 1 to 3 weeks through summer.
Troubleshooting
Long bare stems: no cutback. Clemson says to cut shoots to about half their length, then feed and water.
Few flowers in shade: low light. Minnesota and Clemson both say shade means fewer blooms, so move pots into full sun.
Flowering stopped: seed is forming. Deadhead seeded types and remove the part below each flower, as N.C. Cooperative Extension and Minnesota describe.
Plants wilting: too dry. N.C. Cooperative Extension says petunias wilt when dry but usually recover once watered.
Fresh color into fall
Cut back, feed and give full sun, and petunias bloom into fall. Find more garden ideas on the Kind Seed Co blog.
Sources
- Secrets to have petunias last all season long, N.C. Cooperative Extension, Richmond County Center
- Growing petunias, University of Minnesota Extension
- Petunia, Clemson Cooperative Extension Home and Garden Information Center
FAQ
Do all petunias need deadheading?
No. N.C. Cooperative Extension says seeded varieties must be deadheaded, but vegetative varieties are self cleaning, so deadheading is optional. Clemson Extension says large flowered and double petunias need it, while many smaller flowered types are self cleaning.
How often should petunias be fed?
N.C. Cooperative Extension suggests a complete water soluble fertilizer once or twice a week. University of Minnesota Extension says liquid feed every 3 weeks in beds and every 2 weeks in containers from early to mid July, and weekly for spreading types.
Will petunias bloom again after cutting back?
Yes. N.C. Cooperative Extension says plants cut back all at once may take a week or two to put new blooms on. Clemson Extension says to feed with a liquid fertilizer and water well after the cut to force out new growth and flowers.
Do petunias in pots need more care?
Yes. University of Minnesota Extension says containers and hanging baskets need more frequent watering, perhaps daily, and regular liquid feeding every 2 weeks. It also says deadheading is a must for flowering annuals in containers.
How much sun do petunias need?
University of Minnesota Extension says at least 5 or 6 hours of good sun, and better in full sun all day. N.C. Cooperative Extension says at least 6 hours, and Clemson Extension says plants in shade turn spindly with few flowers.
