September's Pruning | What to Prune & What to Avoid
As September approaches in Lodi, our gardens are beginning the transition from summer heat to fall. It’s tempting to reach for the pruning shears and start cleaning everything up—but some plants benefit from a late-summer trim, while others are best left alone.
Here are 10 plants to consider pruning now—and several you should resist cutting back.
1. Lavender — Lightly Prune
Once summer flowering has finished, trim off spent flower stalks and lightly shape the plant. You can remove some of this year’s soft green growth, but don't cut deeply into old, woody stems, which may not readily produce new growth.
2. Wisteria — Prune
Late summer is a good time for wisteria's second pruning. Shorten the long, vigorous shoots that have grown during summer, generally leaving several leaves on each side shoot. This helps control its size and encourages the development of flowering spurs.
3. Salvia — Prune
Many salvias become leggy by late summer. Deadhead spent flowers and lightly cut back tired growth. With Lodi's long growing season, many varieties will reward you with another flush of flowers well into fall.
4. Roses — Lightly Prune
September isn't the time for the major annual rose pruning—that comes during winter dormancy. For now, deadhead spent flowers, remove dead or damaged growth and lightly shape unruly plants. Avoid a hard pruning that encourages lots of tender new growth heading into fall.
5. Geraniums (Pelargoniums) — Prune
After a long, hot Lodi summer, geraniums can become woody and leggy. Remove spent flowers and cut back excessively long stems to encourage fresh, compact growth as temperatures moderate.
6. Catmint — Prune
If your catmint is sprawling or looking tired, shear back the spent flower stems and untidy growth. It may respond with fresh foliage and another round of blooms.
7. Yarrow — Prune
Remove old flower stalks and cut back tired foliage. Leave healthy basal growth in place. If you want yarrow to reseed naturally, leave a few flower heads standing.
8. Agapanthus — Remove Flower Stalks
Once the flowers have faded, cut the stalks down near the base. Leave the green foliage alone—the leaves are still feeding the plant.
9. Daylilies — Clean Up
Remove spent flower stalks and yellow or damaged foliage, but don't feel compelled to cut the entire plant to the ground while substantial green foliage remains.
10. Summer-Flowering Perennials — Tidy, Don't Scalp
Coreopsis and other summer-blooming perennials can benefit from deadheading and removal of tired growth. Think of September pruning as a tidying and rejuvenating session rather than a major haircut.
Put Down the Pruning Shears!
Some plants are better left alone in September.
Peonies
Don't cut healthy green foliage yet. The leaves continue producing energy for next year's growth. Wait until the foliage naturally yellows or dies back in fall before cutting it to the ground.
Bleeding Heart
If the foliage has naturally yellowed and died back, it can be removed. But if your plant is still green, leave it alone and allow it to finish storing energy for next spring.
Spring-flowering shrubs
Be cautious with azaleas, camellias and other shrubs that bloom on older growth. Many are already developing the buds that will produce next year's flowers. A poorly timed pruning can mean pruning away the show before it ever happens.
Hydrangeas
Know which type you have before pruning. Some bloom on old wood, and cutting them back now can remove next year's flower buds.
Citrus
September isn't the time for aggressive pruning. Remove dead, damaged or troublesome growth as necessary, but save major shaping for a more appropriate time.
The September Rule: Prune With a Purpose
In Lodi's Zone 9 climate, September can still bring plenty of hot weather. Rather than giving the entire garden a fall haircut, deadhead, lightly shape and remove damaged or exhausted growth.
And before cutting back a plant, ask one question:
Does this plant need pruning now—or do I just want the garden to look tidier?
Sometimes the best September gardening decision is simply to put the pruning shears back in the shed.
Download our September Garden Checklist for easy reference.
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