When and how to deadhead summer flowers (and the 5 you shouldn't)

Deadheading is just removing flowers that have finished blooming — but it tricks the plant. From the plant's perspective, blooming exists to make seeds. Once the seeds are forming, the plant slows or stops making new flowers. Cut the spent blooms off and you intercept that signal: the plant keeps trying to reproduce, which means more flowers for you.

For most summer bloomers, regular deadheading extends the bloom season by 4–6 weeks and noticeably improves how the plant looks day-to-day.

The 10-minute weekly routine

Walk the bed once a week with a small pair of pruners. Don't try to be precise about identifying every spent bloom — just look for:

1. Petals that have faded or fallen. The center has turned brown or formed a seed head.
2. Flower stems that are bent or wilted while neighboring stems are still upright.
3. Anything that looks "tired" compared to nearby healthy blooms.

Cut just above the next leaf node or pair of leaves below the spent flower. That's where the plant has dormant buds that will become the next round of blooms.

The technique that matters

For most flowers, a clean cut with sharp pruners is all you need. But three details separate good deadheading from busywork:

• Cut, don't pull. Pulling can rip stems and create entry points for disease.
• Get the whole stem, not just the petals. Snapping off petals leaves the seed-forming structure behind, which defeats the point. Cut down to the next branching node.
• Sterilize between diseased plants. If you've been working on a plant with leaf spot or mildew, wipe pruners with rubbing alcohol before moving to the next one.

What to deadhead aggressively

These respond dramatically to weekly deadheading — you'll get 2–3× the total bloom season:

• Zinnias. Cut deep, all the way to the next set of leaves. They'll branch and produce more flowers than you started with.
• Cosmos. Same approach as zinnias.
• Petunias. Pinch off the entire spent flower including the base — the green part swells with seed if you leave it.
• Marigolds. Snap off below the swollen base.
• Dahlias. Cut on the stem at a leaf joint. Dahlias also benefit from "disbudding" — removing the two side buds next to the central one — for fewer but larger blooms.
• Roses. Cut at a 45° angle just above the first 5-leaflet leaf. Modern reblooming varieties will push another flush of blooms in 5–7 weeks.

What NOT to deadhead

Some plants either don't benefit, or you'll lose something valuable by deadheading them:

1. Coneflowers (echinacea) — leave the seed heads. Goldfinches eat the seeds in fall, and the dried heads add winter structure to the bed.
2. Black-eyed susans (rudbeckia) — same deal. Birds love the seeds, and the dark cones are striking against snow.
3. Sedums. The dried flower heads are part of the plant's appeal in late fall and winter.
4. Native asters. Late-season pollinators (especially specialist bees) depend on aster pollen well after most other blooms are done.
5. Hydrangeas (most varieties). Deadheading hydrangeas is more about pruning than per-bloom — and removing spent blooms in late summer can actually damage next year's flower buds. Cut hydrangeas in early spring, not summer.

When deadheading stops working

Late August through mid-September, even diligent deadheading on annuals starts producing fewer flowers and smaller ones. The plant is responding to shortening day length, not seed pressure. That's the natural end of the season — pull the plants and replace with mums or pansies for fall color.

Want a bed that does most of this work for you? GimmeBlooms designs beds with bloom-succession built in — so as one species winds down, another peaks. See an example bed.