Winterizing a Perennial Garden in Cincinnati (Zone 5b-6a)

Your Cincinnati garden features a great mix of perennials. Here's a plant-by-plant winterizing plan for Zone 5b-6a, where winter lows hit -10°F to 0°F.

Tender Bulbs: Dig & Store

• Calla lily (Zantedeschia): After first frost kills foliage, dig corms, cut off dead tops, dry 1–2 weeks in a warm, airy spot. Store in peat moss or shredded paper in a mesh bag at 45–50°F. Replant after last frost when nights >50°F.

Herbaceous Perennials: Cut Back & Mulch

After several hard frosts (usually late November), cut these to 3–4 inches above ground. Remove debris to reduce disease carryover.

• Autumn Fire Sedum
• Speedwell 'Royal Candles' (Veronica)
• Lavender – only trim spent flower stalks; do not cut into woody base
• Wormwood 'Silver Mound' (Artemisia)
• Garden Mums ('Carmela', 'Tabitha') – cut to 6 inches

Woody Subshrub: Double Knock Out Rose

• Do not prune hard in fall. Remove only dead/diseased canes.
• Mound 8–10 inches of soil or compost over the base (crown) after ground freezes.
• Add a cylinder of chicken wire filled with leaves around the plant for extra protection.
• Major pruning: early April, when buds swell.

Mulching All Beds

Apply 2–3 inches of shredded leaves, pine needles, or bark mulch over all plants, extending 12–18 inches from crowns. This insulates roots, prevents freeze-thaw heaving, and conserves moisture.

What NOT to Do

• Don't fertilize after August.
• Don't use whole leaves that mat down—shred them first.
• Don't cover lavender or sedum crowns deeply; they rot in wet winter soil.

Follow this routine, and your perennials will emerge strong next spring.