Verbascum Growing Guide

Verbascum phoeniceum and Verbascum chaixii hybrids, Verbascum thapsis (common mullein)

Crop Rotation Group

Miscellaneous ●

Soil

Fertile, well-drained soil with a slightly alkaline pH.

Position

Full sun.

Frost tolerant

Yes, verbascums are hardy biennials or perennials. Plants are hardy to about -15°F (-26°C).

Feeding

Mulch over the plants’ root zones with rich compost just as new growth emerges in spring. Drench plants with a liquid fertilizer when they begin to grow tall.

Spacing

Single Plants: 11" (30cm) each way (minimum)
Rows: 11" (30cm) with 11" (30cm) row gap (minimum)

Sow and Plant

Verbascum can be started from seeds or from purchased plants. Start seeds indoors in late winter and expect germination in 14 days at room temperature. Grow seedlings under strong supplemental light, and start hardening them off when they have five true leaves. Verbascums that are set out early so they receive some winter chilling are likely to bloom their first year. Depending on climate and verbascum variety, plants may be annual, biennial or perennial. Young plants need water when they are actively growing, but become very drought resistant after they develop deep taproots.
Our Garden Planner can produce a personalized calendar of when to sow, plant and harvest for your area.

Notes

Many beautiful verbascum varieties have been developed that deserve wider use in gardens. Those that bloom in purple and pink produce flowers in early summer, while yellow and orange strains bloom later because of their varied lineages.

Harvesting

Gather stems for use in cut arrangements as you need them, when at least half of the flowers on a stem are open. Cutting old blossoms will stimulate modest reblooming. Allow a few spikes to stay on the plants until they shed mature seeds. When happy with their site, verbascums are often successful reseeders.

Planting and Harvesting Calendar

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Pests which Affect Verbascum

Aphids (General)

Slug

Snail