Getting it to bloom

Why won't my Moth Mullein bloom? (and how to make it flower)

Also called Moth Mullein, Moth Verbascum (Verbascum blattaria).

More about moth mullein

About Moth Mullein

Verbascum blattaria · also called Moth Mullein, Moth Verbascum · flowering

Moth Mullein is a slender, graceful biennial or short-lived perennial producing tall, elegant spikes of yellow or white flowers with distinctive purple-hairy stamens that resemble antennae — giving the plant its common name. Native to Europe and western Asia, it naturalises readily in dry, sunny conditions and is a valuable pollinator plant with a long summer blooming season.

Plant type: flowering

Watch for — Mullein moth (Cucullia verbasci): Caterpillars feed on flowers and leaves in late spring; the slender spikes of moth mullein are particularly vulnerable to complete defoliation — inspect regularly and remove caterpillars by hand or apply Bt biological spray.

The reasons moth mullein isn't blooming

Almost every non-blooming moth mullein traces back to one of these, roughly in order of how common they are:

Too little sun — most of these need full sun (or very bright light) to flower well; shade gives leaves, not blooms.
Too much nitrogen feed, driving lush foliage at the expense of flowers (very common with general or lawn feeds).
The plant has not been deadheaded, so it stops flowering once it sets seed.
Irregular watering — drought or waterlogging at the budding stage makes buds abort.
It is still too young or was checked by a transplant and is rebuilding before flowering.

Feeding moth mullein a high-nitrogen general feed and growing it in too little sun — you get a big leafy plant and almost no flowers.

The fix — how to get moth mullein to flower

Maximise sun. Give moth mullein the sunniest spot you have — for most bedding and fruiting plants, more direct light directly means more flowers.
Switch the feed. Move off high-nitrogen feeds and use a higher-potassium "bloom" or tomato-type feed as it comes into flower.
Deadhead regularly. Remove spent flowers often to keep it producing more rather than stopping to set seed.
Water consistently. Keep moisture even through budding and flowering — drought-then-flood swings make buds drop.

Light and feeding do most of the heavy lifting here. Dial in the spot with the light guide for moth mullein and get the feeding right with the moth mullein fertilising schedule — the wrong feed (too much nitrogen) is one of the most common silent reasons a healthy plant makes leaves instead of flowers.

Bloom season and what to expect

Moth Mullein flowers across its growing season (mostly summer) and, kept fed and deadheaded, can bloom for many weeks or right up to frost.

Post-bloom care so it flowers again

Deadhead, keep feeding lightly, and many will rebloom; collect seed from the best plants at the end of the season if you want to grow them again.

For everything else this plant needs day to day, see the full moth mullein care brief and its watering schedule — a stressed, badly watered plant rarely has the energy to flower at all.

Moth Mullein blooming — frequently asked questions

Why won't my moth mullein flower?

Moth Mullein blooms on the season's growth given enough sun, warmth and the right feed — there is no cold or photoperiod trick, just good growing conditions and a bloom-leaning feed. The most common reason it is not happening: Too little sun — most of these need full sun (or very bright light) to flower well; shade gives leaves, not blooms.

How do I make moth mullein bloom?

Give moth mullein the sunniest spot you have — for most bedding and fruiting plants, more direct light directly means more flowers. Move off high-nitrogen feeds and use a higher-potassium "bloom" or tomato-type feed as it comes into flower.

When does moth mullein normally bloom?