Getting it to bloom

Why won't my Hairy St John's-wort bloom? (and how to make it flower)

Also called Hairy St John's-wort, Hairy St John's Wort (Hypericum hirsutum).

More about hairy st john's-wort

About Hairy St John's-wort

Hypericum hirsutum · also called Hairy St John's-wort, Hairy St John's Wort · flowering

Hypericum hirsutum is a softly hairy, erect perennial native to calcareous woodland edges, scrub, and hedgebanks across the UK and Europe, reaching 40–80 cm with terminal clusters of pale yellow five-petalled flowers from July to August. It grows in partial to full shade, tolerating conditions too shady for most Hypericum species, and prefers moist, well-drained soils. The most important care fact is that, like all members of the genus, it contains hypericin, which is toxic to cats, dogs, and horses. Keep pets away from all parts of the plant.

Plant type: flowering

Watch for — Aphid infestations: Colonies of greenfly can build up on young shoot tips in spring; blast off with water or apply insecticidal soap — avoid systemic insecticides near flowering plants where pollinators are active.

The reasons hairy st john's-wort isn't blooming

Almost every non-blooming hairy st john's-wort 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 hairy st john's-wort 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 hairy st john's-wort to flower

Maximise sun. Give hairy st john's-wort 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 hairy st john's-wort and get the feeding right with the hairy st john's-wort 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

Hairy St John's-wort 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 hairy st john's-wort care brief and its watering schedule — a stressed, badly watered plant rarely has the energy to flower at all.

Hairy St John's-wort blooming — frequently asked questions

Why won't my hairy st john's-wort flower?

Hairy St John's-wort 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 hairy st john's-wort bloom?

Give hairy st john's-wort 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 hairy st john's-wort normally bloom?