Getting it to bloom

Why won't my Lythrum salicaria bloom? (and how to make it flower)

Also called Purple Loosestrife, Spiked Loosestrife (Lythrum salicaria).

More about lythrum salicaria

About Lythrum salicaria

Lythrum salicaria · also called Purple Loosestrife, Spiked Loosestrife · flowering

Purple loosestrife is a tall, clump-forming wetland perennial native to Europe and Asia, with upright stems topped by dense spikes of magenta-purple summer flowers that draw bees and butterflies. Striking in a bog garden or pond margin, it is also a notorious invasive in North American wetlands, where planting is restricted or banned, so check local regulations before growing it.

Plant type: flowering

Watch for — Prolific self-seeding: One plant can shed enormous numbers of seeds that spread on water and wind. Deadhead spent flower spikes promptly if you grow it, to prevent uncontrolled colonisation.

The reasons lythrum salicaria isn't blooming

Almost every non-blooming lythrum salicaria 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 lythrum salicaria 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 lythrum salicaria to flower

Maximise sun. Give lythrum salicaria 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 lythrum salicaria and get the feeding right with the lythrum salicaria 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

Lythrum salicaria 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 lythrum salicaria care brief and its watering schedule — a stressed, badly watered plant rarely has the energy to flower at all.

Lythrum salicaria blooming — frequently asked questions

Why won't my lythrum salicaria flower?

Lythrum salicaria 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 lythrum salicaria bloom?

Give lythrum salicaria 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 lythrum salicaria normally bloom?