Getting it to bloom

Why won't my Ivy-leaved Duckweed bloom? (and how to make it flower)

Also called Ivy-leaved Duckweed, Star Duckweed (Lemna trisulca).

More about ivy-leaved duckweed

About Ivy-leaved Duckweed

Lemna trisulca · also called Ivy-leaved Duckweed, Star Duckweed · flowering

Ivy-leaved Duckweed is a distinctive submerged duckweed native to Europe, Asia, and North America, forming translucent pale-green fronds connected in branching chains beneath the water surface. Unlike other duckweeds, it stays submerged until flowering. An excellent oxygenator and fish food plant for wildlife ponds and aquaria. Hardy and low-maintenance.

Plant type: flowering

Watch for — Surface mat formation at flowering: When plants briefly surface to flower, they can temporarily form a surface mat. This is a natural behaviour; skim lightly if it shades submerged planting or fish, but avoid removing all surface material.

The reasons ivy-leaved duckweed isn't blooming

Almost every non-blooming ivy-leaved duckweed 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 ivy-leaved duckweed 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 ivy-leaved duckweed to flower

Maximise sun. Give ivy-leaved duckweed 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 ivy-leaved duckweed and get the feeding right with the ivy-leaved duckweed 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

Ivy-leaved Duckweed 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 ivy-leaved duckweed care brief and its watering schedule — a stressed, badly watered plant rarely has the energy to flower at all.

Ivy-leaved Duckweed blooming — frequently asked questions

Why won't my ivy-leaved duckweed flower?

Ivy-leaved Duckweed 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 ivy-leaved duckweed bloom?

Give ivy-leaved duckweed 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 ivy-leaved duckweed normally bloom?