Getting it to bloom

Why won't my Blue blossom bloom? (and how to make it flower)

Also called blue blossom, blueblossom ceanothus, California lilac (Ceanothus thyrsiflorus).

More about blue blossom

About Blue blossom

Ceanothus thyrsiflorus · also called blue blossom, blueblossom ceanothus · flowering

Blue blossom is a vigorous, evergreen shrub or small tree native to coastal California and Oregon, producing masses of powder-blue to deep blue flowers in late spring. One of the hardiest and largest-growing Ceanothus species, it thrives in free-draining, poor soils and full sun. Ideal for coastal gardens, slopes, and informal screens in mild temperate climates.

Plant type: flowering

Watch for — Frost damage to shoot tips: Young growth in late winter or early spring can be browned by late frosts in marginal climates. Protect newly planted specimens with fleece during forecast frosts. Avoid pruning in autumn, which stimulates tender new growth before winter. Prune only lightly immediately after flowering.

The reasons blue blossom isn't blooming

Almost every non-blooming blue blossom 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 blue blossom 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 blue blossom to flower

Maximise sun. Give blue blossom 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 blue blossom and get the feeding right with the blue blossom 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

Blue blossom 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 blue blossom care brief and its watering schedule — a stressed, badly watered plant rarely has the energy to flower at all.

Blue blossom blooming — frequently asked questions

Why won't my blue blossom flower?

Blue blossom 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 blue blossom bloom?

Give blue blossom 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 blue blossom normally bloom?