Getting it to bloom

Why won't my Augustine's rhododendron bloom? (and how to make it flower)

Also called Augustine's rhododendron, Blue rhododendron (Rhododendron augustinii).

More about augustine's rhododendron

About Augustine's rhododendron

Rhododendron augustinii · also called Augustine's rhododendron, Blue rhododendron · flowering

Rhododendron augustinii is prized for its exceptional blue-to-lavender-purple flowers — among the closest to true blue in the genus. Native to southwest Chinese forests at 1,500–4,000 m, it forms an open, semi-evergreen to deciduous shrub. Blooms profusely in mid-spring and is a parent of many blue hybrid rhododendrons.

Plant type: flowering

Watch for — Late frost bud kill: The early-to-mid-spring bloom time coincides with late frosts in many regions. Flower buds turn brown and fail. Site in a sheltered position, or cover with horticultural fleece on forecast frost nights during the flowering window.

The reasons augustine's rhododendron isn't blooming

Almost every non-blooming augustine's rhododendron 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 augustine's rhododendron 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 augustine's rhododendron to flower

Maximise sun. Give augustine's rhododendron 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 augustine's rhododendron and get the feeding right with the augustine's rhododendron 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

Augustine's rhododendron 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 augustine's rhododendron care brief and its watering schedule — a stressed, badly watered plant rarely has the energy to flower at all.

Augustine's rhododendron blooming — frequently asked questions

Why won't my augustine's rhododendron flower?

Augustine's rhododendron 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 augustine's rhododendron bloom?

Give augustine's rhododendron 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 augustine's rhododendron normally bloom?