Getting it to bloom
Why won't my Rhododendron 'Catawbiense Boursault' bloom? (and how to make it flower)
Also called Boursault rhododendron (Rhododendron catawbiense 'Boursault').
More about rhododendron 'catawbiense boursault'
About Rhododendron 'Catawbiense Boursault'
Rhododendron catawbiense 'Boursault' · also called Boursault rhododendron · flowering
Rhododendron 'Catawbiense Boursault' is a tough, large, evergreen hybrid bearing rounded trusses of lilac-purple, lavender flowers in late spring. Derived from the cold-hardy Catawba rhododendron, it withstands harsh winters and suits acidic woodland borders and screens. All parts contain grayanotoxins and it is ASPCA toxic to cats and dogs.
Plant type: flowering
Watch for — Bud blast: Buds turn brown-black and fail to open, often with fine black bristles, linked to a fungus spread by leafhoppers. Remove affected buds and control leafhoppers.
The reasons rhododendron 'catawbiense boursault' isn't blooming
Almost every non-blooming rhododendron 'catawbiense boursault' 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 rhododendron 'catawbiense boursault' 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 rhododendron 'catawbiense boursault' to flower
- Maximise sun. Give rhododendron 'catawbiense boursault' 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 rhododendron 'catawbiense boursault' and get the feeding right with the rhododendron 'catawbiense boursault' 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
Rhododendron 'Catawbiense Boursault' 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 rhododendron 'catawbiense boursault' care brief and its watering schedule — a stressed, badly watered plant rarely has the energy to flower at all.
Rhododendron 'Catawbiense Boursault' blooming — frequently asked questions
Why won't my rhododendron 'catawbiense boursault' flower?
Rhododendron 'Catawbiense Boursault' 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 rhododendron 'catawbiense boursault' bloom?
Give rhododendron 'catawbiense boursault' 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 rhododendron 'catawbiense boursault' normally bloom?
Rhododendron 'Catawbiense Boursault' flowers across its growing season (mostly summer) and, kept fed and deadheaded, can bloom for many weeks or right up to frost.
What should I do with rhododendron 'catawbiense boursault' after it flowers?
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.
What is the single biggest mistake stopping rhododendron 'catawbiense boursault' flowering?
Feeding rhododendron 'catawbiense boursault' a high-nitrogen general feed and growing it in too little sun — you get a big leafy plant and almost no flowers.
Keep reading
- Rhododendron 'Catawbiense Boursault' care — the full brief (light, water, humidity, problems, pet safety)
- Rhododendron 'Catawbiense Boursault' light needs — usually the first thing to fix for flowers
- Rhododendron 'Catawbiense Boursault' fertilising — the right feed for buds, not just leaves
- Should I water my plant? The simple check
- Why is my plant wilting? Wet vs dry
- Underwatered plant — signs and rehydration
- Why won't my peace lily bloom?
- Why won't my jade plant bloom?
- Why won't my tomato bloom?
- All 639 bloom guides in the Growli library