Getting it to bloom
Why won't my Cosmos sulphureus 'Bright Lights' bloom? (and how to make it flower)
Also called Bright Lights Sulphur Cosmos, Orange Cosmos (Cosmos sulphureus 'Bright Lights').
More about cosmos sulphureus 'bright lights'
About Cosmos sulphureus 'Bright Lights'
Cosmos sulphureus 'Bright Lights' · also called Bright Lights Sulphur Cosmos, Orange Cosmos · flowering
'Bright Lights' is a sulphur cosmos bearing semi-double blooms in vivid orange, gold and yellow over more sharply toothed, less ferny foliage than garden cosmos. Heat- and drought-loving, it is shorter and bushier than C. bipinnatus and flowers tirelessly from summer to frost, drawing bees and butterflies. It thrives on neglect in poor, well-drained soil and full sun.
Plant type: flowering
Watch for — Few flowers, lots of leaves: Rich soil or feeding pushes foliage. Grow in poor, well-drained soil and withhold fertiliser to maximise blooms.
The reasons cosmos sulphureus 'bright lights' isn't blooming
Almost every non-blooming cosmos sulphureus 'bright lights' 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 cosmos sulphureus 'bright lights' 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 cosmos sulphureus 'bright lights' to flower
- Maximise sun. Give cosmos sulphureus 'bright lights' 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 cosmos sulphureus 'bright lights' and get the feeding right with the cosmos sulphureus 'bright lights' 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
Cosmos sulphureus 'Bright Lights' 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 cosmos sulphureus 'bright lights' care brief and its watering schedule — a stressed, badly watered plant rarely has the energy to flower at all.
Cosmos sulphureus 'Bright Lights' blooming — frequently asked questions
Why won't my cosmos sulphureus 'bright lights' flower?
Cosmos sulphureus 'Bright Lights' 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 cosmos sulphureus 'bright lights' bloom?
Give cosmos sulphureus 'bright lights' 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 cosmos sulphureus 'bright lights' normally bloom?
Cosmos sulphureus 'Bright Lights' 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 cosmos sulphureus 'bright lights' 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 cosmos sulphureus 'bright lights' flowering?
Feeding cosmos sulphureus 'bright lights' a high-nitrogen general feed and growing it in too little sun — you get a big leafy plant and almost no flowers.
Keep reading
- Cosmos sulphureus 'Bright Lights' care — the full brief (light, water, humidity, problems, pet safety)
- Cosmos sulphureus 'Bright Lights' light needs — usually the first thing to fix for flowers
- Cosmos sulphureus 'Bright Lights' 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 2023 bloom guides in the Growli library