Do these plants bloom indoors?

They rarely bloom indoors because it is difficult to provide the specific light and dark cycles they require. They are best suited for outdoor gardens.

How long does it take to flower?

Once the plant reaches a certain size and the nights become long enough, it will typically begin to flower within 2 to 4 weeks.

Rough cocklebur: not flowering, causes and fixes

Check these first

Observe the plant location for nearby artificial light sources at night.
Measure the hours of darkness the plant receives over a 24 hour period.
Check the soil fertility to ensure it is not overly rich in nitrogen.

Likely causes

Insufficient darkness
Most likely
How to tell: The plant remains in a vegetative state and continues to grow leaves without forming burs.
What to do: Ensure the plant experiences at least 10 to 12 hours of uninterrupted darkness every night. Move the plant away from streetlights or porch lights that might disrupt this cycle.
Excessive nitrogen
Possible
How to tell: The plant is lush and green but shows no interest in reproductive growth.
What to do: Switch to a fertilizer lower in nitrogen and higher in phosphorus. Apply this once every 4 weeks during the growing season to encourage bud formation.

Other plants that won't flower

Find out what's wrong with your rough cocklebur

The list above covers the usual causes. Pocket Botanist looks at a photo of your actual plant and tells you the likely cause, how serious it is, and what to try first. Identification and a health check are free.

When to worry

If the plant has reached maturity and the days are naturally shortening, it should begin to flower. If it remains strictly vegetative through the end of the season, it is likely not receiving the correct light cues.

Stopping it coming back

Keep the plant in a location where it is not exposed to artificial light after sunset during the late summer months.

Rough cocklebur: not flowering? Check yours with a photo

Every plant is a little different. Take a photo of your rough cocklebur and Pocket Botanist tells you which cause is most likely, how serious it is, and what to try first. A few checks a day are free. Save the plant and you get care reminders timed for it.

Get the app · Or check it from a photo now, free

Questions people ask

Do these plants bloom indoors?: They rarely bloom indoors because it is difficult to provide the specific light and dark cycles they require. They are best suited for outdoor gardens.
How long does it take to flower?: Once the plant reaches a certain size and the nights become long enough, it will typically begin to flower within 2 to 4 weeks.

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