Check these first
- Are the stems stretched with long gaps between leaves? That is a lack of light.
- Are new leaves curled, twisted, or unusually small? Think virus or sap-sucking pests.
- Are the leaves dark and lush but there are no flowers or fruit? That is too much nitrogen.
Most likely causes
From the pests and diseases recorded for this plant, the ones whose symptoms match, most serious first. Symptoms alone rarely confirm a cause, so use the linked page to check the signs and treatment.
Clubroot
Leaves wilt during the day and recover morning and evening, and growth is markedly poor. Pull the plant and the roots carry many spindle-shaped or irregular galls.
How to identify and treat: ClubrootFusarium Yellows
Yellowing starts on the lower leaves, the petioles twist and the plant leans to one side. Vascular tissue browns, growth stops, and heading vegetables may die without ever forming a head.
General description; not specific to this plant.
How to identify and treat: Fusarium YellowsOnion Thrips
Fine white stippled scars run in vertical lines along the leaf surface, and the whole leaf eventually turns whitish. Growth stops and both yield and quality suffer.
General description; not specific to this plant.
How to identify and treat: Onion ThripsOther possible causes
The three above are the causes on record for this symptom.
Other symptoms on this plant
What other growers did about it
A page like this one can tell you what broccoli not growing well is and what to try. What it cannot tell you is what actually happened to someone who had it on the same plant, at the same point in the season, and what they did next.
Gadenin is a free garden journal built around that. You photograph the plant, tag what you are seeing, and the entries line up by date for each plant you grow.
- Tag the problem and the app tells you how many other growers have logged the same thing on the same plant.
- Growers who make their records public can be followed, so you can read what they did and how it turned out.
- Next season your own entries come back at the same point in the year, so you check the plant before it starts.
Free on iPhone. Recording, tagging and reading public records cost nothing.