I have seen many broccoli plants with purple leaves (mostly lower leaves), and still they are producing broccoli. The older leaves will naturally turn yellowish and then a bit purple. This is normal for a lot of broccoli varieties.
But in this article, I am not talking about that natural leaf aging. A lot of gardeners are witnessing a lot of broccoli leaves turning purple before they turn yellow. This is something that you need to be worried about.
When multiple broccoli leaves turn purple before fully maturing, it’s a sign that something is wrong and needs attention.
Too much sun releases a pigment that causes this. It's a cold-weather veggie. ( The same will happen if the weather is too cold) - The reason is stress.
The same issue occurs with other similar veggies like cauliflower.
Why are broccoli leaves turning purple
Let's understand why they turn purple. The purple color is from a pigment called anthocyanin, which the broccoli plant produces as a defence mechanism.
Broccoli releases this pigment more and more when the plant is under stress. This is something like, we get tan on our skin.
Due to a sudden cold or frost, the leaves might turn purple. And the same will happen when you forget to water your broccoli plant, and the soil is dry for more than 3 days, or the sun is too extreme.
All these reasons fall under stress:
- Too much sudden cold.
- Too much sun.
- Soil is dry for more than 3-5 days.
Note: Anthocyanin pigment is safe and edible. So when you see purple leaves on your broccoli, do not throw them away. They are safe to be consumed.
I grow broccoli mostly in the ground, but this year I tried it in small containers.
The container-grown broccoli leaves turned purple mostly. This is due to root stress. The roots need enough space to spread. Besides that, the container dries out more frequently than the ground.
What to do when you see purple broccoli leaves
I think a table would increase the readability.
| Symptom | Likely Cause | Action Needed |
|---|---|---|
| Purple on oldest leaves only (Lower leaves) | Phosphorus deficiency | Feed bone meal |
| Purple after cold nights | Cold stress | None (or use row covers) |
| Purple + stunted growth | pH or Root issues | Test soil pH (If planted in a container, repot) |
| Purple all over (healthy) | Variety genetics | None — enjoy the color! |
Now, a lot of people will ask how you would know if the temperature is too cold or not for your broccoli.
This is why I made this chart: When to cover plants in winter - complete chart
There you will find cold tolerance for each plant, including broccoli.
A tip that I received from my aunt, here's her quote:
"Compost tea made them look much happier, as did increasing the amount of water I was giving them. I put mine in a new garden bed, and the soil is kind of underwhelming. I should have amended it more."
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