GrowSabzHow to grow collard greens in pots
Also called collards, borecole · Brassica oleracea var. viridis
کولارڈ گرینز
- ☀️ Sunlight
- 6–8hours daily
- 💧 Water
- 0.8 Levery 2 days, 10 L pot
- 🌡️ Ideal temp
- 13–24°C
- 🪴 Min pot
- 10 L25 cm deep
- 🧺 Harvest
- 60–75days from sowing
- ⚖️ Yield
- 3 kgper 20 L pot
Collard Greens keeps producing once it starts. First picking comes around day 60, and the plant then crops for roughly 90 more days — but only if you keep picking. Letting it run to flower is what ends the supply.
Short answer
Grow collard greens in a 10 litre container at least 25 cm deep, watering about 700 ml per 10 litres of soil every 2 days, and keep temperatures between 13 and 24 °C. First harvest comes 60–75 days after sowing.
Where to plant it
What size pot does collard greens need?
10 litres and 25 cm deep is the realistic minimum for a single plant. Pick a container below to see what changes.
| Container | Minimum size | Depth | Notes |
|---|---|---|---|
| Pot | 10 L | 25 cm | Ensure good drainage |
| Grow bag | 10 L | 25 cm | Fabric bags promote air pruning |
| Open ground | — | 30 cm | Space plants 15-30 cm apart |
| Raised bed | 20 L | 30 cm | Excellent for soil control and drainage |
Watering
How often should you water collard greens?
Every 2 days through the growing season, at about 700 ml per 10 litres of soil — daily in hot weather, every 4 days when it turns cool. Water in the early morning. Soaker hose or drip irrigation works best.
Too little water
- wilting leaves
- stunted growth
- bitter taste
Too much water
- yellowing lower leaves
- stunted growth
- root rot
Avoid: overhead watering (can promote disease); standing water; letting soil dry out completely.
Climate
Can you grow collard greens where you live?
No hardiness zone needed — compare your actual temperatures against the plant's own limits.
| Ideal range | 13 – 24 °C |
|---|---|
| Survives | -7 – 30 °C |
| Germinates above | 7 °C — best at 21 °C, about 7 days |
| Flowers drop | above 28 °C |
| Sunlight | 6–10 hrs/day, best 8 |
| Frost | Low sensitivity |
The flower-drop thresholds matter more than the survival ones. A plant can be perfectly alive at 30 °C and still give you nothing.
How cold is too cold for collard greens? Check your temperaturesEnter your night low and day high — see if it survives, and if it will cropTimeline
Collard Greens growing stages, day by day
Click any stage to see what's happening. Durations shift with temperature — a warm season runs roughly a quarter faster than a cool one.
Feeding
Fertiliser schedule for collard greens
Feed on the interval below, changing what you give as the plant shifts from making leaves to making fruit.
| Stage | What to use | Per 10 L | Every |
|---|
How to prepare each feed
Common mistakes
Why collard greens fails, and how to avoid it
- A container that is too small
Below 10 litres the root run is too shallow. The plant grows, flowers late, and drops whatever it sets because it cannot support the crop.
- Watering too lightly
A daily splash wets the top few centimetres and nothing else. Collard Greens wants about 700 ml per 10 litres of soil — one deep soak beats three shallow ones.
- Ignoring the flower-drop threshold
Above 28 °C flowers fall before setting. The plant can look perfectly healthy and still give you nothing — shade it through the hottest hours.
- Planting it beside Broccoli
As another brassica, it competes for the same nutrients and attracts the same pests and diseases.
Companions
What to plant with collard greens
Good neighbours
Deters common brassica pests like cabbage worms and aphids with its strong scent.
Emits a strong scent that deters spider mites, aphids, and cabbage worms.
Attracts beneficial insects like ladybugs and parasitic wasps, which prey on aphids and cabbage worms.
Roots produce a chemical that kills root-knot nematodes, and flowers repel other harmful insects.
Acts as a trap crop for aphids, drawing them away from collard greens, and can also deter cabbage worms.
Keep apart from
As another brassica, it competes for the same nutrients and attracts the same pests and diseases.
Similar to broccoli, cabbage is a brassica that will compete for resources and share common pests and diseases.
Can stunt the growth of collard greens and other brassicas.
Can stunt the growth of collard greens and other brassicas.
As a close relative, it shares many of the same pests and diseases, potentially increasing infestation pressure.
Problems
Collard Greens pests and diseases
Each lists the weather that brings it on, so you know when to start checking rather than reacting once it's established.
Cabbage Worms humidity any · temp >15
Includes imported cabbageworms, cabbage loopers, and diamondback moth larvae. They chew ragged holes in leaves, often near the center, and leave green frass.
Aphids humidity any · temp 15-25
Small, soft-bodied insects that cluster on new growth and the undersides of leaves, sucking sap and secreting sticky honeydew. Can cause distorted leaves and stunted growth.
Flea Beetles humidity dry · temp >20
Tiny, jumping beetles that chew small, round holes (shot-hole appearance) in leaves, especially on young plants. Severe infestations can stunt growth.
Clubroot humidity wet · temp 18-25
A soil-borne fungal disease causing swollen, distorted roots, stunted growth, and wilting in hot weather. Prefers acidic, wet soils.
Black Rot humidity >80% · temp 20-30
Bacterial disease causing V-shaped yellow lesions on leaf margins that turn black, with black veins. Can spread rapidly in warm, wet conditions.
Downy Mildew humidity >90% · temp 10-20
Causes yellow spots on the upper leaf surface and fuzzy gray mold on the underside. Thrives in cool, wet, humid conditions.
Alternaria Leaf Spot humidity >80% · temp 20-28
Fungal disease causing dark, concentric rings (target-like spots) on older leaves, which can merge and cause defoliation.
Harlequin Bugs humidity any · temp >20
Brightly colored, shield-shaped bugs that suck sap from leaves, causing white or yellow spots, wilting, and eventually plant death.
Slugs Snails humidity wet · temp cool
Chew irregular holes in leaves, especially on young plants, and leave silvery slime trails. Active in damp, cool conditions.
Harvest
When to harvest collard greens
First picking falls between day 60 and day 75, and the plant then keeps producing for about 90 days. Pick often — what you leave on the plant signals it to stop making more.
How to tell it's ready
- Outer leaves are large and tender
- Leaves are deep green
How much to expect
Storing it: Refrigerate unwashed leaves in a plastic bag or airtight container for up to 1 week. Wash just before use.
Questions
Collard Greens: common questions
How long does collard greens take to grow?
About 70 days from sowing to the first harvest, with picking usually starting between day 60 and day 75. It then keeps producing for roughly 90 more days. Warm weather pulls that forward; cool weather pushes it back.
What size pot does collard greens need?
At least 10 litres and 25 cm deep for one plant. A raised bed wants 20 litres of soil and 30 cm of depth.
How often should I water collard greens?
About 700 ml per 10 litres of soil, every 2 days in normal weather — daily when it is hot and every 4 days when cool. Water in the early morning.
Why is my collard greens flowering but not fruiting?
Almost always pollination. Collard Greens carries separate male and female flowers and needs pollen moved between them — without insects, nothing sets. Hand-pollinate in the morning with a male flower brushed against the centre of a female one.
What temperature does collard greens need?
It does best between 13 °C and 24 °C and survives from -7 °C to 30 °C. Seed needs soil above 7 °C to germinate, ideally around 21 °C.
Can I grow collard greens in winter?
It tolerates cold better than most, down to about -7 °C, so a sheltered spot or a cold frame will often carry it through.
How do I know when collard greens is ready to harvest?
Outer leaves are large and tender; Leaves are deep green. Once picked: refrigerate unwashed leaves in a plastic bag or airtight container for up to 1 week. wash just before use.