Purple sprouting broccoli (PSB) is a long-season brassica, usually sown in spring and harvested from late winter into spring.
It takes patience, but it earns its space by producing fresh spears during the late-winter and early-spring hungry gap. This guide is based on UK growing conditions, although much of the advice also applies in other cool temperate climates.
When to Sow Purple Sprouting Broccoli
For most UK growers, March to May is the main sowing window.
Early varieties can be started towards the beginning of this period, while later varieties can be sown further into spring. Later sowings can still work, but plants may go into winter smaller and crop later.
How to Grow Purple Sprouting Broccoli From Seed
Sow seeds into modules, small pots or an outdoor nursery seedbed.
Place seeds around 1–2cm deep, cover lightly and water.
Once seedlings appear:
- Keep the compost moist but not waterlogged
- Give them plenty of light
- Thin to the strongest seedling where necessary
- Pot on if they become rootbound
Modules make young plants easier to protect from slugs and other pests, while a nursery bed works well if you are growing several plants.
Seedlings are usually ready to plant out at around 10–15cm tall with several healthy leaves. Harden off plants raised under cover before moving them outside.
Planting Out Purple Sprouting Broccoli
Choose a sunny position with fertile, moisture-retentive but well-drained soil.
Before planting:
- Add well-rotted compost or manure if needed
- Firm loose ground
- Remove perennial weeds
- Avoid areas prone to winter waterlogging
Plant firmly, slightly deeper than they were growing, with the lowest leaves close to soil level. This helps anchor the plants before winter.
Water thoroughly after planting.
How Far Apart Should Purple Sprouting Broccoli Be Planted?
Around 60cm between plants is a good practical spacing for most traditional varieties.
You can plant at around 45cm where space is tight, while vigorous plants may benefit from 60–75cm or more.
How Tall Does Purple Sprouting Broccoli Grow?
Traditional varieties commonly reach around 90–120cm tall, although vigorous plants can grow larger.
That size matters when planning spacing, netting and winter support.
Does Purple Sprouting Broccoli Need Netting?
Yes. Netting is one of the most important parts of growing purple sprouting broccoli successfully.
I treat protection as essential with PSB, as I do with most brassicas.
Cabbage White Butterflies
Cabbage whites can lay eggs on unprotected leaves during summer, and the caterpillars can strip plants quickly.
Fine insect mesh is the simplest way to prevent this.
Pigeons
Pigeons become a bigger problem through autumn and winter and can badly damage mature plants when other food is scarce.
Ordinary bird netting can stop pigeons, but it will not reliably exclude butterflies. If you want one cover for both problems, fine insect mesh is the best all-round option.
Keep it:
- Secured at ground level
- Free from gaps
- Clear of the foliage where possible
- Tall enough for mature plants
Plan the structure for the final plant size rather than the small transplant you start with.
Watering, Feeding and Summer Care
Water newly planted PSB regularly until established, then during prolonged dry spells.
A layer of compost or organic mulch helps retain moisture and suppress weeds. Otherwise, summer care is mainly about keeping weeds down, checking netting and making sure plants remain firmly rooted.
What Is the Best Fertiliser for Purple Sprouting Broccoli?
Good soil matters more than constant feeding.
If the bed contains plenty of organic matter and the plants are growing strongly, additional fertiliser may not be needed.
On poorer soil, a nitrogen-rich feed during active summer growth can help build stronger plants before winter. Routine feeding through late autumn and winter is unnecessary.
Getting Purple Sprouting Broccoli Through Winter
PSB is hardy, and ordinary UK winter cold is rarely the main problem.
The bigger risks are pigeons, winter storms and waterlogged soil.
Through winter:
- Keep protection secure
- Check cages after storms
- Firm plants back into the ground if they start rocking
- Earth up around stems where useful
- Stake large plants on exposed plots
- Remove badly damaged or rotting lower leaves
- Avoid waterlogged ground
Routine fleece is generally unnecessary for established traditional varieties.
If you’re planning other crops for the colder months, the Winter Growing Guide UK covers what to sow, grow and harvest from December to February.
Does Purple Sprouting Broccoli Need Staking?
Not always, but tall plants on exposed plots often benefit from support.
Use a sturdy cane or stake and tie the main stem loosely. Earthing up around the base can also help.
The main aim is to prevent windrock, where repeated movement loosens the roots.
When to Harvest Purple Sprouting Broccoli
Most traditional PSB crops from late winter into spring, with February to April a useful general UK window.
Early varieties may start around January in mild areas, while later types can continue into spring.
How Do You Know When Purple Sprouting Broccoli Is Ready?
Harvest when the spears are well developed but the flower buds are still tight and closed.
Look for tender stems and compact purple buds before yellow flowers begin opening.
PSB does not form one large head like Calabrese, so don’t wait for it to resemble supermarket broccoli.
How to Harvest Purple Sprouting Broccoli
Start by cutting the central spear. Cut the spear with around 10–15cm of tender stem where possible.
Removing the main shoot encourages smaller side shoots to develop.
After that:
- Check plants regularly
- Harvest side shoots while the buds remain tight
- Keep picking as new shoots develop
- Stop once the shoots become too small or start flowering too quickly
A healthy plant can continue producing for several weeks.
Best Purple Sprouting Broccoli Varieties
Claret F1 AGM
This variety are vigorous and heavy cropping, making it a strong all-round choice for a traditional spring harvest.
DT Brown currently sells Claret F1 as young plants, making it a useful option if you want to skip raising the crop from seed.
Rudolph
Rudolph is a good early option and can begin cropping from around January in mild conditions.
Early Purple Sprouting
A hardy, widely available traditional variety that usually crops from late winter into spring.
Can You Grow Purple Sprouting Broccoli in Pots?
Yes, but open ground is usually easier.
Traditional PSB becomes large and top-heavy, so use a large, stable container, grow one plant per pot and be prepared to water, feed and stake it as needed.
Common Purple Sprouting Broccoli Problems
Pigeons
Winter feeding damage can be severe. Keep plants securely protected.
Cabbage White Caterpillars
Fine insect mesh is the simplest prevention. If plants are uncovered, check leaves regularly for eggs and caterpillars.
Windrock
Firm loose plants back into the soil and stake exposed specimens where needed.
Clubroot
Clubroot causes swollen roots and weak or stunted growth.
It is often worse in wet, acidic soils. Improving drainage and liming acidic ground can reduce the severity, but neither is a cure.
Crop rotation can reduce disease pressure, but clubroot can remain in contaminated soil for many years.
Why Is My Purple Sprouting Broccoli Not Sprouting?
Often, the plant simply isn’t ready yet.
Other possible causes include:
- A later-cropping variety
- Late sowing
- Small plants going into winter
- Summer drought
- Heavy pest damage
- Root damage or disease
- Colder local conditions
A healthy leafy plant has not necessarily failed just because it has not produced spears in January or February.
What to Do After Harvest
Keep picking while worthwhile side shoots continue to form, then remove the plant once cropping tails off.
Healthy material can be composted. Do not compost clubroot-infected roots in a normal home compost heap.
Because PSB can occupy a bed well into spring, it is worth planning the next crop before clearing it.
Not sure what to plant after your broccoli? Open the BYF Allotment Planner and see what can go into the space next.
FAQs
Traditional overwintering varieties take many months. Plants sown in spring or early summer usually remain in the ground through winter before cropping the following late winter or spring.
No. Traditional PSB is normally grown as an overwintering biennial crop and removed after its main spring harvest.
Avoid cutting the whole plant back during growth. Harvest the central spear first, then continue cutting the smaller side shoots as they develop.
Final Takeaway
Give purple sprouting broccoli plenty of room, keep it protected from pigeons and caterpillars, and secure large plants before winter.
It occupies the ground for a long time, but the payoff is a fresh crop of tender spears at the end of winter and into spring.
