Clubroot is a serious disease that affects kale, broccoli, cabbage in Scotland. Here is what it looks like, the conditions it needs, and the controls that actually work.
This pest lives in the soil and lies dormant until a host is planted. A seasonal calendar would be misleading.
🌱 Plants at risk
Clubroot also affects these crops in our grow guide:
Life cycle
⚠ Soil contamination: Spores survive for up to 20 years in the soil. Once a bed is infected, it stays infected for the rest of your gardening lifetime.
Why this matters in Scotland
Arguably Scotland's most consequential brassica disease, because our soils supply exactly the two conditions it wants.
Clubroot is less prevalent in alkaline soil, and better drainage holds it back. Scotland gives it the opposite of both: naturally acidic soils and a wet climate. The resting spores then contaminate soil for up to 20 years, so this is not a season’s problem. Infect a bed and it is effectively permanent within a gardening lifetime. That combination makes prevention disproportionately valuable here.
Controls: what actually works
Every method below is graded by evidence, not by how often it gets repeated. Where a claim has been tested and failed, we say so plainly.
Lime acid soil to raise pH
On acid soils apply lime at 500g per sq m, with lighter dressings of 270g per sq m in future years. Clubroot is less prevalent in alkaline soil. The target is to lime anything below pH 6.3, working toward pH 7: broccoli 6 to 7, Brussels sprouts at least 6.5, cabbage above 6.
Improve drainage — e.g. raised beds
Grow clubroot-resistant cultivars
Cultivars with useful resistance include Brussels sprouts 'Cryptus F1' and 'Crispus F1'; calabrese 'Komodo F1' and 'Monclano F1'; cauliflower 'Clapton F1' and 'Clarify F1'; cabbages 'Cordesa F1' (savoy), 'Kalibro F1', 'Kilastor F1', 'Kilaton F1', 'Kilaxy F1', 'Kilazol F1' and 'Lodero F1' (red); and swedes 'Gowrie' and 'Marian'. All show 'some degree of resistance', not immunity.
Keep down susceptible weeds — shepherd's purse, charlock, wild radish
These are brassica-family weeds that host the disease, so they sustain spore loads between crops.
Scottish grower notes
In Scotland, clubroot risk is highest in wet ground with a low (acidic) pH — exactly the conditions common here. Improving drainage, and testing and raising soil pH, are the levers that matter most; flooding can spread it between areas.
FAS Scotland guidance (written with oilseed rape in mind, but clubroot affects all brassicas the same way).
Frequently asked questions
What should I do first if I find clubroot in my garden?
Start with lime acid soil to raise ph. After that, improve drainage — e.g. raised beds. The full list of evidenced controls is above, each graded by how much evidence supports it.
Is there a spray that works?
No. There are no amateur fungicides available for clubroot. The controls that work are cultural: the measures listed above.
Sources
4 sources, recorded with what each was used for
- RHS1: 20-year spore survival, lime rates, alkalinity link, resistant cultivar list, drainage, susceptible weeds
- RHS1: brassica liming toward pH 7 and the clubroot/alkalinity link
- RHS1: independent corroboration of 'Crispus' clubroot resistance
- FAS Scotland14: clubroot risk highest in wet, low-pH Scottish ground; drainage and pH management as key levers; flooding spreads it