Mildew Resistant Courgette Varieties (UK)

Courgettes are one of the UK’s most popular summer crops—but if you’ve grown them before, you’ve likely run into a common frustration: powdery mildew. This white, dusty fungal disease can quickly take over plants by late summer, affecting leaves, yields, and overall plant health. Fortunately, modern breeding has introduced a range of mildew-resistant courgette varieties that offer longer cropping, cleaner foliage, and fewer issues.

In this guide, we’ll explain what mildew is, how it develops, how to treat and prevent it, and which courgette seeds are best for mildew resistance in UK gardens.

What Is Powdery Mildew?

Powdery mildew is a fungal disease caused by airborne spores that thrive in warm, dry days with cool, humid nights—conditions all too common in the British summer.

You’ll know it by:

• White, powdery patches on upper leaf surfaces
• Leaves turning yellow, dry, and brittle
• Reduced fruiting and eventual plant collapse if untreated

It often appears later in the season (July–September), but prevention starts much earlier.

What Causes Mildew on Courgettes?

Mildew is encouraged by:

• Overcrowding: Poor airflow between plants traps humidity
• Drought stress: Dry roots = stressed plants = more vulnerable
• Splashing water on leaves: Helps spores settle and spread
• Excess nitrogen feeding: Encourages weak, soft leaf growth

How to Prevent Powdery Mildew

• Choose mildew-resistant varieties (see below!)
• Space plants generously to promote airflow
• Water at the base, not over the foliage
• Mulch around plants to reduce moisture fluctuations
• Feed balanced nutrients — not too much nitrogen
• Prune lower leaves or large outer leaves to improve ventilation

How to Treat Powdery Mildew

If you spot the signs early, you can reduce its spread:

• Remove infected leaves — dispose of them in the bin, not compost
• Spray with a natural treatment like:
• 1 part milk to 9 parts water
• Or a bicarbonate of soda mix (1 tsp per litre + drop of washing-up liquid)
• Improve ventilation or thin out heavy leaf growth

Note: These treatments don’t cure mildew — they only slow it down. Once it’s widespread, it’s usually best to remove the plant.

Can You Eat Courgettes from a Mildewed Plant?

Yes — as long as the fruit is unaffected, you can eat courgettes from a plant with mildew.

• Pick early and often — fruits may develop faster as the plant declines
• Avoid fruits that feel soft, spotted, or have mildew on the skin itself
• Harvesting regularly helps reduce plant stress and prolongs useable yield

What to Do With Courgette Plants Once Mildew Sets In

1. Harvest any usable fruit
2. Cut down the plant at the base
3. Do not compost infected leaves
4. Dispose of affected material in the general waste or council green bin
5. Clean any tools, pots, or support frames used with the plant

Rotating crops the following year and avoiding cucurbit family plants in the same spot will help reduce future issues.

Best Mildew-Resistant Courgette Varieties

Modern courgette breeding has made huge strides in disease resistance. These varieties have been developed specifically to resist powdery mildew and perform better in UK conditions.

Note: Even resistant varieties can show some signs of mildew in high-pressure years — but they’ll stay productive and healthy far longer than standard types.