Blight is the bane of many UK gardeners, especially during wet summers or in greenhouses with poor airflow. It can wipe out a crop of tomatoes or potatoes in days — but thankfully, there are now excellent blight-resistant seed varieties that offer serious protection with minimal chemical intervention.
In this article, we’ll explain exactly what blight is, what causes it, how to treat or prevent it, and which seeds — especially tomatoes — are worth growing for a strong line of defence.
Blight is a fungal-like disease caused by Phytophthora infestans. It primarily affects potatoes and tomatoes, and is most common in damp, warm conditions — especially after periods of rain and humidity.
It spreads quickly, often appearing overnight, and can devastate a crop before you have a chance to react.
Symptoms of tomato blight:
Blight thrives when these 3 conditions align:
This is known as the Smith Period — a 48-hour window of high humidity and mild temperatures that allows blight spores to germinate and spread.
There’s no true cure once blight takes hold. Fungicides are not always effective (and many are no longer permitted for home gardeners in the UK). The best response is:
If the blight is only present on the leaves or stems, unaffected fruit is safe to eat. However:
When in doubt, discard any questionable fruit to be safe.
Both varieties are bred for UK climates and provide peace of mind in wet summers. They're ideal for outdoor beds, grow bags, or patio containers — and perfect if you've had blight before.
Tip: Blight-resistant doesn’t mean “blight-proof” — always follow good growing practices to minimise risks.