But lawnmower sales were up 42 per cent as the grass grew and overall growth was five per cent in the UK thanks to good sales of paint and wallpaper.
But cutting the prices on horticultural products to clear stocks hit B&Q margins.
Group sales rose 3.7 per cent in the 10-week period, the bulk of its second quarter, while like-for-like sales – those from stores open for a year or more – fell 0.4 per cent.
This represented a recovery from its first quarter, when like-for-like sales had fallen 4.8 per.
Parent company Kingfisher chief executive Ian Cheshire said:
"The unprecedented wet weather across northern Europe has continued throughout our second quarter so far, clearly impacting footfall and consumer demand for outdoor and seasonal products.
"However, additional marketing and promotional activity helped encourage customers to switch some of their activity to internal repairs and projects, partially offsetting the weather related weakness, particularly in the UK. We also took the necessary promotional action to clear horticultural stocks."
B&Q said sourcing its own products was helping margins.
In the UK, like-for-like sales — from B&Q, Screwfix and the Eco initiative — grew 1.1 per cent in the 10-week period.