This year's unusual weather means Halloween pumpkins could be on the small side, the Royal Horticultural Society said.
Gardeners trying to grow the fruit for Halloween lanterns have struggled in the face of an unusually dry spring and a cool, damp spell in late summer, to get pumpkins to grow well, the experts said.
RHS principal horticultural adviser Leigh Hunt said: "It's been a strange year. To start with, a dry start to the summer meant plants struggled to get roots into the ground and establish properly."
The conditions also allowed mildew to thrive, while a lack of high temperatures or long periods of sunshine through the summer stopped the plants developing properly.
"It's not been a really long, good growing season. By August we were getting cooler temperatures into the night, and it slows down the plant and the way the fruit develops.
"People were finding the flowers rotting off, other people were finding the fruits were coming but it was very slow, and where it got really soggy, they were getting some of the fruits rotting off."
He said that in the south west and south east people struggled in the face of damp conditions, while in the Midlands it had been dry but not sunny.
Other vegetables including tomatoes, which prefer a long, hot growing season, had not thrived, although some such as courgettes had done well.
But Mr Hunt said that the news was not all bad for people wanting to carve Halloween pumpkins, as smaller fruit would be more suitable for children to have a go at turning into lanterns.
And with orchards turning in a bumper year, there is plenty of English fruit for the traditional game of apple bobbing.