Growing adequate lettuce throughout the year

 Hello Ann, welcome to the forum,

You are not alone in this difficulty of lettuce germination in summer, and I think there are two factors. First that lettuce germinates better in cooler temperatures, as you are experiencing. However I find that seed does germinate, and then grows fine, from sowings in July and August when seed trays are placed underneath the greenhouse staging, in temperatures of around 15-20C. A July sowing is worth making, to take over from May sowings which may result in some varieties flowering by August if it has been a hot summer.

Also I think there is a question of seed viability.  Whether seed we buy is older than it used to be or just less dynamic, I find a greater difference between most (not all) seed I buy and the seed I save here, which shoots out of the compost compared to growth of bought seed which often seems reluctant and hesitant, even though it does germinate. I have noticed the same thing with squash and courgettes.

Some of my better seeds last year were from http://www.stormy-hall-seeds.co.uk, http://www.realseeds.co.uk, http://www.OrganicCatalogue.com and Mr Fothergills!