The "Batavia" types are supposed to resist summer heat well. I haven't tried them yet, but believe I have a packet of one or two to sow this season.

In fact, I could be wrong, but isn't "Four Seasons" a Batavia type?

I tried "4 Seasons" last year for the 1st time and it is now my favorite lettuce! Up early in the spring and lasts though the hot summer.I love it!I love the color also,reddish on the outside and green leaves inside.I also like "Nevada" for summer,takes a long time to bolt.

That's nice that you say four seasons does well in heat.... I'd love to try it.... one source said it doesn't color up in summer (only in cool weather) is that true?

Mine is always colored.

I have grown lettuce all summer in partial shade and it does great. My favorite is the cut and come again type. Particularly, Renee's Garden's Ceasar Salad Duo.

Here is a link that might be useful: Renee's Garden

Well the reason lettuce does well in part shade and does not bolt in hot weather is most lettuce is day length sensitive once it reaches a certain maturity, which cause it to bolt.

Four Seasons is a butterhead lettuce and in my experience, does not do particularly well in the summer in that it has moderate resistance to bolting. It is not awful, but seems to prefer spring & fall a bit better & certainly colors up better in the fall (it is just beautiful).

Check the back of seed packs; 'most of them will say how likely they are to bolt.

Bill McKay