“Golden Jubilee is a heirloom breed, so, I believe these plants from seeds I collected should “grow true”, correct?”
Saving seeds from Heirloom plants (also called, ‘Open Pollinated’) gives you better success than saving seeds from hybrid varieties, which will revert back to the male or the female plant used for hybridizing. You’ll still get seeds, but with only half the qualities from the hybrid.
And, you can still get some cross-pollination with Heirlooms unless you are using cages or row covers over your plants to keep the bees and other insects from going from one tomato plant to another and pollinating everything in between.
I found good info here on the subject:
https://laidbackgardener.blog/2017/06/03/how-to-keep-vegetables-from-cross-pollinating/
Keep saving seeds long enough for a variety and you’ll end up with a landrace too — https://en.wikipedia.org/wiki/Landrace
Very adapted to your particular local soil and climate.
Noted! Thanks!
Highs here 78-82 deg. F the next several days, lows from 55 deg. F to 67 deg. F: Too warm for my lettuce even if out of afternoon sunlight?