University of Maryland Extension: Garden Q&A
Q: My tomatoes look perfect on the outside but, when I go to eat them, they have white hard areas just under the skin and even inside along the “chamber walls” down to the core. It’s not the hard white spots that stink bugs make. So what’s going on?
A: White “corky” tissue in the outer wall of the tomato is caused by high temperatures during the ripening period. Some varieties are more prone to this heat-triggered corkiness than others.
Try to maintain even moisture to keep your tomato plants’ roots cool. Mulch can aid in this. Give them a cooling shower on a blazing hot day.
Tomatoes in containers or raised beds are hotter than in-ground plants. If possible, move pots so the plants get some shade in the hottest part of the day.
Don’t over-prune your tomato so that leaves aren’t cooling the plant. Do a soil test to be sure nutrient levels are adequate.
Q: Last night we ate a wonderful watermelon. Can I save the seeds to grow next year?
A: You can only save seed from open-pollinated cultivars—not from hybrids, including all seedless cultivars.
Wash seed with water to remove the pulp. If pulp clings to the seeds, you can ferment the seeds in water at room temperature for 2-3 days and it should wash off more easily. Pat dry and spread in a single layer on a clean, dry surface for 3-5 days until thoroughly dry. You can store them in a lidded jar.
Keep in a cool (not chilled), dark, dry place. They should be good for years. If there were other watermelon varieties growing near your special one or it is a hybrid, your future watermelons may not be true to the desired cultivar.