Tomatoes staying green all summer? We may have some solutions, the reason your tomatoes aren't ripening..
Had trouble getting your tomatoes to ripen? Do loads of plump green fruit hang on your tomato vines at the end of the season? We've had this problem the last couple of summers too.
The common misconception is that tomatoes love hot weather, and the hotter the better. According to Purdue University though, when daytime temperatures stay consistently over 85 degrees, most tomato varieties have a hard time producing lycopene and carotene, the pigments responsible for the oranges and reds of fully ripe tomatoes. Though there can be other causes of perpetually-green tomato crops, such as nutrient imbalances, here are some ideas for coping with unripe tomatoes when heat is the culprit.
1. Placement: If you have a home garden, choose naturally cooler microclimates around your home for tomatoes. I'm not talking about shade, tomatoes need 7-10 hours of full sun a day, but you can choose not to plant them near south-facing brick walls which heat up terrifically on hot sunny afternoons. Container gardens and border gardens near hard surfaces, ie. asphalt, driveways, stonework, may heat up more than is desirable as well.
2. Not pruning: Many tomato growers advocate pruning tomato vines, as you would a fruit tree, for increased yields. In some situations and with some tomato varieties this works to boost yields, but if your summer days are consistently over 85, pruning can make your tomatoes less productive. Shade from leafy vines may reduces the temperature for the ripening tomato fruit, and those couple of degrees may make all the difference.
3. Make use of shade: While tomatoes need 7-10 hours of direct sun a day to perform well, late afternoon shade can reduce the temperature at the hottest time of day. Situating you tomatoes so they still get a full-days light and some afternoon shade is as simple as planting them on the east side of a fence or hedgerow.
4. Rethink companion planting: We have recently taken to planting our tomatoes in the row on the east side of our corn patches. This gives the tomatoes the right amount shade at the right time, late afternoon.
5. Choose the right varieties: Tomatoes vary by variety on their ability to cope with extreme temps. Because we consistently have weeks at a time over 95 degrees, we have been on the hunt for heat-tolerant tomato varieties that ripen during our hot summers, not waiting until temps cool a bit in fall. This package includes those tomatoes and is a great value!