|Heat stressed tomatoes.|
12 May, 2014
Surfing the Heat Wave
Looks grim doesn't it? It looks like a week of very high temperatures ahead for Southern California. It will affect our gardening and seed saving in a multitude of ways. I've seen tomatoes turn white, becoming inedible just before they would have been ripe. Sunstroke. And that's just one of the sad consequences of this heat.
Tomatoes don't fertilize well above 85° - the pollen is heat sensitive. Some folks have said to me they don't see any bees at their tomatoes and think that's why they have no fruit. Not true. Bees can, but usually don't pollinate tomatoes. Tomatoes almost ALWAYS self-fertilize - they have both male and female equipment in the flower and they will do the deed before the flower is even open. The exception to self pollination are those varieties that are "potato leafed." Not all of them will, but many of them can be pollinated by bees. You can tell those that can be pollinated by bees because the sexual flower parts extend beyond the green sepals keeping the young blossom closed. With the stamens and pistil sticking out beyond the closed flower, bees can effectively pollinate the flower and that might include crossing. However, on the scale of things to worry about, accidental tomato crosses are somewhere up there with Godzilla sightings. Outside of Tokyo.
Shade cloth will help - especially if this heat wave doesn't hang around for more than a week - try to imagine it's the same as a cold snap. If you protect your tomatoes from too much cold, when the cold has passed, you remove the things you were using to keep them alive. Same thing here. Shade cloth - try to protect primarily from the intense noon to three PM heat - that's the most damaging. Add extra water for the roots. Be prepared for plants to wilt in the day but revive over night. Don't freak out too much. Yes, it's not ideal, but wilting is a plant's defense against losing too much water in high heat. The wilted plant hangs onto more water than a rigid plant could.
Watering is much more effective in the evening or the early morning. Of the two, evening is the best because there is more time for the water to get into the ground and not be vaporized off into the atmosphere. If you have bad mildew problems, morning is your best bet because it will foster less mildew.
Remember, you ARE doing extra watering, but we ARE also in a drought. You see the contradiction in what we need to do? This is just an inkling of what growers of food will have to contend with more global climate change. We will be faced with two choices and both of them will be bad.
Wear your hat, long sleeved shirts and long pants. I know, I've heard it all before, but this is not Grandma's sun anymore kiddos! Protect your skin. Try not to do a lot in the middle of these hot days. Get out there early or leave it until the evening. I don't need any sunstroked readers - readers are too hard to get already. I gotta keep you alive!