The wilting of leaves on your patio can be downright operatic. You have seen them struggle from seed, or maybe from a little seedling, watching the seedling push out of the bits of dirt with tiny might. You watched the leaves grow, you picked off aphids from bright green tight leaves. You would not SHUT UP about your new garden and possibly, let's be honest, made some friends take a step back from your enthusiasm about Smart Pots. Then the days heat up, you're wearing shorts again, and the air hangs heavy with the expectation of BBQs and songs having to do with Selena Gomez. And your plants are wilting.
You helplessly lay your palm out and the leaves are almost filmy and hot to the touch. You carefully pull your palm away, fearing your own touching of the plant will make it worse. And the only thing you can do is watch as it endures the bright heat of the sun, and count down to sunset, when temperatures will at least be just the slightest bit cool.
I live in the Valley.
The San Fernando Valley is a tough place to grow plants because it's hotter than other areas, especially in the later part of the day. Late afternoon sun can be a killer. If you happen to grow your plants in late sunlight, which means your outside area faces west and gets its light later, now is an especially important time to take care of your plants.
You can tell if your plants are heat stressed if they have burned leaves or it they have leaves that are wilted or curling up. It's important to make sure this doesn't happen too often (or, at all) because a damaged cell structure in a leaf doesn't go back to the way it originally was and you have to rely on new growth to restore the plant, which takes a long time and thusly should be avoided.
Ask your person at the local nursery if he/she'd recommend a fertilizer with phosphate in it so your thick-stalked/stemmed vegetable plants won't collapse in on themselves. However, it's also important to make sure you're not giving the plants too much fertilizer, as excess nitrogen will make leaves yellow, which resembles heat stress.
If plants are at risk of being damaged by the heat, find a shaded area or take them inside during the afternoon. If this is a frequent occurrence, consider changing where you have the plants. If you have an area of the patio that gets more morning sun than late afternoon sun, put the plants there. So basically, don't have my patio because that is exactly this.
If no space exists on your patio, consider other areas where you live -- perhaps a side yard. You may even ask your landlord if he/she'd be open to you having a few of your plants in places around the property that aren't formally "yours."
Also, make sure to regularly check if your plants are thirsty as they will be needing more water the hotter it gets. This is why watering schedules aren't as good as efficient checking because plants' water needs change by season. As mentioned before, a quick way to check if a plant needs water is by simply sticking your finger down into the soil. If it's dry past your first knuckle, water it. If your plants need water, make sure to water them in the morning when outside temperatures are still cool. This will help with evaporation. And always make sure your plants are sufficiently watered, sometimes they might need more than usual on particularly hot days. Water as usual, then check to make sure the plant is absorbing the water. If the water comes right out the drainage holes, or if the water bubbles up on the surface, the soil is very dry and has bigger water needs. To prevent your plants drying out, make sure you have enough mulch on top of your soil. This will help retain moisture and will help keep the soil cool.
However, it's just as important not to over-water your plants when the temperature heats up, as signs of over watering can look a lot like heat stress. If your plant's leaves are yellow or if the plant looks like it's experiencing heat stress but the soil is moist, more water unfortunately will not help.
There are also some things you'll be able to do with the pots themselves to beat the heat. If your pots get too hot, the roots that touch the walls of the pot will die. If you have pots you can buy multiples of, consider doubling up the pots and putting a water bottle or something smaller in the bottom of the outer pot to help with air-flow. Also check the color of your pots. Although black plastic pots are plentiful and they are the easiest to pick up for free, if you have black pots, your plants roots might be suffering from heat. Remember how the color black absorbs heat? That's this science. Consider painting your pots a lighter earthy color, and also consider alternatives to plastic, 'cause who knows what kind of stuff is in that pot?
Summer heat can be thoroughly discouraging for growing healthy plants, but it's helpful to remind ourselves (me, it's helpful to remind me) that having a green thumb just means having knowledge and patience, which are both good things to have anyway. And one of the best things about being a gardener is how many of the lessons you learn in the garden are applicable outside the garden.
Although if this were a real opera, your wilted plants will have disappointed your lover and then someone would throw someone off a bridge. So, I guess things could be worse.