Water, shade, fertilizer, don't transplant them again.
- Water deep, then let dry out. Only water in very early morning and/or at night unless you HAVE to water in the heat of the day to prevent the plant from dying; and please know, if water gets on the leaves they'll burn and die. If watering in the sun, hold the hose down by the soil, and DON'T let it splash up. At night, this doesn't matter as much unless there's not enough airflow, which could cause blight and mold or mildew, and attract pests. Pinch off stems on peppers and tomatoes low to the ground so there's plenty of clearance. This will help with disease and some pests enormously.
- In Zone 7 you're likely in the hundreds for days upon days straight. That much sun can stress even heat-lovers like corn, tomatoes, peppers, cucumbers, squash, melons, and some flowers. Move them to a place where they will get adequate sun, but also enough shade to not die, and hopefully thrive. 6-8 hours in Zone 7 at this time of year should be more than enough; the sun not only bakes the leaves, flowers, and fruits, but the soil, and in bad cases, the roots. This is another reason why enough water is important. Mulch also traps moisture and insulates the soil, and therefore the roots, from the sun. Anything can be mulch as long as it's organic and/or non-toxic.
- As far as fertilizer, it's typically sold with a row of three numbers with dashes in between them on the front of the bag or box. Example: 4-7-2.
The first number represents nitrogen, or N. This is for vegetative growth. The higher this is, the more foliage your plant will put out, and it will often be very dark green, which means they have rich nutrients and are very healthy.
The second number represents phosphorous, or P. This is for flowering and fruiting. The higher this is, the more flowers and more fruit your plant will want to produce. This is great for almost any flower and any food-producing plant. (Not so necessary for leafy vegetables though.)
The third number represents potassium, or K. This aids in the movement of water and nutrients throughout the entirety of the plant, which is required in order for the plant to grow at all. It helps ensure nutrients make it upward to aid in photosynthesis, which is how the plant feeds itself.
Typically I use nitrogen-heavy fertilizers while the plant is young and needs to grow as big and strong as possible before flowering and/or fruiting, then when it starts putting on a lot of flowers, I use a phosphorous-heavy fertilizer to boost production. However, both fertilizers at both times must have a decent amount of potassium, because without potassium the plant will slow down, yellow, and die.
Do NOT over-fertilize - follow the instructions on whatever fertilizer you buy. Overdoing it can burn the roots and kill your plant in hours. No joke. Make sure to water it in thoroughly as well to disperse it evenly. You should see signs of the fertilizer working by the next morning. Fertilizing at night is typically best.
4. You don't need to transplant them again; as long as you change a few things they will be alright where they're at. A word of advice my mom learned the hard way; don't try to transplant anything at the beginning or middle of a hot day. Wait until the sun has mostly gone down and it drops by at least 15 degrees or more. Dig deep enough, press the soil to stabilize, and water deeply. Let the plant recover overnight. This cool period is essential for a young plant to survive transplant in summer. Check early the next morning; if you stick your finger down and it's dry, water deeply, remembering not to get water on the leaves. The first day after transplant go outside once or twice as it gets really hot and check how they're acclimating to the heat. If they're not doing well, make sure they have water and put something over them to shade them from the sun that still allows air movement; otherwise it will broil. Umbrellas are great for this. Keep them shaded all day if necessary; it's worth it, I promise. Once the plant has largely recovered and is looking lively again (this can take a few days, so do your best), fertilize as appropriate for the developmental stage the plant is at. Do not neglect to water. Then continue to support and tend to the plant as usual.
You're not doing so bad! Summer is ROUGH and it's a learning curve for everyone regardless of where they live or how much experience they have. Just do your best; there's always next year. Another trap my mom fell into: Don't stress or consider yourself a failure if everything dies or you don't get a good crop, or no crop at all. It's sad, yes, but again, there is more time. Keep what you want to do manageable and focus on learning one thing at a time. And above all: find the joy. What makes you happiest? What's your favorite part? What do you actually want to eat or smell from your garden? This a journey of self-discovery. Enjoy the process, because that's what it's there for. Don't eat to live; live to eat. You deserve it. You want to nurture and provide; embrace that, because that's a really great quality. And happy gardening!!
