During extremely hot weather (daytime temperatures above 90F and nighttime temperatures above 70F), try to water daily or every other day. In a 10x10-foot garden, this would mean giving your plants 8 to 9 gallons of water each day.
Usually when the first inch (2.5 cm.) or so of soil is dry, it's a good indication that watering is needed. In summer, watering outdoor potted plants is necessary daily (and even twice a day) for most species, especially when temperatures reach over 85 degrees F. (29 C.).
Trees, shrubs, perennials and most of the “permanent landscape” are fine when gardeners go away for a week or two of summer vacation. Potted plants and hanging baskets are more of a concern. These can wilt after just a day or two without water, especially in a hot, sunny spot and especially when recently planted.
Overwatering will weaken your plants, especially during the summer since their roots are close to the surface where they become hot and dry out much more quickly.
Watering every day or every two days doesn't matter nearly as much as consistent watering. Make a schedule and stick to it. If you notice that plants look ailing or dry, it is a sign that your schedule needs to be amended.
Avoid creating a routine of watering at the same time every day or every week. Instead, get in the habit of paying attention to the soil and the weather so you can water when the plants really need it. Containers need frequent watering.
Morning watering is actually preferable to evening watering as the plant has time to dry before the sun goes down. At night, water tends to rest in the soil, around the roots, and on the foliage, which encourages rot, fungal growth, and insects.
The general answer is around 90 degrees F, with some exceptions to the rule. This means that when temps rise above 90 and remain there for a lengthy spell: Leaves wilt. Water evaporates into the atmosphere more quickly in high heat, draining a plant's reserves.
Avoid Overwatering Tomatoes in Summer Weather
Tomato plants need an inch or two of water a week, and a deep soaking is better than a little water every day.
Overwatering means yellowing leaves, a general feeling of flop (science calls it wilting!), fuzzy soil, and a pot that feels like it could double as a weight. Underwatering shows itself with crispy leaves, that same sad droop, and bone-dry soil.
Mornings and evenings are excellent times to water gardens when using a drip irrigation system or soaker hose. Watering in the evening isn't a problem as these methods don't wet plant foliage.
Deep watering entails watering at a slow pace for long enough that the water soaks deep into the soil, where the roots are. Often this means watering for 30-60 minutes at a time, 2-3 times each week, until plants are established.
Most established plants will not be too affected by burn from watering when it is sunny. But best practice is to avoid the leaves and water just the soil, both for conservation and for disease management.
Outdoor plants are a great addition to any home or patio area. Figuring out the perfect balance of water to help keep them healthy and looking great is a must. Misting your outdoor plants is a great way to ensure you get enough moisture without overwatering them and without underwatering them.
In general avoid watering plants when temperatures are below 40 F (4 C), unless your goal is to protect the plant from imminent frost injury using water as a protectant.
During extremely hot weather (daytime temperatures above 90F and nighttime temperatures above 70F), try to water daily or every other day. In a 10x10-foot garden, this would mean giving your plants 8 to 9 gallons of water each day.
Yellow leaves and brown spots on tomato plants are most commonly caused by early tomato blight. Once found, early blight can be managed by regularly removing affected foliage from your garden.
When high heat lingers with days above 100°F and nights over 80°F, most tomato ripening stops altogether. Fruit left on plants may have some color on the outside, but may still be green inside.
It can take anywhere from a couple of days to a couple of months for stressed plants to recover. Recovery time depends on the amount of damage that the heat caused to the plant. If a stressed plant is completely neglected during a heatwave, it can take several months or even be impossible to revive it.
The general rule of thumb is that most plants freeze when temperatures remain at 28°F for five hours. Of course, there are exceptions to this rule. Seedlings, with their tender new leaves, often give up the ghost when temperatures dip to 32-33°F. Tropical plants have differing low-temperature thresholds.
Turn your hose on a slow trickle and place it 4-6” from the base of the plant. Let the hose run between 10-30 minutes, depending on the size of the root ball. Deep soaking is the best way to water your new plants. Deep soaking of a plant in its first year can be broken down into 5 phases.
Water plants early or late in the day
Watering in the middle of the day, particularly overhead watering from sprinklers, is inefficient. Some water is lost through evaporation, which is wasteful. It's also bad for your plants.
Most plants need about 1 inch of water per week. So if you haven't received an inch of rain, then you'll need to give your plants a drink. Even if you have received rain, it's still a good idea to check the moisture level in your soil to see if your garden needs additional water.