During May and June, garden plants will use about one inch of water each week. In July, August, and September, they require about two inches of water per week for best growth. It normally takes this amount of watering per week to maintain production if no rain falls.
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.
This method encourages the plants' roots to reach deeply for residual water, even when the surface of the soil appears dry. The standard rule of thumb is to give your flowers and vegetables the equivalent of at 1 inch of water per week (and as much as double that amount in the peak of summer).
Quick facts. Water your garden so that your plants always have enough moisture. On sandy, well-drained soil, you may need to water twice a week. For soils that hold moisture, such as heavier clay soils, or loamy soils rich in organic matter, watering once a week is fine.
During really hot weather, water your vegetables at least two to three times a week.
When. Hands down, the best time of day to water is early in the morning. Watering during the day can increase risk of disease. If you can't water early in the morning, water late in the evening, especially before days forecasted to have dangerously high temps.
During hot weather, water your tomato plants daily, but give them less volume. You can return to twice-weekly deep soakings when the temperature breaks. And when weather is hot, consider providing relief for plants with shade cloth, particularly from 10 AM to 2 PM during the heat of the day.
Water newly planted tomatoes well to make sure soil is moist and ideal for growing. Early in the growing season, watering plants daily in the morning. As temperatures increase, you might need to water tomato plants twice a day. Garden tomatoes typically require 1-2 inches of water a week.
How Long To Water Your Garden. Adjust your watering schedule based on specific plant needs and the seasons. In the summer, I either water with a slow drip for 1 hour every three days or 30 minutes every day. In winter, I might go a month or more without watering.
It is ideal to water lawns about one inch of water per week. To determine how long you need to water to get one inch, place a plastic container in your yard and set a timer. On average, it will take 30 minutes to get a half inch of water. So, 20 minutes, three times per week will give a lawn about an inch of water.
As the weather heats up and plants reach full size, you may need to water containers (and especially hanging baskets) twice a day.
Soil that contains a lot of sand doesn't hold water well and dries quickly. Because of this, tomato plants growing in sandy soil may need to be watered more often, about every three or four days. Clay soil, on the other hand, holds water well. Plants growing in clay soil usually only need to be watered once a week.
When To Stop Watering Plants in Fall. When the air and soil temperatures consistently fall below 40 F, it's time to stop watering. The ground can't absorb water once the top few inches freeze. Continue to water your plants up until this point so they're as well-hydrated as possible going into winter.
Avoid watering when temperatures are below 40°F or when sustained freezing temperatures are expected within 24 hours as this water will freeze and not be available to the plants.
The best time to water plants is in the morning or evening.
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.
So, how hot IS too hot for plants? The general answer is around 90 degrees F, with some exceptions to the rule.
If your plants are in the ground (versus a pot), the general rule is that plants need one inch of water per week. However, this does NOT mean watering one time per week. That doesn't usually do the job. Plants do best when watered deeply about three times a week, factoring in the rain.
If your plants have yellowing leaves and old leaves, as well as new leaves that are falling at the same accelerated rate, you are overwatering.
Although a vegetable garden can usually survive a week without water, this number can vary anywhere from as little 2 days, up to as long as 14 days.
Watering in the morning is ideal from a water efficiency standpoint (less evaporation/water loss), and it also gives the foliage plenty of time to dry out (not a problem if you're using drip irrigation). Overhead irrigation of tomato plants late in the evening or at night is a no-no.
The signs of overwatering tomato plants are yellow, blistered or wilting leaves. Stems may turn yellow, too. To check if you are overwater, put your finger into the soil to assess how wet it is. If it feels boggy, especially after a dry day, your tomato plants are most definitely overwatered.
In most areas, watering tomato plants once a day is sufficient. If it rained recently, you could water every other day, and during periods when the temperature is higher than 90℉, you might need to water twice. The best thing to do is start by watering once per day and see how your plants do.
Keep plants watered
Make sure your tomatoes are getting more than their fair share. Don't forget – their transpiration rate is up. They're trying to survive. When temperatures are extremely high (consistently above 90° F during the day), water plants at once, maybe two times every day.
When daytime temperatures are up in the 90s and nights are in the 70s or warmer, tomato plants may keep on blooming, but the flowers often fall off and fruit does not set. Growing tomato plants in hot weather is not necessarily difficult, but may not yield any edibles until it cools off.