"If the top layer feels dry, it is time to water. If the soil is still moist, no watering is needed that day." Droopy tomato plants can be a sign of dry soil or drought—but they're not a reliable indicator of whether your plant needs water. "Tomatoes will wilt or droop during drought or high heat," says Mercer.
You can safely stop watering your tomatoes. Watering twice (sometimes thrice) a week is the general recommendation for mature plants, I believe (so, if it rains sufficiently twice a week, I think you're good with that, and/or a possible hose-watering once a week, too).
Consistent Watering: During the early stages of growth and fruit development, tomatoes need consistent moisture. Aim to water deeply but infrequently to encourage deep root growth. This typically means watering once every 1-2 weeks, depending on rainfall and temperature.
Overwatering generally makes the plant look almost like it's rotting, as in drooping and turning soggy brown. My guess is it is having Nitrogen problems. Any type of vegetable fertilizer you buy at the store should work fine.
Leaves Turning Bright Yellow or Mushy Stems
This is usually a sign of overwatering, either caused by watering your plant before it's ready or if your plant is in too low of light. When plants sit in waterlogged soil, their roots can't get enough oxygen, leading to root damage which manifests as yellow leaves.
Overwatering tomatoes can lead to yellow and spotted leaves, while underwatering results in wilt and diseased fruit.
Tomato plants need about 1 to 2 inches of water per week. However, your plants may need more or less water throughout the season, depending on your area's hot weather and rainfall.
Vine crops are heavy water feeders, so you should constantly check soil moisture. Cucumbers need about one inch of water from rainfall or irrigation each week during the growing season. Always soak the soil thoroughly when watering. Water sandy soils more often, but with lower amounts applied at any one time.
The advantage in removing the lower leaves is that the plants energies go into producing fruit rather than a lot of foliage. Also the lower leaves tend to get powdery mildew so it is good to remove them to stop disease spreading.
Some growers prefer to use a high-phosphorus fertilizer, indicated by a larger middle number. You can also keep things simple with a fertilizer especially formulated for tomatoes – usually with a ratio like 3-4-6 or 4-7-10. Most importantly, don't over-fertilize. Too little fertilizer is always better than too much.
Try to plant tomatoes in a different spot every year, rotating through your garden space every three to four years. Planting them in the same place allows disease pathogens that are specific to tomatoes to build up in the soil. By moving them around in the garden each year, you can break up the disease cycle.
Tomato plants recover quickly from overwatering, usually in one to two weeks with treatment. How often should you water tomatoes? In the garden, water tomato plants deeply at the soil level once a week or twice weekly during hot weather depending on rainfall.
What's most important is how the plant looks in the evening, after sunset. However, don't water until the next morning. If you water at night, the already wetter conditions and low temperatures can promote disease.
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.
Drip irrigation has emerged as one of the most efficient methods for irrigating tomatoes.
This depends on the plant types, garden light conditions, and weather. Plants in shaded areas may last longer without water compared to those in full sun. Container and window box plants can dry out in a day, whereas many houseplants can manage with one watering per week or less.
Remove blossoms and small fruit to encourage ripening of the remaining tomatoes. Reduce or stop watering about mid- to late-August to stress the plant and encourage ripening.
The good news is that most plants will bounce back between 7-14 days if they're given proper care (which includes rehydration). If this isn't possible because major damage was done or little healthy root system exists then expect about 2 weeks until improvement can be seen.
Plants may wilt badly when soils are dry, but will revive rapidly when they are watered. A thorough watering once a week during hot, dry weather should be sufficient. Apply water directly to the soil around the base of the plants with a garden or soaker hose.
Prune off yellow or brown leaves and stems.
They won't grow back and no longer contribute to photosynthesis. This will also help your plant to grow again.
When you see an entirely yellow leaf, you should remove it from your plant using a sterile cutting tool. Removing the leaf will let the plant focus its nutrients on healthy leaves. A yellow leaf has lost its chlorophyll (pigment) and it can't turn green again even after you correct the problem.
WATERING ISSUES CAUSE YELLOW TOMATO LEAVES
Too much water is a common problem that can lead to root rot. Too little water can also cause problems for tomatoes. Before the yellow leaves stand out due to incorrect watering, you may notice wilting and brown edges.