As a general rule, nightly plant watering is safe as long as the leaves aren't left wet overnight and the ground isn't frozen. This applies to both indoor and outdoor plants, potted or in-ground. Where possible, water your plants early in the morning or late afternoon instead.
Seedlings should be watered once a day or every other day, depending on how much sun and heat they get. Remember that seedling roots are fairly close to the surface and they're growing in a small amount of media, so they don't need a deep soak the way larger plants do.
Night-time watering is not ideal because your plants' leaves may not be able to dry off as quickly as other times of day. Wet leaves are more susceptible to diseases. That said, water your plants the moment you notice they look wilted.
Until seeds have sprouted, keep the seed bed moist, never allowing it to dry out. Water with a fine-spray hose nozzle or watering can which will provide a fine misty spray and not wash away the soil. Water often enough (usually about once a day) so that the soil surface never dries out, but remains constantly moist.
For seeds to germinate, you need to keep the growing soil damp but not too wet. Learning how to water seedlings is pivotal for success. Many seed starters cover the container to keep soil moist until seeds germinate. Once seeds sprout, do not miss a watering.
Only water at night as a very last resort, if your plants are very thirsty and you can't wait until morning. If you must water at night, water the soil to avoid getting the plant itself wet, and use less water to avoid waterlogging.
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.
1) Plants are sensitive to temperature changes
The reason why we recommend early morning, between the times of 7am and 10am, is the temperature is not yet too hot. Personally, I water the plants I'm growing at home immediately after I wake up.
OTHER BENEFITS OF BOTTOM-WATERING
The beginning stages of germination require the surface of your seed starting mix to be moist, but once you see newly sprouted growth, it's time to ditch the topwater.
How can you prevent overwatering? The simplest solution is to only ever water your plant when the top two inches of soil feel dry (for cacti and succulents, water when the soil is fully dry). This gives your plants time to drink at a steady pace. Also make sure excess water can drain off.
Water is one of the vital elements when starting plants from seed. Too much water and your seeds will drown or rot. Too little and they will either fail to germinate or die once they do.
Plants release oxygen during the day in the presence of natural light through the process of photosynthesis. While at night, the plants uptake oxygen and release carbon dioxide, which is called respiration.
Cover Plants – Protect plants from all but the hardest freeze (28°F for five hours) by covering them with sheets, towels, blankets, cardboard or a tarp. You can also invert baskets, coolers or any container with a solid bottom over plants. Cover plants before dark to trap warmer air.
Watering indoor and outdoor potted plants at night can increase the chances of root rot. Even a little water left in mulch or soil consistently can damage the root systems, which can cause the plant to struggle to grow.
At the time of day even if there is a lot of moisture it can be absorbed by the sun but during the night time, watering allows the water that is sprinkled to stay for an extended period as there is no sun to absorb the moisture. This will surely result in fungi and bacteria.
Plants can, in fact, absorb water at night. They absorb water through their leaves and roots at night. Although, night time may not be the greatest time to water your plants. Watering at night allows the water to remain on the plant for longer periods of time, which might encourage bacterial or fungal growth.
Watering in the evening with a sprinkler or garden hose can lead to greater disease problems as the plant foliage will likely remain wet throughout the night. Mornings and evenings are excellent times to water gardens when using a drip irrigation system or soaker hose.
Most plants shut down during extreme heat, so if it is over 100 degrees, it may be best to wait to water even if your plant is stressed. Throw a damp sheet over it, or mist it lightly to bring the temperature down.
The best time to water your garden in summer is from 6 am to 10 am—before the heat of the day sets in, giving your plants plenty of time to drink up and any moisture on the leaves to dry off before nightfall. What is this? If watering in the morning isn't possible, the next best time is from 4 pm to 7 pm.
Fortunately, most tap water has low levels of chlorine that won't be directly detrimental to your plants. But if you're still concerned, simply check the smell of your tap water. If you can smell chlorine, it likely has unusually high chlorine levels.
Can you over water by bottom watering? Yes, if the plant is sitting in water too long, you can still overwater your plant through bottom watering. However, bottom watering is a more controlled method of watering your plants.