Consistent watering – Bottom watering provides an even distribution of moisture throughout the entire mass of soil. Top watering can result in dry spots, but this isn't an issue when water is slowly absorbed from the bottom. You can be assured your plants are getting enough water.
Watering from the top down can help flush excess salts and mineral deposits to the bottom of the pot and eventually out of the drainage holes. Constantly bottom watering will keep these salts and minerals in the potting mix, so top watering can help keep the root system of your plants healthier.
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.
All you need to do is set the potted plant (be sure it has drainage holes) into the bathtub, sink, or another container that's filled with a couple inches of water. After 15 to 20 minutes, the plant will have absorbed the exact amount it needs—never too little or too much.
These plants are prime candidates for bottom watering: Plants with hairy or fuzzy leaves, such as African violets, or plants that don't like getting their leaves wet, such as snake plants, Philodendron verrucosum, and P. micans.
What's the Most Efficient Way to Water Plants? DO direct water at the base of a plant and avoid wetting foliage, which invites fungus. Also, you'll lose less water to evaporation and, since you're applying water directly to the root zone, the water will be readily available to the plant roots.
Watering is a critical part of plant care, and bottom watering can help prevent yucky things like fungus gnats.
The best time to water is early in the morning when it's still cool, which preps the plants for a hot day, but that's not always easy to accomplish with a busy schedule. The second-best time is late in the afternoon or early evening.
The downside of bottom watering plants
In terms of plant health, there aren't a lot of drawbacks to watering plants from the bottom. However, one consideration would be that continual bottom watering could lead to a build up of minerals and excess salts in the growing medium, especially if you're using tap water.
Bottom watering prevents accidental leaf splashes or water retention. Some plants won't respond well to this method if they have sensitive roots and can't tolerate higher levels of salt and mineral buildup. This is the main issue with bottom watering, as the soil doesn't have a way to dispose of these materials.
Bottom-watering, sometimes called reverse watering, is when you place a plant in a bowl of water, allowing the soil and roots to soak water from the bottom up. (Naturally, your pot needs to have drainage holes for this to work.)
The best way to give your plants a drink is to put water on the soil near the base of the plant with a hose or watering can. Don't dump water on the plants from above. And do not use overhead sprinklers.
How to Prevent Fungus Gnats. Neither fungus gnats nor their larvae can survive in dry soil, so let your soil dry out completely between watering as often as possible.
Bottom watering doesn't flood the soil surface, so the topsoil tends to dry out faster using this method. It would be better not to allow water to penetrate all the way to the surface; but, even so, bottom watering will still help reduce your gnat population.
There is a handful that can keep gnats at bay, including geraniums, lemon thyme, lavender, and Mexican marigold.
When a plant is first becoming overwatered, leaves turn yellow. If soil doesn't have a chance to dry out before you water again, leaves start to wilt. When overwatering is the problem, wilted leaves are soft and limp. (If too little water is the issue, wilted leaves are dry and crispy.)
If the soil is wet, it's overwatered - if it's dry, it's underwatered. Browning edges: Another symptom that can go both ways. Determine which by feeling the leaf showing browning: if it feels crispy and light, it is underwatered. If it feels soft and limp, it is overwatered.
Yellow leaves, mushy or loose bark on the plant stems and molds that appear on the top of the soil are also indicators of overwatering.
How Often to Bottom Water Plants. You should bottom water your plant when your plant needs to be watered. Obviously, this varies wildly from plant to plant and can also depend on the time of year, your plant's light conditions, and environmental humidity levels.
Plants that like coffee grounds also respond well to watering with coffee liquid. However, it is a fairly strong fertilizer, so this watering should not be done more than once a week. To prepare the mixture, boil the coffee and pour one and a half times as much water.
When plants have too little water, leaves turn brown and wilt. This also occurs when plants have too much water. The biggest difference between the two is that too little water will result in your plant's leaves feeling dry and crispy to the touch while too much water results in soft and limp leaves.