Bottom watering is okay for smaller 4–6-inch plants, but we don't recommend this for larger plants. The time it would take to soak the roots in a larger potted container and get the full capillary action to the top of the soil may be too long.
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.
After 15 to 20 minutes, the plant will have absorbed the exact amount it needs—never too little or too much. There are some other benefits of bottom watering plants, too. One being that it's great for plants that develop root rot quickly.
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.
This could lead to overwatering unless you leave the pot in the water for long enough. But then the soil might have a hard time draining, which can mean your plant is sitting in soggy soil for too long. Not good! With a well-draining pot and aerated soil, overwatering shouldn't be an issue when bottom watering.
We should water the roots so that the plant grows healthy.
However, bottom watering is a more controlled method of watering your plants. By remembering to check your plant every ten minutes or so while it's sitting in water, you can significantly reduce your chances of overwatering and causing root rot.
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.)
Bottom watering is a great way for your plants to absorb only the amount of water they need. This can be done one-on-one with a single plant, or it can be done with multiple plants at once, depending on your container. If you're doing multiple plants with one container, do make sure they are all healthy.
Soaking the soil to a depth of 5 to 6 inches encourages plants to grow deeper roots, which in the long run will make for a healthier garden. DON'T water lightly and often, which promotes shallow root growth.
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.
Water Slowly
If the soil surface is dry, water may puddle or run off and not be absorbed. The solution is to start slowly and gradually build up to a thorough soak. Once the top few inches are moist, the water will be absorbed more easily.
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 assures evenly moisturized soil, which is a must for many plants. Healthy root development. Not that top watering doesn't promote healthy roots, but bottom watering promotes even spread and growth towards the base of the pot, which is what's most natural to plants.
“Bottom-watering” is when you put your parched plant in a bucket of water and let it soak up what it needs through the drainage hole. (It's very fun. “Like a magic trick,” said Adams.) This keeps the top of your soil dry and therefore gnat-egg-proof.
Letting a plant sit in water can cause it to rot. One of the reasons we recommend that you keep your plant in its nursery pot (the brown or black pot it arrives in) is that nursery pots have holes in the bottom, for drainage. The best way to water your plants is in the sink.
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.
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.
In general, houseplants' potting soil should be kept moist, but not wet. They normally need watering once or twice a week in the spring and summer, but less in the autumn and winter.
– Most houseplants prefer warm or tepid water over cold water, which can shock your plant. Warm water absorbs into soil best. – Some houseplants are sensitive to tap water. Let water sit overnight for chlorine to dissipate before using.
As the weather heats up and plants reach full size, you may need to water containers (and especially hanging baskets) twice a day.