Tip. Even if the plants are suitable for bottom watering, they should be top watered once every four to six months, because soluble salts from the fertilizer build up in the potting medium. Top watering until water runs out of the bottom through the drainage holes is the only way to flush out those salts.
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.
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.
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.
Wetting leaves.
Plants get their moisture through their roots, not their leaves. Direct watering to the soil surface and avoid wetting leaves because water helps spread some plant diseases. Use a watering wand to reach ground level or a soaker hose or trickle irrigation system to wet the soil rather than the leaves.
Warm water absorbs into soil best. – Some houseplants are sensitive to tap water. Let water sit overnight for chlorine to dissipate before using. – Plants in large planters dry out more slowly than plants in small planters because of the volume of potting soil.
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.
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.
Avoid showering plants that don't like to get their leaves wet (such as African violets, Cyclamen, and Begonias). Did you fill your plant container with anything besides potting mix or potting soil?
If you don't have a drainage hole in your pot, you probably shouldn't use it for an outdoor plant, unless the plant will be sheltered from rain. You need to micromanage the amount of water going into your pot; if it get's drenched in a downpour, all could be lost. More soil means more moisture for longer.
Stop Watering the Plant
But stopping your watering is always the first step. If you're overwatering, you'll likely notice that the soil is wet, so you want to make sure that soil is bone dry before you're ready to break out the watering can again.
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.
DON'T water too frequently—or not frequently enough.
Instead, opt for a less frequent watering routine that thoroughly saturates the soil. This method encourages the plants' roots to reach deeply for residual water, even when the surface of the soil appears dry.
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 a general rule of thumb, most of our customers who are utilizing the most common types of spray heads can comfortably water their lawn for 10 minutes at a time. If you're running rotor heads, you can bump that time up to 20 minutes.
Water Only When Needed
Too much water can be just as damaging to plants as too little water. Before watering, check your garden's soil moisture with your finger. Push it into the ground around your plants. You want the top 2 or 3 inches of the soil to be dry, and the soil below that to be moist.
When bottom watering potted plants, the key is in the timing. Push your finger into the soil between the wall of the container and the stem of the plant. If you push down to the second knuckle and still don't feel moist soil, it's time to water the plant.
Never be tempted to over-water. Over-watering is equally as harmful as under-watering. 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.
“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.
Pro: Bottled water can be a great alternative to tap water, if the local water is not safe for plants. If bottled water is the easiest option for you, try to use bottled spring water as it contains natural minerals that help plants grow.
The key is to be patient. Keep tending to your plant for a few weeks and then reevaluate. “Once you've taken steps to revive a dying plant, it can take up to a month before you start to see an improvement or new growth, so don't give up on it too soon,” says Valentino.
“If soil is left too wet for too long, it can cause root rot,” Marino says. “That's what we call over watering. On the other hand, if your plant's soil is consistently too dry you're likely under watering. Letting your soil dry out before watering is key for plants to receive the perfect balance of water and oxygen.”