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.
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.
Can you overwater by bottom watering? 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.
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.
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.
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.
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.
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.
High moisture levels in the soil can increase the risk of fungal, viral and bacterial infections in your plants. Overwatering might still happen in a pot with drainage holes, but the risk of over saturated soil is much lower.
“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.
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.
– 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.
How to Use Pots with No Drainage Holes. Some experts suggest using a layer of pebbles as a sort of drainage layer in those pots without drainage holes. This technique allows excess water to flow into the space with the pebbles, away from the soil and, therefore, the roots of your plant.
Gardening FAQ
The problem with your soil resisting hydration is not uncommon. It usually begins with the soil being watered incompletely and then drying more than it should. After that it can become hydrophobic and actually repel water! The ingredient in the soil that is causing that problem is peat.
If you're ready to give bottom-watering a try, it's really quite simple. Fill a bowl or saucer with room-temperature water, and mix in some fertilizer, if needed. From here, you can simply place the plant in the container and let it sit for 15 minutes or so.
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.)
Simply stick your finger in the soil and if the first inch is dry, water. If it looks dry on top but is actually wet below the surface, don't. “There are many different types of water meters out there, but nothing is better than getting to know your plant by your own touch,” Cramm says.
Just dip your index finger into the soil near the stem of your plant up to about your first knuckle. If the soil feels dry, and your finger comes out clean, then it's probably time for some water.
It depends on the size of the pot, type of pot (plastic or clay), how dry the soil is, the type of potting medium, and the density of the root ball. Larger plants might need a few hours, whereas small plants in smaller pots will take considerably less time. Some people even bottom water their plants overnight.
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.