When watering a cactus, it is advisable to do so from the bottom rather than the top. Cacti are desert plants that are designed to get their moisture more from the soil below and not so much from above, and that means they are not used to getting their foliage wet. In fact, wetting the leaves of a cactus can encourage fungal growth which could lead to stem rot.
Bottom watering is a better method because it helps the cactus to develop stronger roots by encouraging them to grow and spread in the direction of the moisture. Overhead watering only really gets the top layers of the potting mix wet and does not always reach all of the roots.
In this article, we will discuss the proper way to water a cactus, so keep reading to learn more.
Do you water your cactus from the top or bottom?
Experts recommend that you water your cactus from the bottom, because top watering does not always properly saturate the soil and therefore may not reach all of the roots. If you pour water from the top, the water may trickle through the soil and convince you that the soil is properly wet, even if only the top layers of soil are getting any water. You might have been unknowingly underwatering your plant for weeks or months!
Cacti need their potting mix to be completely soaked every time you water them so that all the roots can absorb sufficient water.
Watering from the bottom ensures that even the roots nearest the bottom of the pot get their fair share of water and, because all of the soil is well-soaked, you will not have to water the plant as often.
If you want to save time and water, you can place multiple plants to soak in the sink at the same time.
How do I water my cactus from the bottom?
The first thing is to get the timing right, because knowing exactly when to water your plant will avoid any problems related to over- or underwatering. It is best to first check the moisture level of the soil by sticking your finger about two inches into the top of the soil. If the soil in the pot feels dry, you need to water the plant, but if the soil is still damp, wait one or two days before checking it again.
Fill a large bowl or your sink with water, to a level that will reach about a third of the height of the plant’s pot. If there are pebbles and drainage rocks in the bottom of the pot, the water level should be a little higher to reach the soil.
If you are using cactus or succulent soil that has lots of draining components like perlite, you will need to give the plant more time in the water because this kind of potting medium does not absorb water as fast as regular soil.
The important thing is to have enough water in the sink that the plant is not underwatered.
Slowly lower the pot into the sink or bowl. If the plant is still in a grow pot, it might be too light and the plant could tip over in the water, in which case keep an eye on it for a few minutes to make sure the pot stays upright.
Once you are sure that the pot will not tip over, leave it in the water for 10 minutes and then check on the progress. You will know the soil has been sufficiently watered when the top layer of soil has become moist.
If, after 10 minutes, the top of the soil is still quite dry, remove the pot from the water and just water the top layers of the soil manually.
After 10 minutes of soaking, drain the remaining water from the sink or bowl and leave the plant to stand so that any excess water can drain out.
The best kind of water to use for your plant is filtered or distilled water. If you can avoid it, try not to use tap water because the chlorine in tap water can build up in the soil and damage the plant’s roots in the long run.
Bottom watering is best for small- to medium-sized cacti because their size makes them easy enough to move around and place in your sink.
How often do I need to water my cactus?
Even if you know how to properly water your cactus, it will still be for naught if you do not know how often you should be watering it.
Cacti are some of the most hardy and resilient houseplants and, because they can store water in their bodies, they can go several weeks without being watered. Despite not requiring frequent watering, however, you cannot neglect them willy-nilly. Cacti are also susceptible to the effects of underwatering if you leave it too long. If you can see that the potting medium is dry to the touch and if the cactus itself looks dry with brown or crisp leaf tips, it could be severely dehydrated.
One of the factors to take into account with regard to watering frequency is whether the cactus is in a pot or growing in the ground. Also take note of the amount of light it is getting, the temperature where the plant is kept, and the humidity level.
The most important thing to remember is never to let the soil become soggy or waterlogged. because a cactus will not survive for long in such conditions. The soil in the pot needs to be porous and loose enough that it drains well and quickly.
Dense, compact soil will retain too much water and can lead to root rot, a condition caused by prolonged exposure of the plant’s roots to waterlogged soil. Cacti need their roots to be able to dry out between waterings, otherwise they cannot absorb oxygen and will drown and die. The dead roots will become susceptible to opportunistic pathogens, such as fungi and bacteria, which will cause the rot to spread even faster to the rest of the plant and may even kill it eventually.
How can I salvage an overwatered cactus?
If you think your cactus has been overwatered, you need to stop watering it immediately. Move it to a sunny spot where it can get lots of light and do not water it again until the soil in the pot has dried out completely.
If the cactus’ leaves have already turned pale yellow, and if some of them feel soft and mushy to the touch, you need to consider the possibility of root rot. To confirm this, you will have to uproot the plant. Remove it from its pot and wash off as much soil as you can from the roots. Do this gently, because the roots will be quite fragile in their current state.
After washing off the soil, inspect the roots closely for sections that have turned brown or black; these are rotten and will need to be removed. Use a sterile knife or pair of scissors to cut off the rotten roots, leaving only healthy, white roots behind. Then, lay the plant on a dry paper towel and let the roots air-dry for a few hours.
Prepare a new pot that has drainage holes at the bottom and fill it two-thirds with well-draining potting mix. Place the plant in the middle of the pot and cover the roots with more soil.
Do not water the plant yet; wait at least a week to give it time to recover from the trauma of repotting.
When watering your cactus, it is better to water the bottom than from the top.
Watering a cactus from the top will wet the foliage, which can encourage unwanted fungal and bacterial growth.
Water your plant from the bottom by placing the pot in a sink or bowl filled with water. The water will be absorbed through the drainage holes at the bottom of the pot and the soil will be moistened from the bottom up.
Water your plant only when the top two inches of soil are dry to the touch. If the top layer of soil is still damp, wait one or two days and check it again.
Image: istockphoto.com / Sundaemorning