Instead of pouring water from above, many people like to water their houseplants, including orchids, from the bottom.
Is it also better for watering your indoor succulents?
Bottom watering is not only an alternative to watering from above. Bottom watering is actually necessary to keep succulents hydrated and alive especially when the soil gets too compacted and water-repellant from frequent drying, when they get pot-bound, and when they are vulnerable to rotting.
In this article, we will explain what makes succulent growing so unique for this watering technique to be necessary.
1. What is “bottom-watering”?
Bottom-watering is an automatic watering technique by placing a tray of water under the pot of a plant. Water gets wicked or drawn upwards by capillary action when the soil which touches the water tray is dry.
Depending on the needs of the plant, it can be sitting on a tray with only 1-2 inches deep of water, or it can be submerged, or soaked, in a deep container or an outer cache pot of water.
2. When is bottom-watering necessary for succulents?
Bottom watering is often considered an alternative to watering from above. Indeed, watering from the bottom has the advantage of preventing water and soil from splashing as you pour water from above.
But there are three situations when watering from the bottom is not only preferable but necessary to keep your succulent alive.
Depending on the severity of the situation, in some cases giving your succulent a shallow tray of water on the bottom will suffice while in other cases you will need to submerge, or soak the pot deeply in water.
2.1 When soil is compact and hydrophobic
You should water your plants from the bottom when the soil is compact.
This often happens a couple of months after potting up a succulent: the soil starts to shrink, becomes compacted and pulls away from the pot, leaving a gap on the sides of the pot.
If you pour water into a pot with compact soil, water does not penetrate into the core and near the roots. Rather, it runs off on the sides of the pot and drains out on the bottom.
This is a dangerous situation because you may think that you have watered your plant, but in fact, your plant cannot absorb the water and will become dehydrated.
Potting soil often becomes water-repellant, or hydrophobic, because it has been dried for a while. The presence of peat makes it worse because it absorbs much water when moist but repels water when it is dry.
Another cause for soils to become hydrophobic is a build-up of organic matter where soil particles are coated with wax-like organic acids produced from the decomposition of organic matter due to fungal and micro-bacterial activities.
The problem of compacted soil is common in substrates that are high in organic matter (e.g. peat, compost) and succulent pots that are often left dried out between watering.
2.2 When succulent is pot-bound
Succulents get pot-bound easily when the pot is too small especially for succulent arrangements.
Another situation when they get easily pot-bound is when they become too big as they grow in size, mature and reproduce new pups that fill the pot.
In particular, succulents with broad and thick leaves often cover the pot, leaving little space for watering from above.
Here are examples of some common broad-leaf succulents which often fill or cover the top of the pot:
- Flat-topped Aeonium (Aeonium tabuliforme)
- String of Pearls (Senecio rowleyanus)
- Agave colorata
- Agave victoriae-reginae
- Agave bracteosa
- Haworthia emelyae
- Haworthia retusa
- Haworthia truncata
This also happens especially when you have not repotted your plant for a long time, like with root-bound orchids.
Succulents that are pot-bound result in little space for soil and thus a lower capacity to hold water. Thus, having direct access to water via bottom-watering would be more beneficial.
2.3 When succulent is susceptible to rotting
Some succulents are more vulnerable to rotting, especially during winter. For them, watering above will increase the chance of getting sick as it is easy to splash water and soil up to the leaves.
2.4 When you do not have time to water
Watering from the bottom or a reservoir is a self-watering system that is most suitable for those who are away or do not have time to water their plants as water is drawn up to the soil automatically when it is dry.
3. How to water succulents from the bottom?
To water succulents from the bottom, fill a large deep tray without holes with 2 inches of water and place all your succulents in the same tray for up to 30 minutes maximum.
Remove the tray when the soil feels moist when you touch the soil surface. You will then know that water has been wicked up to the top.
Alternatively, you can place the plant in an individual tray or a Tupperware.
For succulents with compact soil, you will need to submerge the whole pot in water. Initially, you will need to hold the pot down to prevent it from floating and you will see air bubbles forming because of the air in the soil. When bubbling stops, which can be a few minutes after, you can remove the pot from the bucket of water.
For succulents planted in the ground or in pots that are too heavy to lift, you can trickle water slowly from above. This requires patience as it can take a long time to water them.
Here is a durable plastic tray without holes that is perfect for watering several pots from the bottom.
4. How often should indoor succulents be bottom-watered?
The leaves of your succulents are the best indicator of when to water.
You should water only when the soil is completely dry or when shows signs of dehydration, such as leaves shriveling, leaf dropping, soil becoming compacted.
Depending on your environment, the rule of thumb is generally to water once a week or once every two weeks.
After all, the thicker the leaves and stems which are areas of water storage, the more drought-resistant your succulent is and the less frequently it needs to be watered.
5. Can succulents be overwatered by bottom watering?
Watering your succulents from the bottom is less likely to be overwatered, compared to watering from above.
But, leaving your plants on the tray of water for too long and too frequently will likely lead to overwatering.
6. Will bottom-watering cause root rot?
Root rot or mushy roots is one of the symptoms of overwatering. Other symptoms include yellow leaves, rotting and disease.
If this happens to your plant, you can cut the infected roots using clean, sterilized cutters. But this will only work if the affected area is small.
Another method is to use fungicide like Physan 20.
Here is a short video to help you understand how and when to bottom-water your succulents to avoid root rot from occurring in your plants.
Bottom-watering is a better technique for watering succulents when the soil is compacted, when your plant is pot-bound, and when the plant is more susceptible to root rot.
This can be done by soaking them in a deep tray of water for not more than 30 minutes until they are moist to top on the top of the soil.
Olorunfemi, I.E., Ogunrinde, T.A. & Fasinmirin, J.T. (2014). Soil Hydrophobicity: An Overview. Journal of Scientific Research and Reports. 3(8). pp 1003-1037.
University of Maryland. (2021, July 22). Watering Indoor Plants.