Sometimes, too much TLC showered by over-zealous growers can be the bane of their plant babies. Overwatering is a leading cause of indoor plants failing to thrive or dying prematurely. Wet indoor plant soil can cause root rot and fungal disease.
You must first identify what’s causing indoor plant soil to stay wet. Depending on the cause, you may have to improve the drainage of the potting soil, adjust the indoor temperature and humidity levels, or move the plants to a brighter and more airy site. Using a porous pot can keep the soil dry.
To fix what’s keeping plant soil damp, you must know why it stays wet. In this article, I will describe what causes indoor plant soil to remain soggy after watering and explain how you fix each issue.
Why Does My Plant Soil Stay Moist?
Your indoor plant soil may stay moist if the room temperature is low, the ambient light is insufficient, or there is inadequate ventilation. The soil can stay wet if the planter has too few drainage holes or they are blocked. A poorly-draining potting mix can also keep the soil moist.
Fortunately, these conditions can be rectified quickly. Your waterlogged plant can be saved and revived if you detect the cause early and take remedial measures promptly.
Read on to know more about the reasons that keep indoor plant soil moist and how you can fix the issues.
The Soil Does Not Drain Well
Poorly-draining soil is a common cause of waterlogged conditions in indoor planters and root rot and fungal diseases in plants.
Most store-bought potting mixes for indoor plants are formulated to retain water, but they tend to have poor drainage. This results in the soil staying wet for a long time.
Sometimes, plant growers add soil from their yards to their homemade potting mixes. Garden soil is usually heavy and dense and tends to hold on to water. This is especially true if the native soil in your area is clayey.
Watch out for the following signs of indoor plant soil not draining properly:
- Water collects on the surface of the soil after watering.
- Water takes a long time to drain out of the holes at the bottom of the container, even after you have thoroughly soaked the soil.
- The soil is dry just beneath the surface. Insert your finger a few inches into the soil. If it feels dry to the touch and the surface is wet, water is not permeating the soil.
How To Fix Poorly-Draining Soil
The best way to fix poorly-draining soil is to add perlite or pumice to a store-bought potting mix. You can also add coarse sand to improve drainage.
DO NOT use garden soil in your homemade potting mix.
Also, avoid adding too many water-retaining ingredients into the potting mix. For instance, perlite, sphagnum peat moss, and coco coir hold on to water. Do not use these three ingredients together in the potting mix.
If the soil in an existing container does not drain properly, you must remove the plant and repot it using a fresh potting mix.
Check how well the potting mix drains before planting. This ensures you don’t have to pull out the plant afterward and risk damaging its roots. Here’s how to check for drainage before transplanting:
- Fill about half the pot with the potting mix.
- Soak the soil thoroughly.
- Wait for the soil to absorb the water.
- Ensure the water flows out of the bottom of the pot after some time.
- Insert your finger a few inches into the soil to check if water has saturated the potting mix.
- Repot your plant after ensuring the soil is draining properly.
Before transplanting a waterlogged plant, check for root rot and fungal growth. Prune mushy and rotted roots and snip away yellowed leaves. Gently remove as much wet soil as you can without disturbing the roots.
You can use a hairdryer on the cool setting near the soil in the root zone to dry the plant. Or, you can wrap the plant’s root zone in a newspaper and gently press to let the paper absorb the excess moisture.
The Pot Has Insufficient Drainage Holes
Excess water cannot drain out of the planter if there are insufficient holes at the bottom. Always check for drainage holes before buying a planter or planting.
Many DIY enthusiasts prefer making planters home using ingredients like Portland cement. These pots are called hypertufa pots.
Ensure that you make drainage holes in these pots. I advise that you make at least two holes if the pot is large.
Here’s a video on YouTube uploaded by Kim’s Garden that shows how to make drainage holes in hypertufa planters:
The Drainage Holes Are Blocked
The drainage holes at the bottom of a planter tend to get clogged with damp soil over time. This prevents excess water from draining out of the container and creates waterlogging conditions.
Here are some tips on how to prevent the drain holes at the bottom of a planter from getting choked:
- DO NOT line the bottom of the planter with terra cotta shards, rocks, pebbles, or gravel.
- Use coco coir discs, fine plastic mesh, landscape cloth, or woven weed barrier to line the bottom of the pot.
- Use only a chunk of terra cotta or a piece of rock to cover a drainage hole.
The Room Temperature is Too Low
Most indoor plants thrive within a temperature range of 65°F and 75°F (18.3-23.9°C) during the day and 55°F and 65°F (12.8-18.3°C) at night.
The ideal temperature for a specific indoor plant depends on factors like the species of the plant, season, time of the day, and indoor humidity levels. However, most houseplants fail to thrive, and some even die when the temperature falls below 50°F (10°C).
Very low temperatures can cause indoor plant soil to remain wet. Here’s why:
- Low temperatures decrease the evaporation of water from the soil.
- Low temperatures decrease the rate of transpiration from the leaves of the plant, so plants use less water.
- Plants grow slowly in cold weather, so they take up less water from the soil.
- Cold temperatures can damage a plant and send it into shock so that its growth slows, and it cannot take up water from the soil.
Cold temperatures and wet soil can be lethal for plants. The damp soil attracts fungus and mold and damages the plant. Follow these tips to prevent cold temperatures from keeping indoor plant soil wet:
- Use a thermometer to monitor temperatures. Some digital thermometers record maximum and minimum temperatures along with the real-time temperature. These values help you gauge if there are wide fluctuations in temperature throughout the day.
- Place the plants away from cold drafts. Remove the plants near a leaky window or door through which cold drafts can enter the house. Also, do not keep the plants in corridors that tend to be cold and drafty.
- Keep your plants far away from cooling appliances. Cold drafts from the vents of cooling appliances can cause drastic temperature swings.
- Crank up the room heater. Consider setting the room heater to a higher temperature after accounting for the comfort levels of the inhabitants.
- Move the planters to a sunnier or warmer site. Move the planters near a south- or west-facing window or porch where the sun will warm the soil and keep it dry. Do not keep the plants in rooms that tend to be naturally cool due to their position, such as a north-facing room or one shaded by a large tree or a tall building.
- Do not overwater. Wait for the top few inches of the soil to dry out before watering, especially in fall and winter when it is cold and most indoor plants enter a period of dormancy.
The Ambient Humidity Level Is High
When the indoor humidity levels are high, and the air is saturated with moisture, evaporation of water from the soil and transpiration from the leaves reduce. So, the soil remains wet.
High humidity also attracts fungus, mold, and pest attacks that sicken the plant and stunt its growth. As a result, the plant cannot use the water in the soil.
Here’s how you can bring down the humidity level around your indoor plants:
- Tweak the controls of the humidifier.
- Move plants farther apart. Closely spaced plants create a humid microclimate.
- Trim the leaves on the lower branches. This will expose the soil to the air and help it dry quickly.
- Do not let water stagnate in the drainage saucer. Stagnant water keeps the soil near the plant’s root zone always wet. Water stagnating in the drainage saucer can also cause root rot and fungal diseases in plants.
- Mist moisture-loving plants. Some people fill a tray of pebbles with water and place it underneath moisture-loving plants. This strategy might increase humidity levels excessively and should be avoided. Consider misting the leaves of the plants instead.
However, most indoor plants originating in the world’s tropical regions thrive in warm, moist air.
Also, excessively dry indoor air can make a living space uncomfortable and trigger breathing problems in vulnerable people.
So, you must strike a balance between keeping the air humid enough for your plants and healthy for the people using the space while ensuring the soil does not remain wet.
The Ambient Light Is Low
Most indoor plants thrive in brightly-lit spaces. Low-light conditions stunt their growth.
A plant that isn’t growing well doesn’t use up resources. It has much less use for water because it is not thriving. So, the soil remains wet long after watering.
It is not difficult to fix the issue of low-light conditions keeping plant soil wet.
Move the plants to a brighter location. You can keep the planters near a window or a porch that receives ample sunlight.
Grow lights provide light and warmth to indoor plants. These lights speed up plant growth, and the heat they produce keeps the soil dry. Here are some tips on how to effectively use grow lights for indoor plants:
- Research the ideal lighting conditions for your plants. Long-day plants need more daylight hours than short-day plants. It is a waste to keep the lights on when your plants don’t need them. Also, short-day plants need a period of darkness to flower.
- Switch off the lights to allow a period of respiration. You cannot leave the lights on continuously even if the soil remains damp. A plant needs a period of respiration, ideally at least six hours per day, to process the nutrients it takes up during the day and produces food.
- Hang the grow lights at an appropriate height. LED grow lights generate more heat than illumination. You should hang these lights at a proper height, so the plants are not burned. On the other hand, you must hang the less-powerful T5 fluorescent lights low to ensure plants don’t get leggy trying to stretch toward the light.
Do not use powerful lights just because you want to keep the indoor plant soil dry. That’s because more light does not always equal higher yield or vigorous plants. You have to consider the lighting needs of your plants to ensure the lights support their growth instead of stunting them.
I have described how to use artificial grow lights for indoor plants in my article here: How Many Lumens Does It Take to Grow Herbs Indoors
There Is Poor Ventilation in The Room
Poor ventilation in the room slows down the rate of evaporation of water from the soil and transpiration from the leaves. This keeps the soil moist.
Inadequate ventilation can also attract fungus and other pests that can damage the plant. A sick plant does not have the energy to grow, so it does not use the water it is being fed. As a result, the soil remains wet.
Here’s how you can improve ventilation in a room:
- Switch on the fan.
- Open a few windows during the day.
- Increase the distance between planters to let air flow through and around the plants.
- Thin the plant canopy to improve air circulation through the leaves.
Besides preventing indoor plant soil from drying out, a poorly ventilated room is also unhealthy for people inhabiting the space.
You Have Mulched Too Thickly
Mulching is an excellent horticultural practice. Besides preventing the growth of weeds, mulching preserves moisture in the soil.
However, thickly mulching indoor soil can sometimes keep the soil wet. If you think that the soil in your indoor planters is not drying out quickly, try removing the layer of mulch from the top. This will expose the soil to the air and allow it to dry.
The Pot Is Too Large
Plants must be repotted and moved to a larger pot when they outgrow their present containers. So, many growers tend to use large pots for their plants to save on the time and effort of repotting.
However, large pots hold more soil. More soil retains more water and takes longer to dry out after watering. So, your plant sits in a pool of water unless it is big enough to use up the water or is of a particularly water-thirsty variety.
Use a pot that is appropriately sized for your plant. Give your plant space to grow, but do not use a container that is larger than what your plant needs.
The Pot Is Non-Porous
Planters made of non-porous materials like plastic and metal retain more water than terra cotta pots. Although plastic pots are light and can be moved around easily, keeping the soil dry in these pots can be challenging.
If you use planters made of a non-porous material, water judiciously. Else, move your plants to terra cotta pots.
Can You Dry Out Wet Soil?
You have dried and repotted your waterlogged plant, but now you have a lump of wet, soggy soil in your hands. What should you do with it?
If the waterlogged plant you salvaged was not afflicted with a fungal disease or did not have root rot, you can reuse the soil it was planted in. You have to dry it before reusing it.
You can dry out wet soil by removing it from the pot, spreading it out, and drying it with a hair dryer or exposing it to the sun or wind for a few days. You can mix dry soil or hydrated lime with damp soil to dry it. Overwatered soil can take 1-3 days to dry out, depending on how you dry it.
Using a hairdryer can heat up the soil excessively if you aren’t careful. This will kill the beneficial microorganisms residing in the soil. When using a hairdryer, quickly move over a section of the soil so that the heat doesn’t scorch it.
Hydrated lime or slaked lime increases the soil pH. Keep this in mind when reusing this soil for other plants.
You have to use more than one ploy to fix the issue of wet indoor plant soil. For instance, using a terra cotta pot will not prevent waterlogged soil if there are no drainage holes in the container. Or, poorly-draining soil will become waterlogged even if you keep indoor temperature and humidity to optimum levels.