Updated: Feb 7
The most common causes of excess soil moisture in potted plants are a lack of sufficient sunlight, watering too frequently and poor soil quality. If a plant’s soil stays consistently wet and is not given a chance to significantly dry out, rot can quickly spread throughout the plant’s roots and up into the stems and leaves.
Common symptoms of over watering are yellow leaves, leaf loss, water lesions on the leaves, rotten stems and discoloration of new growth, algae or mushrooms growing in the soil and stunted growth. These symptoms do not always mean your plant is dying from root rot, but are signs that your plant is not happy with the amount of moisture it is receiving .
All plants require sunlight so they can photosynthesize and produce chlorophyll. Some plants may seem to be growing fine in areas of the home where they are receiving little to no sunlight, but they will quickly begin deteriorating over time as the plant loses chlorophyll. Chlorophyll is what gives plants their green color and energy to grow healthily. If a plant is not receiving enough sunlight the paler in color it will become until it turns yellow as it loses its energy to be able to produce more chlorophyll.
A lack of sufficient sunlight can also cause your plant to grow much more slowly and the slower a plant grows the less soil moisture the roots absorb. Most plants should be placed close to windows where they receive bright, indirect light most of the day.
The further you place a plant from a window the less chlorophyll it is able to create through photosynthesis.
Some plants are advertised as low light or shade loving, but this does not mean a dark spot in your home. Even plants that prefer low light conditions still require at least bright light most of the day. Even a couple of hours of direct morning sunlight through a window will be okay for shade loving plants.
Plants can be set back a couple of feet from south or west facing windows if these windows are receiving intense afternoon sunlight, especially in the summer months. Signs of sun stress are sun burns on the top of the leaves or dry leaf edges. Plants placed below windows that aren’t getting much sunlight can be elevated onto plant stands or furniture or hung from the ceiling.
Only water your plants when the soil begins to significantly dry out. This is much easier to determine with smaller pots by sticking your finger into the first few inches of the soil to test how moist it is. Moisture meter probes can be useful for larger pots where the soil moisture at the bottom of the pot can be a mystery. Most probes go down 12” or more so you can avoid having to dig deep down into the soil. It is important to note that these meters are not always accurate and can steer you wrong if solely relied upon. If your pot is elevated you can test the soil moisture through the drainage hole. If the soil feels very wet, prolong your next watering until it dries some from a wet to a moist level. The goal is to learn how much moisture your plant is absorbing over time so you don’t have to constantly be digging around in the soil. Most plant’s soil will dry out in one to two weeks, depending on the pot size.
Water deeply until the water is running out of the drainage hole in the bottom of the pot. This will ensure all roots are receiving moisture and will reduce the frequency of how often you need to water.
Some plant stores will tell you how often to water, but this can be deceiving because watering time frames can fluctuate depending on your home’s lighting, temperature and humidity levels. It is best to learn how quickly the soil is drying out after bringing your new plant home through sight and touch.
Using the correct type of potting soil is extremely important to ensure it is not holding onto excess moisture. Potting soils for indoor plants should have a coarse composition to provide air pockets for the roots to breathe. Dense soils are designed to retain moisture and are not ideal for most home environments. Dense, moisture retaining soils become more compact over time and can cause the roots to suffocate from a lack of oxygen. Many times plants from big box stores are grown in these dense soils. This soil is great for hot, sunny environments such as greenhouses, but is not suitable for the home environment. Ferns are one of the few types of plants that prefer a dense soil as they need consistently damp soil to keep their leaves from drying out.
Choose a potting soil with added materials such as wood bark, pumice or coco coir for your tropicals and succulents.
Many small plant shops have special blends for different types of plants, but here are some recommended soils that can be found online:
FoxFarm Happy Frog - All purpose potting soil with mycorrhizae for strong root development
Tanks Green Stuff ‘De la Tanks’ - Coarse mix of compost, wood chips and pumice that creates breathing room for the roots.
Bonsai Jack Succulent and Cactus - Very coarse, gritty mixture for plant parents that tend to over water their succulents.
Harris Succulent & Cactus - Coarse blend containing compost, pumice, perlite, peat moss, bone meal and limestone
You can also make your own soil following these recommended recipes:
2 parts compost
1 part pumice or perlite
1 part wood bark or coco coir
1 part compost
1 part pumice
1 part sand
Decorative mulches such as moss or rocks are beneficial if your soil is drying out very quickly, but they can also cause your soil to hold onto moisture for long periods of time. If you notice that your soil is still very damp after a couple of weeks, remove the mulch and massage the first few inches of soil to create air pockets.
Ensure your plant’s pot has sufficient drainage. Your pots should either have a drainage hole or a pot with drainage placed inside of another pot without drainage. Very large, decorative pots without drainage can have a layer of rocks placed at the bottom with the plant potted into a separate pot with drainage placed on top of the rocks to prevent excess moisture building up at the bottom.
Choosing a pot made of a porous material such as clay or ceramic opposed to plastic will allow excess moisture to be absorbed into the pot. These types of pots are great for larger pots that can hold onto a lot of moisture at the base.
Root and Soil treatments
The best way to determine if your plant’s roots are rotting is to unpot the plant and examine its root health. Any roots that are black or mushy should be cut off completely using clean pruners to prevent the rot from spreading to healthy roots.
If you suspect or have determined that your plant has root rot, there are soil amendments that can be applied to heal your plant’s roots and encourage new root growth. These amendments contain beneficial bacteria and fungi that act as natural fungicides for bacterial and fungal diseases.
Contains a beneficial bacteria called Bacillus amyloliquefaciens which kills a variety of bacterial and fungal diseases.
Directions for use: Apply as a soil drench by mixing 1 tablespoon per gallon of water and thoroughly drench the entirety of the soil.
Contains mycorrhizae, rhizobacteria and beneficial fungi to enhance root growth and prevent bacterial and fungal diseases.
Directions for use: Soil drench: Mix one teaspoon per gallon of water and thoroughly drench the entirety of the soil. Dry application: Apply 1 tsp - 1 tbsp directly to the roots and then repot into fresh soil.
Directions for use: Apply as a soil drench by mixing 1 tsp per 8 oz of water and thoroughly drench the entirety of the soil. Direct root application: Mix 1 tsp per 8 oz of water into a spray bottle and drench the roots before re-potting.
If you need assistance in determining how to choose the right lighting, soil or watering schedule for your plant or if you suspect your plant may be suffering from root rot, we will be happy to assist you in a virtual telehealth appointment with one of our Plant Specialists. Please click on one of the options below to book an appointment.