The roots of the plant take up water but they also need air to breathe. Over-watering, in simple terms, drowns your plant. Soil that is constantly wet won't have enough air pockets and the roots can't breathe. Roots that can't breathe are stressed roots.
The good news is that most plants will bounce back between 7-14 days if they're given proper care (which includes rehydration). If this isn't possible because major damage was done or little healthy root system exists then expect about 2 weeks until improvement can be seen.
Repot your plant in new soil
Sometimes letting the soil dry out takes too long and your plant is showing serious overwatering symptoms. If you let the soil dry out, it could take days and your plant might not be able to survive days in the soil. In this case, you can repot your plant in dry soil.
To dry out soil quickly, you can apply hydrated lime to the soil, add compost and then turn the soil thoroughly to aerate it.
It may take an hour or more to thoroughly re-wet the soil. Be careful not to leave pots soaking in standing water continuously. Check them after an hour or two and remove them when they are hydrated.
Using a hairdryer directly on the soil is an easy way of removing that excess moisture easily. However, there are some things to take into consideration when doing so. When directed at the soil the dryer will only remove the moisture from the surface having the rest of the soil wet.
Signs of root rot are slow growth, mushy stems, and wilting, yellow, distorted leaves (especially when the plant has been well watered, as wilting leaves can also be a sign of a dry plant).
If a plant is overwatered, it will likely develop yellow or brown limp, droopy leaves as opposed to dry, crispy leaves (which are a sign of too little water). Wilting leaves combined with wet soil usually mean that root rot has set in and the roots can no longer absorb water.
You can either go for the bath method and bottom water, or thoroughly top water. I prefer to give plants a bath (bottom water) as step one, a day or two before I repot, then I like to thoroughly top water drench after repotting, as top watering also helps flush out excess dirt and silt from the new substrate.
Yellow Leaves + Fading to Green + or Bright Yellow =
These symptoms together mean that your plant is overwatered. Usually lower leaves drop first, although the whole plant may be affected. The solution = repot (to remove soaked soil) and water less, or let soil dry out and water less.
Look out for signs of overwatering – including a limp plant, yellowing leaves, or dropping leaves. If you see these signs, test the soil with your fingers. It should be pretty obvious if it's soggy! Stop watering and let the soil dry out.
In the most extreme cases, when conditions are ideal for the fungus to spread quickly, plants can die within 10 days. If these symptoms occur in a plant, loosen the soil around the base of the plant with a hand trowel or shovel and remove the plant from the soil.
However, Epsom salt can still help a tomato plant where the soil is too alkaline or one that has been overwatered. In this way, it helps boost absorption as well as improving photosynthesis in the existing foliage.
The main ways to make soil dry faster are to increase light, heat, and ventilation for your plant, ensure the soil and pot are draining well, and choose an appropriately sized pot for your plant. Consider moving to a pot made of a porous material such as terracotta, and make sure to drain the pot well after watering.
A yellow leaf has lost its chlorophyll (pigment) and it can't turn green again even after you correct the problem. Don't worry, if the plant regains its health, it's possible that new leaves will fill in during the next growing season. Growing plants is always a matter of patience.
One of the quickest, first signs of overwatering your plants is to observe occurs at the tip of the leaf. If the tip of the leaf is turning brown this is a sign of overwatering. Too little water will result in your plant's leaves feeling dry and crispy to the touch while too much water results in soft and limp leaves.
If overwatering is the issue, the roots will look dark and feel mushy to the touch. The plant's soil may also give off a sour, funky smell, due to water-loving bacteria forming around those roots.
The primary symptom of excess moisture is wilting or yellowing of lower and inner leaves. If excess water continues, plants may show other drought symptoms, such as scorch, leaf drop, and/ or plant death. Plants should be watered when needed.
Hydrogen peroxide can help to control fungal growth and fungal infection, such as root rot, by preventing the growth of fungi. It can also help kill fungus and bacteria on plant roots.
Q. How often should plants be watered? Water once or twice per week, using enough water to moisten the soil to a depth of about 6 inches each time.
Make sure the plant is well watered 2-4 days in advance. You don't want to repot when it's sopping wet but being too dry will cause stress. Take the plant out of the pot. If the rootball is a bit tight, gently massage the roots to loosen them up.