Have you ever gone to water your containers only to have the water run right out the bottom, leaving dry soil behind. That happens when we let the soil get too dry between waterings and it can be an annoying and messy problem to fix.
Why it pulls away
Most potting soils have a lot of peat in them. Although peat is considered moisture retentive, it takes awhile for dry peat to start soaking it in. If you’ve ever tried wetting a bag of peat, you know what I mean. Once it’s wet, it’s fine, but if you let it dry out again, you have to repeat the soaking process.
This can be a problem, when the potting soil is in a container. As the soil dries out, it shrinks and pulls away from the sides of the container. Now when you try to water it, the water just flows down the empty sides and out the bottom of the pot.
How to Get the Soil Wet Again
You can slowly keep adding water to the center of the root ball and wait for it to expand or you can take the whole container and plunk it into a larger container filled with water. Do this slowly, so the root ball does not float right out of the container. If necessary, weight it down with a rock or brick.
If your container is too large or heavy to do this, you can also put a shallow tray under it and keep adding water until it has all been absorbed and the soil has expanded. This will take a while longer. How long depends on the size of your container. Or try Alan’s suggestion below and tilt the container enough to temporarily plug the holes with corks. Just remember to unplug them, when the soil is saturated.
Watering Rules of Thumb
Know What Your Plant Likes – Plants are very diverse in their need for water. Some need constant moisture, some need a good soaking and some time to dry out and others only need occasional watering. Read up on what your plant prefers so that you don’t have to wait until it wilts, to know it’s time to water.
Test the Soil – Rather than a rule of thumb, use your index finger to test the soil. Poke it down about an inch or so (the 2nd knuckle) below the soil surface. If it’s dry down there, it’s time to water.
Water in the Morning – Plant roots absorb better during the cooler times of day. Watering in the evening can leave your plants damp and susceptible to fungal problems, so watering in the morning is the ideal time. Of course, if it’s an extremely hot day, you may need to water more than once. Containers will also need more water as their roots fill out the pot.
Let it Drain out the Bottom – To ensure all the roots get watered and to prevent the soil from pulling away again, make sure you soak the entire root ball. The best way to do this is to water until it starts to leak out the bottom of the container. (Your container does have drainage holes, right?) Along with giving the roots a good drink, allowing the water to leech through also drains away any built up soluble salts, from fertilizer or the water itself. Salts can injure roots and leaves.
I am the first person to admit that watering plants is a tedious garden chore, but we can’t count on rain. Hopefully we can water often enough to not have to deal with shrinking root balls again.