By Deb Pavlosky
Have you ever looked at a container planting and wondered what the heck happened to all the soil that was in that pot? Well, though you may think differently right now, soil doesn’t disintegrate in the Texas heat. And there’s no magic, naughty garden gnomes or desperate neighbors involved in disappearing soil either.
Soil is not just dirt. Soil, at least good planting soil, has lots of organic matter with nutrients that your plants need to uptake in order to survive and thrive. As plants use up the available nutrients, the soil shrinks and the soil level lowers in the pot as this happens. This doesn’t happen overnight, but the longer you have a container planting, the more you will notice this problem. Because nutrients are getting used up, container plants need to be fertilized on a regular basis. If your plants are healthy, you can let trimmed or fallen parts of plants sit in the pot to decompose, returning some of the used nutrients to the soil as they do. Don’t do this if your plants are fighting any pathogens or pests, but do fertilize with a good organic fertilizer to support your struggling plants.
Another factor to consider is simply compaction of the soil over time. Soil will naturally collapse on itself and will compact under the influence of water as well. It’s always a good idea to fill a pot a little fuller when planting a new container. The soil level should not be above the original soil level of the plants, but closer to the top of the new container than you think. Just make sure that you don’t lose soil out of the top of the pot as you water.
One other thing to consider is that sometimes you can lose soil out of the bottom of a pot. I used to “poo poo” this thought. I had never seen soil come out of the bottom of any pot that I had ever planted – until this year, that is. I have a very wide pot that has a large drainage hole in the bottom. I thought twice about putting something to prevent soil from falling out, but decided not to and was fairly certain that was the right decision since I didn’t lose any soil when planting. Well, just a few weeks after planting, soil started falling out of the drainage hole. Bummer. Because now I know I will need to replant this pot sooner rather than later. You can easily prevent this from happening by placing a piece of screen over the drainage hole inside the pot before you add soil for planting. I highly recommend doing this, especially if the drainage hole in your pot is large compared to other pots.
So, there you go. Soil does not have legs and the dogs probably aren’t eating it (though some find Microlife tasty). Shrinking soil is a clue that your plants are using up all the good stuff and it’s also a reminder to repot your plants into new containers too. Take the cue and have some fun with your container plantings.