Whether you’re growing annual flowers or vegetables in pots on your patio, or have a jungle of perennial potted plants in your living room, the quality of the soil that they’re growing in makes a huge difference in the health of your plants. One of the most common problems that may arise over time is soil compaction.
Is Compact Soil Bad for Plants?
When soil becomes compacted, it can severely impact the growth of your plants. That’s why experts recommend loosening up the soil in garden beds before planting annual flowers and vegetables, and it’s equally important for container growing.
When soil becomes too dense and packed, it’s harder for the roots to do their job of absorbing water and nutrients to nurture plant growth. As well, when the soil gets compacted, water tends to run right through instead of remaining in the soil where it’s needed.
What Causes Soil Compaction in Gardening Pots?
There are a number of ways that you can end up with soil compaction. Obviously, not using a soil mix that will maintain a loose, open structure is a common problem. And even the best soil mix will get compacted over time, so if you haven’t repotted in a year or so, problems will develop. Overwatering without letting excess water drain out is another common cause.
How Can You Tell If the Soil in Your Pots Is Compacted?
If your potted plants have yellowing leaves and seem wilted, even with regular watering and feeding, check the soil; there’s a good chance that compaction is the culprit. It will be easy to tell: feel the soil. If you can easily poke a finger into it, and it seems loose and flaky, your soil is fine.
However, if it’s hard and lumpy, and you can’t push your finger into it without meeting a lot of resistance, imagine what’s happening to the delicate roots of your potted plants.
Read our related post Accidentally Used Garden Soil in Pots? (Here’s What to Do!) here.
Can You Prevent Soil from Getting Hard in Pots?
Before things get to this stage, there are ways to keep soil from getting compacted.
Start with a good soil mix for container planting. Do not use ordinary top soil for planting in pots, as it will not have the loose, open structure that potted plants need for healthy growth. Look for potting soil mixes which contain perlite, vermiculite, or peat moss, or any combination of those soil amendments. They will keep soil from getting packed down and let the roots breathe.
If you’re replanting annuals in outdoor pots every spring, you should always start with fresh soil. In the fall, I dump the old soil into my vegetable beds before storing my deck pots away for the winter, and then start with a fresh potting mix in spring.
Make sure that the soil never dries out completely, as that can create an impervious barrier to water. It’s best to water from below, rather than on the soil surface. If possible, plunge the whole pot into a pail of tepid water and let it fully absorb the water. Then, let it drain completely before setting it back in the saucer.
A good way to maintain adequate soil moisture and prevent soil compaction is to spread a layer of mulch over the soil surface.
How to Loosen Compacted Soil in Pots?
All of your best efforts have failed, and the soil in your containers has turned into an impermeable brick? Don’t give up; there’s hope for those plants yet!
Aeration
If it’s the wrong time of year for repotting, you can still loosen things up. The easiest way is by poking a chopstick down into the soil. Don’t get too rough, as you don’t want to damage the delicate roots that are already struggling in the compacted soil. Gently wiggle your way down through the soil, and then water thoroughly. If you had trouble getting down to the bottom of the pot, repeat the process the next day after the water has started to loosen things up. This should buy you a few months until you can repot.
Adding Soil Amendments
While you’re creating holes with the chopstick, you can also add some fresh soil amendments. This is the perfect opportunity to incorporate nutrient-rich compost to feed the roots as well as improve the soil texture. Good quality compost is also teeming with microbes that will reinvigorate lifeless soil.
Replacing Soil
At some point, you will have to repot your plants with fresh potting soil, and that’s the time to learn from past mistakes and create the ideal soil mix that will stay loose and well-draining for a longer stretch. There are lots of pre-mixed potting soil mixes out there if you’re not confident of your ability to create your own, but be careful; not all mixes are high quality.
If you want to mix your own, try equal proportions of well-rotted compost, peat moss, and perlite. For plants that really appreciate a loose soil, such as orchids or philodendrons, adding chunks of bark will further open up the soil structure and let the roots breathe.
Final Thoughts
When you’ve invested time and money in potted plants, the last thing you want is for them to suffer in compacted soil. Using these tips you should be able to ensure a long and healthy life for your plants!
Janice is a retired High School teacher who is spending her leisure years keeping busy with all sorts of projects. Aside from freelance writing, she’s an enthusiastic amateur chef, home wine maker, and tends a large raised-bed vegetable garden, while at the same time running a Bed & Breakfast.