Why Does My Potting Soil Get Hard? (And How To Fix It)

You are using the right potting soil to grow your container plant but after some time the soil has turned hard. And now your plant is not getting the required moisture as the soil is not absorbing the water.

Your potting soil gets hard because of underwatering. You have not provided frequent watering to the soil causing it to become hydrophobic. You can recover the potting soil by soaking the pot in water for an hour so it starts absorbing water again.

I’ve written all the details below that will help you understand why your potting soil gets hard and what you can do to fix the problem.

If you don’t remember to water the potting soil often, it may be a good choice to use a self-watering container and avoid the problem. Check out the best self-watering containers on Amazon.com.

Underwatering

The most common reason your potting soil will get hard is if you are not providing the plants with consistent watering.

Many potting soil varieties contain peat moss that is supposed to be hydrophilic. This means it will absorb the moisture when you water it and release it slowly for the plant.

But if you keep peat moss for a long time without adding moisture to it, the peat moss turns hydrophobic. This means it repels the moisture if you try watering it.

The best solution is to prevent this problem from happening in the first place. Make sure you follow a consistent watering schedule for your plants.

If you don’t have the time you can invest in a drip irrigation system with a timer or use self-watering containers for your plants.

Heat

If your potted plants are out in the garden where there is a lot of heat, it will cause the soil to dry out and turn hard.

This will happen even if you are providing plenty of water to the potting soil but the heat is harsh during summer.

This is especially a problem if the potting soil contains a lot of clay. Maybe you are using garden soil or a mixture of garden soil and potting soil.

Garden soil tends to contain clay and depending on the amount of clay present, it will cause the soil to compact and dry out.

You should make sure your plants are getting plenty of water, especially in summer. It’s good to add a layer of mulch on top of the potting soil.

The mulch is organic material such as wood chips, grass clippings, hay, or dried leaves. This layer ensures the moisture stays in the potting soil longer. It also helps regulate the temperature of the potting soil.

Too much clay

If you use garden soil for your potted plants, you may face the problem that it contains a lot of clay. When you water the clay and it dries out, it compacts and blocks the air pockets.

This turns the soil hard and the next time you try to water the potting soil, it will just run out from the sides.

That’s why I don’t recommend you use garden soil as potting soil. You want to buy potting soil that is made specifically for growing potted plants.

This potting soil does not contain clay. But it contains materials that ensure the soil texture is good to absorb moisture.

Compaction

As you keep watering the potting soil over several months, the soil can get compacted. This can also happen if the plant is outdoors and there is plenty of rainfall.

The best thing you can do is to periodically loosen the potting soil similar to what you would do to garden soil. You can take a fork or chopstick and just poke it into the potting soil to loosen it.

Make sure you don’t damage the plant roots or stem when you are loosening the potting soil.

Age of the soil

You may have bought potting soil and some of it may not be needed. So you stored the bag for later use. The longer you keep the potting soil, the higher the chances it will become hydrophobic.

This is the main problem of peat moss as we have already seen. The peat moss needs moisture periodically so it can remain hydrophilic and absorb moisture.

If the peat moss remains without water for a long time it will turn hydrophobic and not be able to soak the moisture well.

The other problem with keeping the potting soil in a bag for a long period of time is it will compact and turn hard.

I suggest you only buy enough potting soil that you need for your plants. You can always buy more later on as you need.

If you already have extra potting soil and it has hardened, you can take some steps to loosen it. Mix in water in the bag with the potting soil and leave it in the sun for a day.

I also recommend you don’t reuse the potting soil once the growing season has ended. You can dump the old soil in your compost pile, use it as a filler in large pots, or throw it away. Buy new potting soil that is fresh and can retain moisture for the plant.

Salt buildup

If you’re watering your potted plants with tap water, there is a chance that it contains some amount of minerals and salts.

Over a period of time, these materials will build up in the soil and close up the air pockets. This will make the potting soil compact and hard.

You should leach the unwanted salts out of the potting soil every few months. This is easy to do as you just need to water the potting soil till it drains out from the bottom. Do this 2-3 times to ensure the salts are drained out of the potting soil.

At the end of the growing season, you can invest in new potting soil rather than trying to reuse the old that may be saturated with unwanted salt and mineral deposits.

How to loosen the potting soil and make it soft

The methods you can use to loosen the hard potting soil depend on whether the potting soil is just placed in a bag or you are growing plants in it.

If the potting soil is in a bag

Method 1:

You can pour some water into it and leave the bag in sun for a day. This will help loosen the potting soil while adding moisture to it.

Method 2:

Another method to loosen the potting soil in the bag is to mix in some soapy water in it. You can add a little dish soap to water and mix it until you see suds.

Pour this soapy water over the potting soil and leave it for a day. This should help loosen it up.

If the potting soil is used to grow plants

Method 1:

Take a fork and gently poke it into the soil so you can loosen it up. Make sure you’re not damaging the plant stem and roots in the process.

This is a little time-consuming method but it will help get the potting soil turned over so it can start absorbing moisture again.

Method 2:

If you can lift the pot, then place it in a tub filled with water. If there are air pockets in the potting soil, it may float and you need to push it inside the water.

You will see air bubbles coming out as the water starts filling the air pockets. Once the pot is submerged in the water, leave it there for an hour. Make sure not to keep it there for more than a couple of hours.

After an hour take the pot out of the tub and place it in a shallow container filled with water. Keep it in this container for another hour. The potting soil will absorb the moisture from the drainage holes at the bottom.

This will help ensure that the potting soil has absorbed the moisture and loosed itself back again.

Method 3:

If the pot is large and you cannot lift it, you can leave a garden hose with a little water dripping out from it on top of the soil.

The slow trickle of water will get absorbed in the potting soil over time and ensure that it gets back its moisture-absorbing properties.