How To Keep Your Concrete Planters From Cracking

It’s fun to make your own concrete planters, and there are tons of DIY designs you can find online. However, concrete is prone to cracking, wamazhich can happen for several reasons. You’ll want to know precisely what they are to prevent any other ones you make from cracking.

You can keep your concrete planters from cracking by using less water in the mixture and ensuring you don’t use an expired concrete mix. You might also need to bring them inside during dry weather or check that they have ample drainage.

Water can cause many problems, so you’ll want to use just enough to prepare the mix. There’s more to learn about preventing your concrete planters from cracking; you can find everything in the article below.

1. Add Less Water to the Concrete Mix

The most common reason that concrete cracks are that it has too much moisture. When preparing the concrete, it’s easy to stir in too much water. However, doing so can easily ruin your work later on. 

The water evaporates while the concrete cures, which makes the planter settle. If there is a lot of water in the concrete, it will start shrinking rapidly, leading to cracks or crumbling. These cracks are usually thin, so you should be able to fix them with a bit more concrete.

Too much water can also cause the concrete to become more porous as it cures, making it much easier for the planter to crack. Knowing how to mix the concrete precisely is essential if you want a strong planter. However, every brand may require slightly different amounts, so you’ll want to follow the instructions given to you.

Reducing how much water you add to the concrete makes a huge difference. If you followed the instructions on the mixture’s packaging and it still cracked, you’ll want to use slightly less water next time. Additives are also available that make the concrete easier to pour and make, so you don’t have to add as much water to the mix.

Since too much water is the most common problem, it’s worth addressing this issue before moving on to the others.

2. Always Check the Expiration Date

Next, you should always check the expiration date on the packaging before you mix the concrete. We tend to think concrete mix stays good forever, but expired mix is much more likely to crack than fresh. You won’t be able to get nice-looking results with it either. Plus, you’ll have an easier time mixing concrete that’s not expired, and it will last you a lot longer.

Concrete mixes contain many different chemicals and minerals, which don’t stay good forever. Eventually, they won’t bind correctly, leading to cracking. You can expect most concrete mixes to last about a year before they start breaking down.

So, if you’ve had your bag of concrete for longer, you’ll probably need a new one. The same is true if you didn’t store it in an airtight container and had the mix open for a few months.

Using an expired mix can cause severe crumbling and cracking to the planter projects. You’ll want to use a newer bag to get the best results.

3. Don’t Leave Curing Planters Out in Dry Weather

Weather conditions can also cause a lot of cracking, especially during curing. Dry air can suck all the moisture out of drying concrete, which causes cracks.

The dry, hot weather makes the water evaporate out of the concrete too quickly, making the planter shrink faster than it should. You might also notice certain areas of the pot crumbling when this happens.

The best way to avoid cracks when it’s hot out is to use water and a plastic bag to reduce drying times.

Slowing Down Concrete Drying Times

All you need to slow down concrete drying times is some water in a spray bottle and a plastic bag.

Then, follow these steps:

  1. Mist the curing concrete with water.
  2. Cover the concrete planter with a plastic bag.
  3. Check on the concrete as it cures and mists it when it feels dry.

By following this process, you can slow the drying time of your project by a few days. It’s most beneficial when quick shrinking from dry heat causes cracking. You probably won’t need to slow down drying if you live somewhere humid.

4. Give Your Planters More Drainage

Not having ample drainage can also cause the concrete planter to crack. If you haven’t sealed the inside of the planter, the water you give your plants can make its way into the porous concrete. Overwatering can be a problem, no matter what types of containers you use for your plants. 

It’s usually best to add a hole in the bottom of the planter before it cures since the concrete is softer. However, you can still add one when the concrete’s set to stop further cracking. 

How To Make a Drainage Hole

For this project, you will need a masonry drill with bits, safety goggles, and a rag.

Here’s what you need to do when you have those materials:

  1. Place the planter upside down on a rag.
  2. Put on your safety goggles.
  3. Use a small drill bit to cut through the center of the planter.
  4. Using the small hole as a guide, enlarge it with a bigger bit.
  5. You can make the hole larger again if you need to.

Starting with a small hole is essential because it prevents the planter from breaking and gives you a visual guide. In short, you’ll need to add a drainage hole if you don’t already have one. Not only will it prevent your plants from getting overwatered, but it also prevents cracking in concrete planters.

5. Seal the Concrete Planter

Sealing the concrete planter is also a good idea. Although, you need to be careful since there are certain situations where you shouldn’t seal it. You’ll need to consider what plants are going into the pot first and the soil’s pH.

Essentially, sealing your pot can lower the soil’s pH since the minerals in concrete can’t leach into the soil when wet. Many plants that like low acidity do well in sealed planters, while ones that like high acidity prefer unsealed planters.

Sealing your planter makes the concrete less porous, which means moisture won’t be able to get inside. You can significantly reduce cracking when that’s the main issue with your concrete. Sealant provides another layer of protection to your planters, which also helps with chipping and crumbling.

A seal allows you to add a pop of color to the planter, too, so many people do this to make their DIY concrete pots more decorative. Overall, sealing the planter can significantly reduce the odds of cracking.

Sealing a Concrete Planter

If you’ve decided you want to seal your concrete planter to keep it from cracking, it’s a simple process. You’ll want to find a reliable sealant first. I recommend the Black Diamond Stoneworks Sealer from Amazon.com. This option comes in an easy-to-apply spray bottle and offers your concrete good protection from moisture.

Once you have your sealant, all you need to do is coat the planter. Give the seal a few hours to dry, then apply another coat. Make sure you get the inside of the planter, too–you want to cover it with the sealant completely.

Depending on what sealant you buy, you might need to apply it with a sponge brush. After that, your concrete planter can resist moisture better than before.

How To Repair Cracks in Cement Planters

If your DIY concrete planters already have a few small cracks, you might not need to throw them away. It’s better to try repairing them first. You will need concrete mix (preferably the same kind you used to make the planter), a trowel, and some pieces of cloth.

Here’s what you can do once you have everything:

  1. Clear the plant and soil from the planter. You’ll need to put them in a temporary pot.
  2. Clean the inside of the planter with water.
  3. Clean the cracks and remove any debris.
  4. Let the planter dry while you mix the concrete.
  5. Apply the concrete using a trowel or knife, and fill the gaps completely.
  6. Scrape off the excess concrete.
  7. Dip the cloth pieces in water, then wrap them around the planter to cover the cracks.
  8. Wait for the cement to cure and remove the cloth strips.
  9. Apply a seal to the planter.

Conclusion

In short, too much moisture and too little can cause problems with concrete. You’ll need to add enough water to the concrete mix, then let it completely cure before adding the soil and plants. Before you start, it’s also a good idea to check that you’re not using an expired mix.

You may want to bring the planter inside when the weather conditions can cause cracking. Finally, give your pots ample drainage so moisture can’t build up in the concrete. If you do all this, your planters will last many years.

Alexander Picot

Alexander Picot is the principal creator of TheGrowingLeaf.com, a website dedicated to gardening tips. Inspired by his mother’s love of gardening, Alex has a passion for taking care of plants and turning backyards into feel-good places and loves to share his experience with the rest of the world.

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