It’s nice to grow plants and vegetables in a wood planter box. Especially when you have limited growing space.

But it’s important to clean the wood planter box sometimes. This could be before the start of the growing season every year.

The cleaning of the planter box will help make it last longer and also look attractive. It will help protect the plants from unwanted pests or diseases that may have found their way into the potting soil.

In this post, I’ll help you with steps to clean your wood planter box. I’ll also provide tips to remove mold and keep it away. And protect your wood planter box from rotting.

Let’s get started.

How to clean wood planter box?

Materials required to clean the wood planter box

  • 5-gallon bucket
  • Clean water
  • Toothbrush
  • Old rags
  • Bleach
  • Gloves
  • Mask
  • Eye protection

Precautions to take before cleaning the wood planter box

If you’re sensitive to chemicals, use protection for your hands and face. You can wear gloves when cleaning the planter box.

Use eye protection and wear a mask so the chemical fumes don’t cause breathing problems. Keep some old rags handy in case you spill the solution.

It’s best to clean the wood planter box outdoors where there is good ventilation because you’ll be dealing with chemicals.

I conducted a poll with fellow gardeners on what they use to clean their wood planter box. Surprisingly, 57.1% were OK with using just water to clean it. My view is that they were cleaning it often and had no issues. But if left for a long time, the planter box would need some thing strong like bleach to clean and sterilize it. Below are the poll results shown in the image.

Clean the wood planter box

The first step is to remove dirt from the wood planter box. Add 1 part bleach and 9 parts water to the 5-gallon bucket.

Use enough to create a solution that you can apply to the entire wood planter box.

Pour some of the solution on one side of the wood planter box. Use the toothbrush to scrub any dirt and residue from the wood.

Repeat the same process again on each side of the planter box. Cover the inside and bottom. This process will help remove all the dirt from the wood.

First, empty the planter completely. Using a thick stiff brush, brush it clearly. Then again, with the brush, warm water, and some liquid detergent, scrub the inner areas as well as the outside of the planter neatly. Don’t forget to clean the troughs, trays, or saucers, if there are any. If the planter faced any problems with diseases or it has mold, make a 10% beach solution, and soak the planter in it. Finally, rinse it properly with clean water. Remember to give it enough time for drying and only then put fresh new soil into it for replantation.  – June Griffith, Founder at Garden Furniture

Once all the sides of the planter box are covered with the solution, leave it to dry outdoors for at least an hour. The bleach solution will help sterilize the planter box and kill most of the germs, bacteria, and fungi.

Then you can use fresh water to clear the bleach solution off the wood planter box. Give it a good rinse so no bleach comes in contact with your plants later.

Keep the planter box outdoors until it completely dries off. Then it is ready to put the potting soil and grow plants.

How do you get mold out of wooden planters?

The wooden planter box may get mold because of overwatering and moisture collected at the bottom. The lack of sunlight and humid conditions is ideal for the mold to grow.

Get rid of the mold from the wooden planter

It’s easy to get the mold out of wooden planters as part of the cleaning process. Just keep the planter out in bright sunlight for a day. The heat and dry weather will kill the mold.

If you don’t have such weather, you can get rid of the mold using natural fungicide. The above method of using bleach and water will work to kill the mold as well.

Mix one part bleach with 9 parts water. Use a toothbrush to scrub the solution into the wooden planter where mold is growing.

Keep the planter outdoors or in a well-ventilated area for at least an hour. This will get rid of the mold. You can then clean the wood planter with water.

One of the best natural cleaners for wooden planter boxes is white vinegar. Mixing it with equal parts water and a cap or so of dish soap and scrubbing the box thoroughly will result in a mild but effective clean. This will also remove and kill any mold growth. To prevent wooden planters from rot, try using planter stands to give moisture somewhere to go, or liners within the box so soil doesn’t sit directly against it. – Andre Kazimierski, CEO, Improovy

Prevent mold from growing in the wooden planter

The best way to prevent mold from growing on wood is to keep it clean and free from excess moisture. Lining the planter box with a plastic liner can help a little.

But the best solution is to prevent overwatering the potting soil. Make sure there is good drainage in the planter box. Use drainage holes at the bottom and, if possible, elevate the planter box for the water to drain out well.

Applying a sealer inside the wood planter is also a good option to keep mold away. Use the method above with a solution of linseed oil and mineral spirit.

Apply it well inside the planter box and let it dry for a few days before you add the potting soil.

How do you keep wooden planter boxes from rotting?

Materials required

  • 1-gallon bucket
  • Paintbrush
  • Old rags
  • Pure raw linseed oil
  • Mineral spirit
  • Gloves
  • Mask
  • Eye protection

Precautions to take before sealing the wood planter box

If you’re sensitive to chemicals, use protection for your hands and face. You can wear gloves when applying the solution.

Use eye protection and wear a mask, so you’re protected if the solution splashes on your face. Keep some old rags handy in case you spill the solution.

It’s best to seal the wood planter box outdoors or a location that has good ventilation.

Seal the wood planter box

Sealing will make the wood planter box water-resistant. It will prevent rotting and provide some protection from the harsh weather.

Make sure that the wood planter box is clean following the steps that I mentioned above. Ensure that the planter box is dry.

Mix a 50:50 solution of the pure raw linseed oil and mineral spirit in the 1-gallon bucket. The linseed oil will seal the wood. The mineral spirit helps the linseed oil thin, so it is easy to apply. Stir the solution well, so both are mixed.

Use the paintbrush to apply the solution on all sides of the wood planter box. Apply inside and bottom of the planter box. Apply along the grain of the wood.

 The wood will absorb the solution well and you need to leave it to dry for a few days. Once the solution has dried, your wood planter box is ready for the potting soil and plants.

You can make an easy DIY cleaning solution with just two ingredients – bleach and water. After dumping all of the dirt and debris out, take a hard-bristle brush and scrub the planter to remove the majority of the dirt and grime that has hardened or gotten into the cracks of the planter. Then, take your solution and spray it all over, allowing it to sit and soak for around 30 minutes. After that, rinse out the planter with water and scrub again, allowing it to fully air dry when completed. – Jeremy Yamaguchi, CEO, Lawn Love

Ensure good drainage in the planter box

The major problem that causes rotting in the wood planter box is poor drainage. This can happen for several reasons, but they are simple to prevent.

Ensure that your planter box has sufficient drainage holes at the bottom. These help excess water drain out that would otherwise collect and cause the wood to rot.

Your wood planter box may rot even with drainage holes. Check those holes have not clogged up because of the potting soil. The drainage holes should be large enough for the water to pass through.

I would suggest adding a layer of organic material at the bottom of the planter box. This material helps keep some space between the potting soil and the drainage holes. And helps the excess water drain out with ease.

Applying an extra protective coating to your wooden planter box prevents it from rotting. Brush about 2-3 layers of plant-safe, non-toxic, and water-repellent paint on the surface. It will seal off any micro-crevices where the molds can potentially enter and start decomposing the wood. Mineral oil or water-based latex paint are excellent choices for preserving timber. – Melvin Cuban, PlantIn expert

You can use material such as dried leaves, newspaper, straw, hay, or wood chips. You could even use material such as terracotta pot pieces, milk cans, or packing peanuts.

Some times the problem with drainage happens because the bottom of the planter box is touching the grass or concrete floor on the bottom. The water does not get sufficient space to drain out.

My suggestion is to elevate the wood planter box so it can help with the draining. You can choose a planter box that comes with elevation.

Or you can use materials such as pot feet, wine cork, concrete blocks, bricks, or wood planks to raise it above the ground.

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