Weeds are one of the pain points that every gardener faces when growing plants. Potted plants have fewer chances of growing weeds, but they still can.

Weeds can grow in potted plants because the seeds can reach the potting soil from birds, animals, poor compost, poor soil, and even neighboring plants. The best solution is to remove the weeds by hand. You can prevent weeds by taking precautions that keep the potting soil sterile.

I’ve written all the information you need to understand why weed can grow in your potted plants. I’ve also provided solutions that will help you eliminate weeds and prevent them from reaching your pots in the first place.

Why do weeds grow in potted plants? And how to prevent them

Seeds dropped by birds and animals

Birds and animals visiting your potted plants are probably the most common reason weeds reach the potting soil.

The seeds that stick to the bodies of the creatures drop into the soil and germinate into weeds.

The best way to prevent this problem is to keep the birds and animals away from your potted plants. You can do this using netting that prevents them from coming in contact with the plants.

You could use a garlic spray on the potting soil to prevent some of the creatures because of the smell. It will also keep some pests and diseases away from the plants.

Using compost that has weed seeds in it

I like using compost because it provides nutrients and beneficial organisms to the potting soil. The problem is that compost may contain weed seeds that will germinate once added.

The best way to prevent this problem is to use compost taken from a heated compost pile. This means the temperature in the compost pile has reached at least 120 degrees Fahrenheit.

This temperature will kill most of the weed seeds and prevent them from germinating when added to the potting soil.

If you have bought compost from the store, you may not be able to find this out. Some compost manufacturers may certify their compost is weed-free.

Using soil that has weed seeds in it

The soil that you use can introduce weeds to the potted plants. This is common if you use garden soil that most often contains weed seeds.

The weeds could also reach the potted plants through cheap potting soil that has not been sterilized and contains weed seeds.

I recommend spending a little money but buying high-quality potting soil that will have fewer chances of growing weeds. Some manufacturers certify that their potting soil is sterile and free from weeds.

You could also sterilize the potting soil by heating it to 120 degrees Fahrenheit in the oven for an hour.

In most climates, depriving weeds of water reduces weed-seed germination by 50 to 70 percent. (finegardening.com)

Using pots without sterilizing them

You may buy new pots or reuse existing ones to grow potted plants. These pots may contain weed seeds that would then be introduced to the plants.

I recommend sterilizing the pots before using them to grow plants. This will get rid of weeds as well as any pests and diseases in the pot.

The easiest way to do this is to soak the pot in a bleach solution for an hour. You mix 9 parts bleach with 1 part water to create this solution.

Then wash the pot well with clean water and let it dry out in the sun. Then the pot is ready to add potting soil and grow plants.

Buying poor quality seeds

Weeds could get introduced to your potted plants because the seed packets themselves contain the weeds.

You need to buy your seed packets from a trusted company that would ensure the high-quality and lower the possibility of weeds.

Buying transplants that are not sterilized

You may germinate seeds in pots or buy the transplants directly from a local garden center or nursery. If the transplants have not been sterilized, they may contain weed seeds.

You need to ensure the transplants are from a good source that will grow them in a controlled environment protected from weeds.

If you are buying transplants from a local nursery, ask them to identify the source. This will give you an idea about the quality of the transplants.

How to use mulch to prevent weeds in potted plants?

Even with all the precautions you take, there could be weed seeds reaching your potted plants. Mulch is a good solution to smother such weeds before they germinate.

Mulching is the process that uses organic matter such as dried leaves, grass clippings, wood chips, hay, or straw to cover the soil surface. 

The benefit of using mulch is that it will block sunlight from reaching the weed seeds. This would keep the seeds from germinating and growing into weeds.

You should add mulch only after the potted plants have germinated and grown a few inches tall. 

I recommend adding a layer of newspaper on top of the potting soil before adding the mulch. Spread 2 inches of the organic material on top of the newspaper. Make sure that it does not touch the base of the plant.

The added benefits of mulch are insulating the potting soil, so the temperature is regulated. This means you don’t need to water the potted plants as often.

The organic mulch will also break down over time and add nutrients and beneficial organisms to the potting soil.

How to get rid of weeds from potted plants

Pull the weeds out by hand

The best solution to get rid of weeds is to pull them out by hand from the potting soil.

I recommend you check on your potted plants every morning for weeds, pests, and diseases. Pull the weeds out as soon as you see them germinated from the soil.

It’s easy to pull the weeds out when they are small, and they will come out along with the roots. Water the potting soil, so it’s easier to pull them out. Gently shake the weeds and pull them out of the soil.

If the weeds grow larger, they may become strong, and you may not be able to pull them out without damaging the plant’s roots. Then you would need to use a pruner to cut the weed at the base while keeping the roots.

Make sure to wear gardening gloves before pulling out weeds because some could be toxic or contain thorns.

A noxious weed, harmful weed or injurious weed is a weed that has been designated by an agricultural or other governing authority as a plant that is injurious. (wikipedia.org)

Add mulch on top of the potting soil

I already showed you the method to use mulch and prevent weeds from germinating in the potting soil.

You can also use mulch to get rid of weeds that have germinated in the potting soil. Cover the potting soil with a layer of newspaper so it will smother the weeds.

Now add a 2-inch layer of mulch on top of the layer of newspaper, so it completely blocks the weed seeds.

You can use any organic material such as grass clippings, dried leaves, wood chips, straw, or hay as part of the mulch.

Use a natural weed killer spray

There are several organic materials you can use to create a natural weed-killing spray. I would suggest using this option only if you have many potted plants and don’t want to spend time pulling by hand.

The problem with using such a spray is you need to be careful that your plants don’t get affected by it. The spray could harm or even kill the plants if you’re not careful.

Here are recipes for some of the sprays you could make using materials available in your house.

Vinegar weed-killer spray

Ingredients

  • 1 gallon of white vinegar (5% strength)
  • 1 cup of table salt
  • 1 tablespoon of liquid dish soap

Instructions

  • Add the salt to the white vinegar in a bucket and mix it well till it dissolves. Pour 1 tablespoon of the soap into the solution. Add it to a spray bottle and spray on the weeds. They will die in a few days.
  • The liquid soap acts as a surfactant that will help the solution stick to the weeds and dehydrate them.
  • Make sure to use white vinegar as that has weed-killing properties. Spray the solution on a dry, sunny day to get the best effect.

Baking soda weed-killer spray

Ingredients

  • 1 cup of water
  • 1 tablespoon of baking soda
  • 1 tablespoon of table salt
  • 1 tablespoon of liquid dish soap

Instructions

  • Add the baking soda, table salt, and dish soap into a container and mix them well.
  • Add the solution to a spray bottle. Spray on the weeds on a dry, sunny day to kill them.

Rubbing alcohol weed-killer spray

Ingredients

  • 2 tablespoons of rubbing alcohol
  • 4 cups of water

Instructions

  • Mix the rubbing alcohol with water and add it to a spray bottle.
  • Spray it on the weeds on a dry, sunny day. The alcohol will dry out the weeds and kill them.