7 Best Waterproof Liners For Planter Boxes (How to Use)

By   | Last Updated :   October 29, 2021 | Filed In :   DIY & How To

Protect Your Planter Boxes with Waterproof Liners

Waterproofing your planter boxes is essential for extending their life and ensuring healthy plant growth. Whether you have a wooden or metal planter box, choosing the right waterproof liner can make a significant difference. Here’s an easy-to-follow guide on the options available and how to apply them.

A woman tending to flowers in her lined wooden planter box

What is a waterproof liner?

Waterproof liners are designed to protect your planter boxes from moisture. They come in various materials, primarily plastic, and are essential for preventing wood rot and metal corrosion. Options range from plastic containers and sheeting to spray-on solutions.

Types of waterproof liners for planter boxes

If you want to line your planter box, your first step is to choose a liner. As there are so many to choose from, we’ve created a list of the most popular planter box liners and how you can get started:

1. Plastic pots

Plastic pots are a convenient liner option as they can be placed inside other containers like your wooden planter boxes. This way, you can remove the whole container when you need to water your plant and return it to the planter box afterwards. If done correctly, your planter box will never be in contact with water, making it last a very long time.

Stallion 10cm x 27cm x 13cm Brown Rectangle Rattan Planter Case Box

Check Latest Price »
We may earn a commission if you make a purchase, at no additional cost to you.
  Pros Cons
  • Easy to use and move
  • Keeps planter boxes dry
  • Reusable
  • Limited sizes and shapes
  • May not fit perfectly into all planter boxes

How To

2. Plastic sheeting

Plastic sheeting is a good option if you want something more permanent. Staple or glue it onto the inside of your planter box. Just remember to create drainage holes in the plastic. Most plants will rot and die if left to stand in water for too long.

plastic liner

Prolong the life of a wooden planter with plastic lining. Image credit: London Stone

  Pros Cons
  • Customizable to fit any planter size
  • Inexpensive
  • Durable
  • Requires manual installation (cutting, fitting)<br>-
  • Potential for tearing over time

How To

3. Resin

It’s surprising, but it’s actually possible to waterproof planter boxes by lining them with a cloth dipped in resin. As the resin dries, it will create a sealed layer that will protect your planter from moisture.

succulents in a planter box

  Pros Cons
  • Creates a durable waterproof barrier
  • Resistant to rot and decay
  • Messy application process
  • Requires drying time

How To

4. Fibreglass

This method is a bit more complicated and more dangerous for non-professionals. However, if you know what you are doing, Fibreglass will create a great finish that will protect your planter from moisture. Fibreglass can be dangerous if inhaled or touched while working with it, so ensure you have the proper safety equipment and training.

  Pros Cons
  • Strong and long-lasting protection
  • Aesthetically pleasing finish
  • Complex installation
  • Health risks during application (irritation, inhalation hazards)

How To

5. Pond liner

A pond liner is another great option for lining planters however, it can be quite difficult to work with. Don’t forget, once you have lined your planter box ensure there are drainage holes to keep your plants healthy.

Swell UK 4.5m x 6m Pond Liner (25 Year Guarantee)

Check Latest Price »
We may earn a commission if you make a purchase, at no additional cost to you.
  Pros Cons
  • Flexible and durable
  • Suitable for large or oddly shaped planters
  • Difficult to cut and fit precisely
  • Requires creating drainage holes

How To

6. Varnish

Varnish is another effective way to protect wooden planters. Paint the required coats, and you’re good to go.

Rustins Quick Dry Varnish Clear Gloss 250ml

Check Latest Price »
We may earn a commission if you make a purchase, at no additional cost to you.
  Pros Cons
  • Enhances wood’s appearance
  • Easy to apply
  • Provides moisture resistance
  • Frequent reapplication needed
  • May not provide complete waterproofing

How To

7. Spray-on liner

It is possible to get spray on plastic or silicone liners for planters. If you choose this option, you must prepare your planter before spraying on the required amount of liner. This type of liner does well when used to protect wooden boxes, making them last much longer.

  Pros Cons
  • Easy to apply
  • Even coverage
  • Quick drying
  • Limited durability compared to other options
  • May require multiple coats

How To

8. Fibre liners

And lastly, it might be worth checking out fibre liners. These are ideal for planter boxes and hanging baskets. While not 100% waterproof, they are great for lining planter boxes and flower pots with drainage.

10m Bulk Roll Co-Co Hanging Basket Liner (0.75m wide)

Check Latest Price »
We may earn a commission if you make a purchase, at no additional cost to you.
  Pros Cons
  • Natural look
  • Allows for air and water circulation
  • Not completely waterproof
  • May decompose over time

How To

Why you should line your planter boxes

Lining your planter boxes with the appropriate materials can vastly improve their durability and the health of your plants. From keeping the soil’s moisture balanced to preventing damage from constant water contact, the benefits are clear. Whether you opt for a simple plastic pot or a more durable solution like fibreglass, the right liner can make all the difference in your gardening success.

Improved durability

Moisture is a primary factor in the degradation of wood and metal used in planter boxes. According to research, wood exposed to constant moisture can suffer from fungal decay and structural weakness. Liners act as a barrier, reducing direct contact with moisture and significantly extending the life of planter boxes made from susceptible materials like wood and metal.

Healthy plants

The balance of moisture is crucial for plant health. Proper moisture levels can greatly affect plant growth, stress resistance, and overall health. Liners help maintain consistent soil moisture levels, preventing both over-watering and under-watering. This is particularly beneficial in climates with variable weather conditions, ensuring that plants receive a stable amount of water.

thirsty plants in a lined planter

Thirsty plants will thrive in a lined planter. Image credit: @savoredjoy

Less rot

Wood rot is primarily caused by fungi that thrive in moist environments. Using a waterproof liner, the internal environment of the planter box is kept drier, significantly reducing the risk of wood rot. This protection is crucial for organic materials like wood, which are particularly vulnerable to moisture-related deterioration.

More planter options

Experts in horticulture recommend diversifying planter materials for aesthetic and functional garden design. A report by the University of Georgia Extension highlights the benefits of using various planter materials to suit different plant needs and design aesthetics. By using liners, gardeners can safely use a broader range of materials, including those not naturally suited to outdoor or moist environments, without risking damage from water exposure.

Lining Your Planter Box

Lining your planter boxes provides tangible benefits backed by scientific research and expert recommendations. From prolonging the lifespan of your planters to ensuring healthier plant growth, using liners is a validated practice that addresses several key challenges in gardening and planter maintenance. This approach allows gardeners to enjoy more versatile, durable, and effective planting solutions, contributing to a more sustainable and vibrant gardening experience.


Does a wooden planter box need a plastic liner?

Yes, wood planters will last much longer when lined with plastic. Plastic liners prevent moisture from being in constant contact with the wood. This in turn prevents the wood from rotting prematurely.

How do you waterproof a planter box?

How depends on the liner. If it’s a pot, simply place it inside the planter of your choice, if it’s plastic sheeting either glue or staple it in place. If you decide to rather go for the liquid version, you can either paint or spray paint it on.

What should I line the bottom of a planter with?

To prevent soil from falling out, you can place coffee filters or fine wire mesh over the drainage holes. You can also use a newspaper or cheesecloth for this purpose.

Can I use multiple types of liners together for extra protection?

Yes, combining liners can offer additional protection. For example, using a plastic sheet beneath a resin coat can provide double the moisture barrier. However, ensure compatibility between materials to avoid any adverse chemical reactions or the trapping of moisture between layers, which could lead to rot.

How often should I replace the liner in my planter box?

The lifespan of a liner depends on the material used and the conditions it’s exposed to. Plastic sheeting and pots might last several years, while resin and varnish may require inspection and potential reapplication every 1-2 years. Regularly check your liner for signs of wear or damage and replace as necessary.

Are there eco-friendly options for waterproofing planter boxes?

Yes, for those seeking sustainable solutions, consider using liners made from recycled materials or natural fibers. Although they might not offer the same level of moisture protection as plastic, they are better for the environment. Additionally, natural varnishes and eco-friendly spray liners are available in some markets.

Can I waterproof my planter box without using liners?

Yes, using naturally rot-resistant woods like cedar or redwood can reduce the need for a liner. Additionally, applying a sealant directly to the wood can offer some degree of water resistance, but this may not be as effective as using a liner.

How do I ensure proper drainage in my lined planter box?

Proper drainage is crucial to prevent root rot. When installing your liner, ensure you create enough drainage holes at the bottom. If using plastic sheeting or pond liner, puncture evenly spaced holes. For pots and containers, choose ones with pre-drilled holes, or add them if necessary.

Will a liner affect the temperature or moisture level inside the planter box?

Liners can impact the microenvironment within your planter. Plastic liners can reduce soil aeration and trap heat, which might be beneficial in cooler climates but problematic in hot ones. Choosing a breathable liner like natural fiber can help maintain better air and moisture balance.

Is it possible to install a liner in an already planted planter box?

Installing a liner in a planter that’s already in use is challenging but possible. For less invasive methods, consider using spray-on liners or applying a thin layer of resin. These options can offer protection without the need to remove and replant. However, the most effective method might involve replanting to ensure the liner is properly installed.

You might like: What can I plant in a flower box?

7 best waterproof liners for planter boxes (how to use)-min

Save this pin for later

Post Tagged:
  1. Sarita
    February 27, 2023 at 6:44 pm

    I would love to know which linings are the safest for growing vegetables, from a microplastics and toxicity point of view.

    • Liz Berry
      June 6, 2023 at 11:50 am

      Hi Sarita, this is a good point and it’s tricky to find a waterproof lining that doesn’t contain plastic. I personally use coco liner, it’s made from natural coconut fibre and is really long lasting as well as food safe.


Leave a Reply

Your email address will not be published. Required fields are marked *