Should you line wooden window boxes?

Lining wooden window boxes can provide a number of benefits that make it worthwhile for many gardeners. In this article, we’ll go over the pros and cons of lining window boxes to help you decide if it’s the right choice for your gardening needs.

What is a window box liner?

A window box liner is a protective barrier that is placed inside a wooden window box before filling it with soil and plants. Liners are commonly made from plastic, coconut fiber, moss, or foam. The purpose of a liner is to protect the wood of the window box from rotting prematurely due to excess moisture exposure.

Without a liner, the constant wetting and drying of the wood from watering plants can cause the wood to warp, split, and rot over time. This can lead to leaking, cracking, and eventual failure of the window box. Liners prevent this by acting as a moisture barrier between the damp soil and the wood structure.

Benefits of using a window box liner

There are several reasons why lining a wooden window box is recommended:

• Protects wood from rotting – As mentioned, liners prevent premature wood rot by limiting moisture exposure.
• Extends life of window box – By protecting the wood, a liner helps the window box last many more years before needing replacement.
• Prevents leaks and cracks – Liners reduce leaks through cracks and holes by containing moisture inside.
• Allows for good drainage – Many liners provide space under the soil level to allow for drainage holes without risk of rotting the wood.
• Easier to keep clean – With a liner, old soil and roots can be easily dumped out for fresh soil each year.
• Aesthetically pleasing – Liners come in various colors and materials that can complement your window box’s appearance.

The main takeaway is that adding a liner to your wooden window box will help protect your investment and allow you to get years more use out of the box before needing to replace it.

Potential drawbacks of liners

There are a few potential drawbacks to keep in mind when deciding on a liner:

• Added upfront cost – Purchasing a liner adds immediate cost to your project budget.
• May reduce interior volume – Some liners take up space inside the box, reducing the soil capacity.
• Plastic liners lack breathability – Plastic liners may trap more moisture against the wood compared to natural fiber liners.
• Installation takes time – Properly installing a liner takes time and may require some DIY skills.
• Vulnerable to punctures – Sharp objects may accidentally puncture plastic and moss liners during installation or use.

However, many gardeners find the benefits of using a protective liner outweigh the drawbacks. The small upfront investment can lead to years of added life for your window box.

What types of liners are available?

If you decide to line your wooden window box, you’ll find there are a few common types of liners to choose from:

Plastic Liners

– Typically made of polyethylene or vinyl
– Often molded to fit window box shape

– Available in various colors to match décor

– Can last many years if intact
– Lowest cost option

Coconut Fiber Liners

– Created from coconut husks
– Biodegradable and eco-friendly
– Absorbent to retain some moisture
– Natural appearance good for rustic look
– Need replacing every 2-3 years as fibers break down
– Moderately priced

Sphagnum Moss Liners

– Made from dried sphagnum moss

– Retains moisture well for plants
– Provides insulation to protect roots
– Natural green color blends into garden
– Needs replacing every 1-2 years
– On the higher end of cost

Foam Liners

– Made from polystyrene foam
– Extremely lightweight
– Easy to cut to size
– Provides insulation for roots
– Cheapest option but not very durable
– Tears easily and degrades over time

Key considerations when choosing a liner

Here are a few key factors to consider when selecting the right window box liner for your needs:

• Durability – How long will the liner last before needing replacement? Plastic and coconut fiber liners will outlast sphagnum and foam.
• Drainage – Make sure the liner provides adequate holes or space for drainage to prevent soil from getting waterlogged.
• Moisture wicking – Consider whether the liner will trap excessive moisture against the wood. Plastic sometimes causes more moisture buildup than natural fibers.
• Aesthetics – Choose a liner color and material that complements your window box’s visual style.
• Cost – Plastic and foam liners are cheaper upfront than coconut and sphagnum fiber.
• Eco-friendliness – Coconut fiber and sphagnum moss are biodegradable and renewable options.

Take all of these factors into account when deciding which type of liner makes the most sense for your gardening needs and budget.

How to install a window box liner

Installing a liner is a relatively straightforward process, though the exact steps may vary slightly depending on which liner type you select:

1. First, thoroughly clean and dry the window box interior to remove any dirt, debris, or old roots and soil.
2. For plastic liners, trim the liner to fit the dimensions of your box, leaving an extra inch or two for coverage.
3. For other liners, cut pieces to size and layer them to cover the bottom and sides of the box interior.
4. Place the liner pieces into the box, pressing firmly into each corner and against the sides.
5. For plastic liners, you can optionally staple or nail around the top edge to firmly secure the liner in place.
6. Ensure drainage holes align between liner and box, trimming liner if needed.
7. Fill box with quality potting soil up to about 1 inch below the rim.
8. Water thoroughly after planting to settle the soil. Check for leaks at this point.

The installation process takes less than an hour in most cases. Having the right liner measurements and using care when positioning the liner are key to getting a smooth fit.

Tips for making liners last longer

Here are some tips to help extend the usable lifespan of your window box liner:

• Inspect periodically for leaks, tears, or deterioration.
• Avoid sharp gardening tools when digging around plants.
• Remove and rinse out liner annually when refreshing soil.
• Use coarse sand or gravel under soil to prevent root punctures.
• Choose a durable liner type like thick plastic or multilayer coconut fiber.
• Keep soil level a few inches below the liner rim to minimize overflow.
• Reapply weatherproofing annually for wood window boxes.

Taking steps to protect the liner and wood box from damage will help maximize the number of seasons you can use the liner before replacing it.

FAQs about window box liners

Why shouldn’t you use landscaping fabric as a liner?

Landscaping fabric is too thin and porous to adequately protect a wooden window box. The small pores will allow soil and moisture to penetrate through to the wood. A liner needs to fully block moisture and root penetration. Plastic, coconut fiber, moss, or foam liners are much better suited for this application.

Can you use a liner in a plastic window box?

Lining a plastic window box is generally not necessary since plastic does not rot from moisture like wood does. However, some gardeners still opt to use liners in plastic boxes to make the inside surface smoother, retain moisture, insulate roots, and make seasonal soil replacement easier.

How long do liners last?

The lifespan of a window box liner depends on the material used:

• Plastic liners typically last 4-6 years.
• Coconut fiber liners last 2-3 years before needing replacement.
• Sphagnum moss liners may only last 1-2 seasons.
• Foam liners often need replacing annually.

Harsh weather, intense sunlight, improper drainage, and objects puncturing the liner can shorten its usable life. Taking steps to protect and care for the liner can help maximize its durability.

Can you grow vegetables in a lined window box?

Yes, it is certainly possible to grow vegetables like lettuce, kale, carrots, bush beans, and more in a properly lined window box. The key is to make sure the liner provides adequate drainage to prevent oversaturation of the soil. Adding a layer of gravel at the bottom can improve drainage for vegetables. As long as the box gets sufficient sunlight and the plants are watered consistently, many vegetable crops can thrive in a lined box.

Conclusion

Installing a protective liner inside your wooden window boxes provides benefits that usually outweigh the small upfront cost and effort. Liners extend the usable life of your window boxes, prevent rotting and leaks, and make seasonal planting easier. Choose plastic, coconut fiber, sphagnum moss, or foam liners based on your budget and gardening needs.

Carefully install the liner and take steps to keep it intact over time. With proper use and care, a liner can protect your wood window box for many years, saving you the cost and hassle of frequent box replacements. If you want to grow vibrant flowers or tasty vegetables in attractive window boxes, adding a high-quality liner is strongly recommended.