How to Fill the Bottom of a Large Planter Without Compost – Save Money and Effort With This Simple Trick

Filling the bottom of a large planter with lightweight, low-cost materials is an easy way to use less compost, cut costs, and reduce weight, without compromising on plants. Instead of packing the entire container with potting soil, you can layer the base with alternative fillers to make planting more efficient and lower effort.

Large planters can make a dramatic statement, whether flanking your front door or acting as a focal point in a garden scheme. But that impact often comes with a downside: they require a significant volume of compost and can become extremely heavy once filled.

The good news is that you don’t need to fill the entire container with soil. Most plants don't need it, and so by using different materials in the base, you can reduce how much compost you need and, in some cases, make the planter easier to move, depending on what you choose and how you intend to use it. Good drainage in a planter is still essential, so make sure yours has adequate holes. Beyond that, what you use to fill the bottom isn’t arbitrary. From practical to budget-friendly options, there are several smart materials that can do the job effectively, and this guide explores the best ones to consider.

Lightweight Options to Fill the Bottom of a Large Planter

If you want large planters that can be moved elsewhere in the yard or indoors (such as this beautifully versatile cream fiberstone container from Amazon), it is beneficial to add lightweight materials.

Whether you need to move the planter to overwinter plants indoors or relocate it to the sunniest spot in the yard, reducing the weight makes it easier.

The following materials are great light materials to use to fill the bottom of a large planter:

• Pine cones
• Sticks
• Plastic pots
• Styrofoam/packing peanuts
• Plastic bottles/milk jugs
• Wood chips
• Bubble wrap
• Cardboard

Heavyweight Options to Fill the Bottom of a Large Planter

There are reasons why you may want to keep the planter heavy, but not by spending lots of money filling it with potting soil for container gardening.

Also, filling a large planter with pure soil increases the risk of waterlogging, even when you have drainage holes, due to compaction, and plants can suffer from root rot.

For example, if you have tall trees or plants in large decorative pots, such as this large rustic weathered white planter from Wayfair, extra weight at the bottom of a large planter can prevent it from tipping over in high winds.

And if your large planters are permanent installations in your backyard, these larger materials can fill the space and ensure that the containers will not go anywhere:

• Logs
• Broken pottery
• Rocks
• Bricks
• Gravel

How to fill the bottom of a planter

As you fill the bottom of a large planter, take care not to block the drainage holes. Good drainage is essential for healthy roots, so avoid placing heavy, dense materials, such as rocks or bricks, directly over the holes, as these can prevent excess water from escaping.

This is a common container gardening mistake and can quickly lead to waterlogged compost and root rot.

Instead, opt for lighter, more permeable materials that allow water to move through easily. If you’re using plastic items, such as bottles or containers, adding a few holes will help improve drainage and prevent water from pooling at the base.

When layering your planter, aim to fill roughly the bottom third with your chosen material. While you don’t need to fill the entire container with soil, plants still require enough depth for their roots to establish.

Leave several inches of compost beneath the root ball to allow for growth and proper moisture distribution. Raising the water table too high can reduce airflow around the roots and increase the risk of rot.

You can add a liner, such as landscape fabric, available from Target, or even old compost bags, over the filler layer to keep soil separate. This step isn’t essential, but it can help prevent compost from filtering down over time.

If you do use a liner, make sure it’s permeable so water can drain freely through the container.

Finally, it’s worth knowing that there are some materials you should never use to fill the base of a planter; some can do more harm than good.

Shop Planting Essentials

A lot of focus often goes on annual flowers in containers to provide those quick hits of summer color. However, there are lots of evergreen plants that can add interest year-round when growing in pots.

Our guide to the best plants for pots all year round includes evergreen shrubs, small trees, and perennials that can be used for dazzling displays in large planters that look good for a full 12 months.

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