When it comes to planting in large pots, not every bit of space needs to be filled with soil. In fact, filling the entire pot with soil can be wasteful and unnecessary, especially when you’re planting shallow-rooted plants. Fortunately, there are several practical and creative ways to fill space in your pots while ensuring they remain functional and aesthetically pleasing.

Here’s a guide to some handy materials you can use to take up space in your pots without compromising the health of your plants.

1. Lightweight Filler Materials

If you’re working with large pots, filling the entire container with soil can make it very heavy and difficult to move. By using lightweight filler materials at the bottom, you’ll not only reduce the amount of soil needed but also make your pots more manageable.

Polystyrene (Styrofoam): Often a go-to for taking up space in pots, polystyrene is lightweight, doesn’t break down, and improves drainage. You can use polystyrene blocks or break up packaging material to fill the bottom third of your pot. Just be sure to cover it with landscape fabric or weed matting before adding soil to prevent soil from falling through.
Plastic Bottles: Reusing plastic bottles is a great way to reduce waste while filling your pots. Flattened or crushed bottles can be placed at the base of the pot, helping to lighten the load while providing good drainage.
Cans: Empty aluminium cans are another option. They are durable and won’t degrade over time. Simply place the cans in the base of the pot, either crushed or intact, and cover them with a layer of fabric before adding soil.

Tip: Avoid filling the pot with materials that will compact or decompose over time, as this can affect drainage and soil health.

2. Natural Fillers

If you prefer using eco-friendly, biodegradable materials, there are plenty of natural fillers that can be placed in pots to take up space. These materials are ideal for gardeners who prefer to minimise their use of plastic.

Wood Chips: A layer of wood chips at the base of the pot can reduce the amount of soil required. Wood chips are lightweight, and although they eventually break down, they will do so slowly enough not to disrupt the potting process.
Pine Cones: For a completely natural option, pine cones are excellent fillers. They are lightweight and will help with drainage while providing a porous layer at the bottom of the pot. Pine cones also break down slowly over time, making them a good choice for long-lasting pots.
Broken Terracotta Pots: Repurposing old or cracked terracotta pots is a great way to add drainage material while staying within the pottery theme. These pieces are sturdy, won’t compact, and provide a solid base for your plants.

Tip: If you’re using natural materials like wood chips or pine cones, it’s a good idea to check the pot every few years to ensure the materials haven’t compacted too much.

3. Perlite or Vermiculite

For gardeners looking to improve drainage and lighten their pots without compromising on soil quality, perlite and vermiculite are excellent choices. These naturally occurring materials help to aerate the soil and take up space without adding weight.

Perlite: This volcanic glass material is lightweight and provides excellent drainage while preventing soil compaction. You can mix perlite into your potting soil or use it as a bottom layer to take up space in deeper pots.
Vermiculite: A bit denser than perlite, vermiculite holds moisture well and helps with aeration. It’s best suited for plants that require a lot of moisture, and it can be used similarly to perlite as a space filler.

Tip: Mixing perlite or vermiculite with soil at the base of the pot can improve drainage and create a healthier environment for your plants’ roots.

4. Recycled Garden Materials

Looking for a sustainable way to fill space in your pots? Repurpose items you already have in your garden or home. This not only helps take up space but also reduces waste.

Broken Tiles or Bricks: Old tiles, bricks, or stones can be placed at the bottom of large pots. These materials improve drainage and add stability to taller or heavier pots. Just make sure the pieces are not too large, as this could affect the roots’ ability to grow.
Upside-Down Plastic Pots: Another clever trick is placing smaller plastic pots upside down inside larger ones. This takes up space while also reducing the amount of soil needed. The upside-down pots create an air gap that promotes better drainage.

Tip: When using recycled materials, make sure they won’t leach harmful chemicals into the soil. Avoid painted or treated items unless you’re certain they are safe for plants.

5. Old Compost or Potting Mix

If you have old compost or potting mix that has lost its nutritional value, you can use it as a filler. While it may not be rich in nutrients, it still takes up space and provides structure in the pot. Top it with fresh, nutrient-rich soil for the best planting results.

Tip: When using old compost or potting mix, make sure it’s free from pests or diseases that could affect new plants.

Conclusion

Filling large pots doesn’t have to be a daunting task or result in wasted soil. By using lightweight fillers like polystyrene, eco-friendly options such as wood chips, or recycled materials like old tiles, you can effectively take up space without compromising the health of your plants. With the right fillers, your pots will be lighter, well-drained, and just as aesthetically pleasing.

By experimenting with different materials, you can find the best solution for your garden pots and create a sustainable, cost-effective gardening routine.