Guide to Filling Large Planters: Best Practices, Drainage, and Maintenance

1. Ensure Proper Drainage

Good drainage is key to keeping your plants healthy and preventing root rot. Large planters, especially outdoors, need good drainage to keep water from sitting in the soil.

• Drainage Holes: Make sure your planter has enough drainage holes. If not, consider drilling extra holes at the bottom. Without enough drainage, water can accumulate, causing root rot and potentially killing the plant. If you are unsure about the number of holes, it is better to have more rather than too few.
• Layering: Add a layer of gravel, broken pottery, or pebbles at the bottom to help water drain. A 2-4 inch layer works well for large planters. This layer helps prevent the soil from becoming waterlogged, which is especially important for plants that don't like their roots to stay wet.
• Geotextile Fabric: Place a piece of fabric over the drainage layer to keep soil from mixing with the gravel. This will help keep the drainage layer working properly. It also makes it easier to repot or refresh the soil later since the drainage materials will stay separate from the soil.

For more detailed information on preparing your planters, check out our article on Planter Preparation and Drainage.

2. Choosing the Right Soil

The type of soil you use is very important for your plant's health. Using the wrong soil can affect drainage, root growth, and overall health.

• Potting Mix vs. Garden Soil: Always use a high-quality potting mix instead of garden soil. Potting mix is lighter, which allows better airflow and drainage. Garden soil is often too dense and can hold too much water, leading to poor plant growth or root rot.
  • Light Potting Soil Mix vs. Organic Compound Mix:
    • Light Potting Soil Mix: Typically weighs between 20 to 40 pounds per cubic foot when dry, and 60 to 80 pounds when wet. It is made from materials like peat moss, perlite, vermiculite, and compost. This mix provides good aeration and drainage, making it ideal for container plantings, especially in fiberglass planters. The lighter weight also helps prevent stress on the container.
    • Organic Compound Soil Mix: Weighs around 30 to 50 pounds per cubic foot when dry, and 80 to 100 pounds when wet. This mix includes compost, organic fertilizers, and other organic matter, which allows it to retain more moisture. However, the increased water retention also makes it much heavier when wet, potentially causing stress on the planter. This type is better for moisture-loving plants but may not be ideal for use in fiberglass planters due to the risk of structural issues if drainage is not sufficient.
• Additives: Depending on your plant, you can add perlite or vermiculite to improve drainage. For plants that need more moisture, add some peat moss. Perlite helps to keep the soil light, while vermiculite retains moisture, which can be very helpful in maintaining a balanced soil environment.
• Organic Matter: Mix in compost to provide nutrients. Compost also helps retain moisture and keeps the plant healthy longer. Adding organic matter improves the soil structure and adds beneficial microorganisms that help plants grow stronger and resist diseases.

3. Proper Placement Before and After Filling

Large planters can get very heavy when filled, so decide where they will go before filling them.

• Pre-Filling Placement: Move the planter to where you want it before filling it. This way, you avoid injuries from moving a heavy planter. Large planters can weigh hundreds of pounds when filled, so planning ahead can save time and effort.
• Consider Sunlight: If your planter is going outside, think about how much sunlight the area gets. Choose a spot that matches what your plants need. Full-sun plants need at least 6 hours of direct sunlight, while shade plants do better with indirect light.
• Indoor Considerations: For indoor planters, think about foot traffic and how close they are to windows. Large planters can make great focal points in places like entryways or living rooms. Be careful not to block windows or doorways, and ensure the planter is in a spot where it won’t be easily bumped into.

Explore our range of rectangular planters and round planters to find the perfect fit for your space.

4. Transplanting Plants into Large Planters

Transplanting helps your plants establish strong roots in a new planter.

• Root Preparation: Before putting the plant in the planter, gently loosen the root ball. This helps the roots spread out and grow better. For root-bound plants, use your fingers or a small tool to untangle the roots so they don’t stay in the shape of the old pot.
• Positioning: Put the plant in the center of the planter and make sure it's at the right depth. The top of the root ball should be about 1-2 inches below the rim of the planter to prevent soil from washing out. Planting too deep can cause the stem to rot, while planting too shallow may expose the roots.
• Backfill Carefully: Fill the planter with your soil mix, pressing gently around the root ball. Don’t pack the soil too tightly as it can restrict root growth. Lightly pressing the soil ensures the plant stays upright while allowing room for the roots to grow.

5. Maintenance Tips for Large Planters

Large planters need regular maintenance to keep plants healthy. Here are some tips to keep them in good condition:

• Watering: Water until excess water drains from the bottom. Check the soil regularly—large planters retain water longer, but they can also dry out fast on hot days. To avoid overwatering, let the top inch of soil dry out before watering again. Using a moisture meter can help determine when it’s time to water.
• Fertilizing: Use a slow-release fertilizer to provide steady nutrients. You can also add liquid fertilizer during the growing season for an extra boost. Be careful not to over-fertilize, as too much can burn the roots and damage the plant.
• Pruning and Grooming: Remove any dead or yellowing leaves to keep your plants healthy. Prune plants to encourage growth and maintain their shape. Regular grooming not only improves the plant’s appearance but also helps prevent pests and diseases.
• Inspect for Pests: Large planters can attract pests, especially outdoors. Regularly check for pests like aphids or spider mites and act quickly if needed. You can use insecticidal soap or neem oil to manage common pests. Early detection is key to preventing infestations.
• Cleaning the Planter: Use a little bit of soap and water to clean any smudges on your planter. If the finish is gloss, you can also apply some turtle wax (since this is automotive-grade paint, it can be waxed like a car) to restore shine. Regular cleaning will ensure the health of your plant and the longevity of your planter.

For more tips on using plants for your office decor, read our article on The Benefits of Plants in the Office.

6. Best Practices for Filling Large Planters

• Lighten the Load: Large planters can be very heavy when filled with soil. To make them lighter, fill the bottom third with lightweight materials like empty plastic bottles, foam blocks, or pool noodles. Cover these with fabric before adding soil. This not only makes the planter easier to move but also reduces the amount of soil needed.
• Mulch for Moisture: Adding a layer of mulch on top of the soil helps retain moisture and reduces how often you need to water, which is especially useful for outdoor planters. Mulch also helps prevent weeds from growing and keeps the soil temperature more consistent.
• Choose the Right Plants: Think about the planter size and environment. Larger planters work well for trees, shrubs, or multiple plant combinations. Mixing different plant types can create a visually interesting display. Check out our outdoor planter collection for ideas.
• Seasonal Changes: If you’re using your large planters outdoors, consider changing the plants with the seasons. In spring, you can plant flowers, while in winter, consider evergreens or decorative branches. This keeps your planters looking fresh year-round.
• Water Reservoirs: For planters that tend to dry out quickly, consider using a water reservoir or self-watering system. These systems help keep the soil consistently moist and reduce the need for frequent watering, making them perfect for busy plant owners.

Learn more about maximizing your outdoor space with our guide on Reimagining Your Home: Tall Planters Outdoor Design Magic.

Conclusion

Filling a large planter the right way makes sure your plants have the best conditions to grow. From drainage and soil to placement and maintenance, each step is important. By following these guidelines, you can create beautiful, healthy plant displays that will thrive for years. Large planters are not only functional but also enhance the look of your indoor and outdoor spaces.

For more planter options and inspiration, explore our planter collections to find the perfect planter for your next project.