Proper drainage is crucial for healthy plants in urban planter boxes. If your plastic planter lacks adequate drainage, adding extra holes is a simple DIY solution. Here's a safe, step-by-step method to drill additional drainage holes.
You will need a power drill (cordless is ideal for control), drill bits suitable for plastic (such as twist bits or spade bits between 1/4 to 1/2 inch), safety glasses, a permanent marker, and a scrap piece of wood.
First, empty the planter box completely of all soil and plants. Turn the planter upside down. Use the marker to clearly indicate where you want the new holes. For most planters, adding 3 to 5 extra holes, spaced evenly across the bottom, is sufficient. Place your scrap wood inside the upside-down planter where you will be drilling. This provides a stable surface for the drill bit to exit into, preventing the plastic from cracking or splintering.
Select your drill bit and secure it in the drill. Put on your safety glasses. Start drilling at a slow to medium speed. Do not apply excessive pressure; let the drill bit do the work. Applying too much force can cause the plastic to crack. Drill straight down through the planter bottom and into the scrap wood. Once the hole is complete, pull the drill out smoothly.
After drilling all the new holes, clean the planter to remove any plastic shavings. You can now add a layer of gravel or pebbles at the bottom (optional, as debated by gardeners) and refill with fresh potting soil and your plants.
Key tips for success: Always use a sharp drill bit for a clean cut. Drilling from the inside of the planter outwards can sometimes create a cleaner hole, but using a backing board is essential. For larger planters, consider more holes to ensure water doesn't pool at the bottom. This simple upgrade will significantly improve soil aeration and drainage, helping to prevent root rot and promote a healthier urban garden.