Check for Drainage Holes
Most plant pots are made with drainage holes so that excess water can drain away (if it can't, plants will rot). If a pot doesn't have holes, you will need to make some. One way of doing this is to drill into the base several times with a masonry bit.
You can either leave the drilled holes as they are, or tap them with a hammer to make one larger drainage hole. Choose clay containers with a thick base, which is less likely to fracture when hit with a hammer.
Stop the Rot
To help water drain freely, place broken terra-cotta pots (crocks), polystyrene chips, or large pebbles in the base of the pot. Alternatively, use a layer of fine mesh with gravel on top. This prevents drainage holes from becoming blocked and soil from being flushed out.
Lighten the Load
Any pot will be heavy when filled with soil, and even heavier after being watered. To reduce weight, fill the bottom third with polystyrene chunks or ceramic balls. Note that this applies only to pots for annuals or plants that don’t have long, extensive roots.
Reusing Old Pots
All pots, including those left in the garden or stacked up in the garage, must be cleaned immediately before use. This applies even if the pots were stored under cover and cleaned months ago, before being put away. Undisturbed pots can be breeding grounds for pests and diseases, larvae, and baby slugs. Don't risk it. Scrub scrupulously with detergent and rinse well. As an extra precaution, you can also soak pots in a mild bleach solution and then rinse well. This is advisable if the containers have previously housed diseased plants.
Clay pots that have not been glazed on the inside are vulnerable to frost damage. This is because they are porous, and when water seeps into them and then expands as it turns to ice, the pot cracks. To prevent this, line pots that you want to sit outside all year with heavy-duty plastic. Always buy more plastic liner than you think you need. Push it well down into the pot, and use a pair of scissors to cut out drainage holes in the bottom. Then place a layer of pebbles or stones in the base, and fill up with potting mix, the weight of which will push the liner down further. Finally, trim away the excess liner flush with the top of the container. Lining terra-cotta pots in this way also prevents salts in the soil and water from leaching through the clay and discoloring your container.
Moving Heavy Containers
It can be a nightmare trying to move large, filled, heavy pots unless you have help, and even then you are in danger of hurting your back and dropping the container. The best solution is to transport your containers on a sturdy wooden dolly, treated with wood preservative. To avoid lifting a filled pot, place it on the dolly before planting, and move to its final destination. The dolly can also double as a pot stand, eliminating the need to lift off the heavy container and allowing water to drain away efficiently.