Potted plants can create an attractive and mobile garden arrangement for indoor and outdoor spaces. The main consideration with flowers or vegetables grown in containers is that they have adequate drainage. If soil does not drain properly, the excess moisture can cause plant roots to rot or soil can become compacted, robbing roots of necessary oxygen.
Decorative ceramic or terra cotta planters do not always have drainage holes drilled in the bottom of the pots. Use a plastic planting container that has drainage holes as a liner inside of a larger decorative planter to ensure that the soil drains. A container that fits sungly inside of the larger pot will not be visible from the outside, maintaining your decorative needs. Remember to check the water level inside the large pot and pour away any excess when it reaches more than a few inches.
One challenge with planters that have drainage holes is soil washing out through the holes when watering the plant. A coffee filter placed over the hole under the soil can allow water drainage while holding the soil inside the pot. A sheet of cheesecloth can perform the same benefit if coffee filters are unavailable.
Some gardeners choose to line the bottoms of pots that do not have drainage holes with a few inches of gravel to promote good drainage. The University of Illinois Extension website claims that this is a myth and water instead collects in the layer of soil just above the gravel; however, a gravel layer underneath a liner pot can reduce the need to pour out drained water so frequently. Large gravel or stone chips can also act as a barrier to soil washout.
All soils are not created equal when it comes to container gardening. Potting soil, intended for use with potted plants, contains small pieces of a white volcanic rock called perlite. Perlite bits create air pockets in the soil, allowing the soil to stay loose and drain effectively. Perlite can be purchased on its own for addition to your preferred planting mixture.