Self-Watering & Insulated Planter Boxes

How Self-Watering Containers Work

• Self-watering planters have a reservoir you fill with water. The water wicks into the soil, typically from the bottom, as the soil becomes dry. The planters help reduce over-watering by adding just what the soil needs. They also keep plants alive for a few days if you forget to water -- you just need to remember to refill the water reservoir periodically. The reservoirs vary in size from less than 1 gallon to several gallons, depending on the planter. Most have an overflow hole to ensure outdoor plants don't get flooded with water when it rains or when your sprinkler system waters the area.

Uses for Self-Watering Planters

• Although self-watering planters work indoors or out, some spaces need the convenience of the containers more than others. Small spaces with several planters, for example, can make it hard to reach the planters in the back with your watering can, so self-watering planters can help. They're also handy in hard-to-reach places, such as plants hanging over a balcony or high hanging baskets. Because they water from the bottom up, plants that don't tolerate wet soil might not work as well in self-watering containers as in traditional ones.

Insulated Planters

• Most planters have a certain degree of built-in insulation, depending on the material the planters are made of. Wood tends to insulate better than thin plastic, for example, and concrete insulates better than wood. Planters don't normally have extra layers of insulation, although some plastic planters use foam cores between layers of outer coating. Avoid terra cotta pots in areas that freeze in the winter because moisture soaks into the container and causes it to crack as temperatures drop.

Helping With Insulation

• Help your plants survive the winter or the heat of summer by thinking about insulation before you plant them. Buy containers larger than the plant needs because the extra soil adds an insulating layer. Adding a layer of bubble wrap inside the pot before you pour in the soil also helps. Or, place a small pot inside a large one and fill the gap in between with mulch, making sure all drainage holes function normally. These methods can help you keep plant roots from freezing or getting too hot, but they won't necessarily stop the water in self-watering reservoirs from being affected by cold temperatures. If you can't move the self-watering planters to a protected area, reduce the amount of water in the reservoir so it won't crack if the water freezes and plan to add water to the soil manually about once a week if the reservoir's water stays frozen solid.