2008 Year in Review

Container Garden Planting-III

Double-potting in your container garden can make changing out seasonal plants a breeze, said a University of Illinois Extension horticulture educator.

"Fresh plants are easily rotated in and tired ones out of a large landscape container holding multiple plants," said Nancy Pollard. "Double-potting makes it possible to sink individual potted plants into the landscape--or remove them--without disturbing the roots."

Landscape planters are also good for combining plants with different requirements. For example, plants that have different soil drainage requirements can be combined in a landscape planter if they are in their own separate pots. On the other hand, if there is not enough light, two sets of plants can be used. As individual plants begin to decline, rotate them back to a higher light area. Replace them with healthy plants.

"It is not always possible to save time and trouble by choosing plants with similar environmental needs or which are well adapted to the conditions available," she said.

Double-potting can also reduce fluctuations of soil temperature. Roots are generally more susceptible to cold damage than are stems or leaves. When over-wintering an otherwise hardy plant, sink the potted plant into the ground. Then mulch over the soil with wood chips, soil or other material to help it survive the winter. The soil temperature underground does not fluctuate like container soil exposed to wind and extremes of temperature.

"Some plants are attractive but spread invasively by underground roots," she said. "These plants invade space that does not belong to them. For example, most people love mints for their fragrance and culinary uses, but they can spread aggressively in the garden.

"To avoid this, sink a large pot into the ground. Then place the invasive mint in a slightly smaller pot liner. This limits the spread of its roots."

The outer container used in double-potting or any container garden use needs to be stable enough to avoid tipping over. It also needs to hold adequate water compared to the size and number of the plants, while withstanding seasonal temperatures and being attractive.

"Shape will determine if a container is stable enough to keep the plant from tipping," she said. "Square pots are the most stable. Traditional pots--sliced-off inverted cones--tip over easily. Pots with straight sides like cylinders are more stable.

"Look for a broader base than height to minimize overturning if that is a concern. Small pots may be 'top-heavy' with plants tipping over more readily. Pots of tall plants may need to be strapped or anchored in place if they become top heavy."

Exposed balconies, rooftops, and decks are especially prone to winds, she added. Consult with a building architect concerning weight limitations when placing pots on balconies or rooftop gardens.

The container's volume affects maintenance. In general, larger plants will need more container room for roots.

Another concern is watering. Succulents that need to dry out between waterings can be placed in a shallow container with little soil. Plants requiring moist, well-drained soil, how4ever, need a larger root ball to guard against drying out between watering.

Given the same number and kinds of plants in the same location and type of container, larger pots need less frequent watering than smaller pots.

"If you plan to go on vacation later in the summer, choose a big pot or a big, self-watering pot," she said. A plant should look like it fits into the container without being squeezed. Never trim the roots to make the plant fit the pot unless you are doing bonsai. Conversely, if the pot is much too big for the plant or the number of plants, the soil will have a tendency to stay wet longer, making root rot more likely.

"Finally, good looks are important," said Pollard. "Be sure to think about the colors and styles of the container compared to its setting."

by  Editor, theCity1.com
March 14, 2008