Get the dirt on proper container gardening

With spring just around the corner, there's a cheerful impulse to freshen up the deck and patio containers with bright new blooms.

To help your container plants get a good start, let's go over a few myths and tips on proper care:

Filling pots

Myth: Fill the bottom of the pot with gravel, small rocks, marbles, chunks of broken crockery and/or charcoal to "help the plant drain better."

Truth: It's not what you may expect — plants grow best if the entire pot is filled with soil without the encumbrances of gravel or crockery.

Water doesn't easily flow from a fine-textured medium through a rougher texture; what's created is called a "perched water table," and you can imagine it as water collecting, sitting below the roots and keeping soil too wet.

Proper care: Fill the pot with soil. If you worry about soil seeping out of the drain holes, cut a piece of a paper coffee filter, window screen or mesh drywall tape and lay it over the hole.

Sizes of pots

Myth: Smaller pots make care easier.

Truth: No, all that's easier about small pots is toting them around.

Smaller pots require watering more often, and they can confine plant roots, which results in less plant growth as months progress.

A few herbs like thyme and ornamentals like geraniums do grow well when "root-bound" (when roots have filled up the pot and touch the outer rim). But these plants are rare.

Proper care: Containers at least 9 inches tall and 6 inches across are a good minimum size. I like to settle annual flowers into pots at least 12 inches tall and 16 inches across.

Types of containers

Myth: Plants will grow in any container.

Truth: Not quite. You've seen those magazine articles with the priceless Limoges chamber pot full of blooming tulips? That's illusion. Florists grew the tulips separately and slid them into the Limoges long enough for a photograph.

Proper care: You can repeat the trick if you have a prized tureen. Grow the plants in another container that has proper drainage, and slip the plants into the tureen only for brief, celebratory occasions. When the event is over, pop the plants back out into their growing containers.

Saucers

Myth: Saucers underneath containers help plants grow.

Truth: Saucers are better at protecting what's under the container than what's in it. Drainage can fail, especially in rainy weather, when the plant sits in its own juices. Containers sold with attached saucers truly annoy me; I always want to yank them off and stomp on them.

Proper care: If the plant is on a carpet or deck that needs protection, saucers can be OK if you dump the water out after rain or irrigation. On decks I like "plant feet" that raise the pot about an inch, allowing it to drain. The "feet" often come in the shape of claws, a funny touch making them resemble antique furniture, or in the shape of animals. You also could raise outdoor plants on bricks or wood blocks.

Potting soil

Myth: Potting soil wears out and needs replacing annually.

Truth: Nope. Carry on with it.

Proper care: If needed, you can revive the soil. If plants in the pots were healthy, dump out the soil, shaking out roots and plant debris. Next, fluff the soil to add oxygen. Then improve the soil by mixing in pumice or perlite. (The amount of pumice or perlite you add to the container should be about one-fourth the amount of soil.) Presto! Revived soil.

I have some that probably predates the Carter administration.

Garden expert Mary Robson is retired area horticulture agent for Washington State University/King County Cooperative Extension. Her e-mail is marysophia@olympus.net