In spring, it seemed the obvious thing to do: Expand a few feet over here, add on a few feet over there. Plow and till and enlarge all over. But now it’s time to clean up all that extra garden space. What were we thinking?

With the vast beauty of the garden long killed by frost, these end-of-the-growing-season-days mark, for some gardeners, the onset of the most daunting gardening tasks: cleaning up the garden. Days of pulling, hauling and piling into the compost pile.

Then the eyes settle on what now seems to be the most sensible creation on God’s green earth: the tidy container garden. Deliciously compact and yielding high-intensity rewards, this modestly proportioned horticultural indulgence is a sweet sight. At this spectacle, the intimidating end-of-season work for those with hundreds of square feet of garden beds is juxtaposed with something of reasonable scope: just a bit of tidying up here and there.

This is something to impress upon the horticultural appetite that prevails every spring: Think autumn, not spring. At a time of year when work in the vast garden yields but little reward, simply emptying, cleaning and storing containers from the patio garden really brings to light another sensible side of what is, for many, the only practical way to garden.

This time of year offers the container gardener – as well as the “in-ground” gardener – an opportunity to analyze the successes of the season. Foremost, seasonal cleanup gives one something of an inside look at the life of a containerized plant.

By nature, container gardening provides limited space for roots to thrive. Thus, the gardener must be conscientious about supplying for a plant the best environmental conditions possible. Second to selecting an appropriately sized container for a plant or group of plants, selecting a proper potting mix for a container garden is key. In fall, removing potted plants from their summer home tells a story about what they have enjoyed – or endured – over the summer months.

Compacted or waterlogged media in a pot are a sure signal that the potting materials used for the garden allowed an inadequate balance of structure for water drainage and water holding. Quality media allow water to be easily absorbed, penetrating without difficulty to the roots, while still allowing excess moisture to flow through the profile of the container. Also, satisfactory media must be heavy enough to support the plant and offer ballast against wind during the growing season.

If, during seasonal cleanup, one notices waterlogged container mix, make note to improve the media for the next season. A perpetually waterlogged root environment in any soil – containerized or in-ground – may lead to infection of plant roots by moisture-loving diseases, and fungal organisms in particular.

How would the gardener manipulate an ineffective growing material for the container garden? By changing the proportion of ingredients in the media, various effects may be achieved.

Commercial or quality homemade media are typically composed of a variety of components. Many “soilless” mixes include peat moss, ground bark, vermiculite and perlite. Each component is placed in the mix for a specific purpose.

Peat moss has an acidic pH and holds water and nutrients very well. Ground bark, a by-product of the timber industry, is less expensive than peat moss, and so provides an economically attractive bulking ingredient. Compared to peat moss, bark does not hold water or nutrients very well, but it may provide better aeration and drainage.

Vermiculite is derived from a mica-like mineral. It is heated at high temperatures to form silvery flakes 20 times larger than their original thickness. While vermiculite provides some nutrients, its main function is to hold water.

Perlite is volcanic material, crushed and heated to form porous white particles. Its main purpose is to provide aeration.

When removing plants at the end of the growing season, determine if your mix provided an environment that was too dry or too wet for your plants. Simultaneously, determine which elements of the mix, as noted above, should be changed in order to remedy the ineffective media.

Next week: sanitizing containers and overwintering potted plants.

Diana George Chapin is the NEWS garden columnist. Send horticulture questions to Gardening Questions, 512 North Ridge Road, Montville 04941 or e-mail dianagc@midcoast.com. Selected questions will be answered in future columns. Include name, address and telephone number.