Small Space Gardening

Lesson 2: Designing Your Square Foot Garden

Prepare Your Soil

Soil was briefly mentioned in the first part of this lesson. Let’s delve deeper into the subject of garden soil since this determines how well any plant grows. In fact, I view soil preparation as the most important item in creating any style garden.

Soil is made up of various particles. The basic components, listed from smallest to largest are: clay, organic matter, and sand. Some soil has rocks of various sizes mixed in it too. Soil that has little or no organic matter is often referred to as “dirt” and tends to be a light color. Rich topsoil, with plenty of organic matter, is normally dark in color.

Soil can be classified as loam (equal parts of clay, sand and organic matter), sandy loam (more sand than clay), or clay-loam (more clay than sand). Drainage is controlled by the mixture of these components. If the soil is primarily clay, it will hold copious amounts of water. Water drains quickly through sand. Most vegetable gardeners prefer loam. If you specialize in bog plants, you may need more clay in your soil so it stays wet longer. Alternatively, if you grow plants from the alpine regions, you want a mixture of sand, clay, organic matter, and gravel so it drains rapidly. Roots have a harder time growing into clay than they do into loam or sandy loams. Pure clay is almost impermeable whether it is wet or dry. Pure sand holds almost no water. The organic matter in your soil acts like little sponges to soak up water after a rainstorm. Therefore, the amount of organic matter in your soil will determine the water holding capacity of that soil.

When I discuss gardening with any audience, I try to make it clear that there are plants suitable for growing in every type of soil, from the leanest (with little organic matter) to pure water! However, gardeners generally prefer to use soil that has plenty of organic matter mixed in it. This is particularly true if you want to grow your own food crops.

Activity: Determine your soil type. What type of soil do you have? If you can’t decide from the descriptions given above, try this activity. I’ve used it with many adults and young people new to gardening. Pick up a handful of your soil. Try squeezing it into a ball. Compare your result with this chart:
Clay: Soil stays in a ball shape and feels slightly sticky.
Sand: Soil completely disintegrates; refuses to hold any shape.
Loam: Soil breaks apart in small clumps.

Help! I don’t have Loam Soil

Gardeners often find they need to improve their soil. Few of us are blessed with naturally occurring loam soil. What can you do to improve your soil? The basic answer, for any type of soil, is to add organic matter to the soil. This improves the soil texture and the water holding capacity. There are many things you can add to your soil. Here are some examples:

Compost. Most experienced gardeners have compost piles. Compost is simply organic matter than has been decomposed by bacteria into a crumbly, dark colored substance. This substance contains the nutrients that were locked up in the vegetable and fruit peelings, coffee grounds, and other plant derived materials layered into the original compost pile. Compost is considered the best organic material to add to improve soil texture, water holding capacity, and fertility. Since this isn’t a course on composting, please read pages 53-56 of your textbook for more detailed information on composting.

Chopped Leaves. Bags of leaves are freely available every fall. If you don’t have enough in your own yard, just visit your neighbors. They’ll be more than happy to give you theirs. Scatter the leaves on a flat surface (yard, driveway) and run your lawnmower over them several times before adding them to your soil.

Mushroom Compost. This material is often available for free or a very low price from any company that provides mushrooms to the grocery industry. Check around your area and see if anyone locally doing this.

Composted Manure. Never make the mistake of using fresh manure on any garden. It can have disease organisms and weed seeds in it unless it has been processed first in a “hot” compost pile. You can often buy plastic bags of composted manure at your garden center.

Chopped straw. If you want to use this, be sure it is weed seed free or you are just liberally applying a layer of weed seeds to your garden. I’ve seen too many homeowners create a lawn of “weeds” by applying straw over a newly seeded lawn, much to their dismay.

Grass Clippings. Grass is an excellent soil improver, providing it isn’t full of weed seeds, or herbicide chemicals.

Seaweed. Gardeners living near the ocean often find seaweed being sold as a soil improver.

Peat Moss. Spaghum peat moss is highly recommended as a soil improver. The main limitation is its cost. Don’t make the mistake of buying the sedge peat, sometimes called “Michigan peat” because it breaks down within a few weeks and has little lasting value.

Chopped bark. Chopped pine bark is a “softwood” mulch that easily breaks down over the course of a year.

There are other organic items that could be used to improve your soil. I’ve identified those that are most available. Feel free to explore your area to see what else you can find as a by-product of food production.

Bartholomew’s Soil Mixture

Bartholomew's book contains a recipe for a perfect soil mixture. If you've borrowed or purchased the book, it is on page 65. The results will have the right texture, water holding capacity, and pH immediately.

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