Garden: Square-foot garden offers large yields in small space

If you don’t have a large space for a vegetable garden, or you are looking to maximize vegetable, herb and flower production in a small space, the square-foot gardening method may be for you.

A square-foot garden is just what the name says − a raised-bed garden laid out in 1-foot squares, where a different vegetable, herb or flowering plant is planted in each square.

The square-foot gardening method is a simple way to create easy-to-manage vegetable gardens that require less time to manage than a typical in-ground garden with plants grown in rows. A square-foot garden is also a great way to engage children in the garden. The 1-foot squares are easy for children to manage and the layout of the garden makes it simpler for children to visualize how the garden should develop.

Square-foot gardens may be particularly useful for new gardeners, as the simple layout makes it easy to calculate how many plants and seeds will be needed.

Getting started with square-foot gardening

Like any other type of vegetable garden, a square-foot garden should be located on relatively flat ground in a location which receives a minimum of six to eight hours of full sun each day.

Locating the garden bed close to the house and a water source may make garden-maintenance chores, such as weeding, watering and harvesting, more convenient and harder to overlook when they are needed. The most common size square-foot garden is 4-foot-by-4-foot, divided into 16 1-foot squares. The bed should be 12 inches deep to accommodate deep-rooted vegetables, such as carrots and tomatoes. The raised bed can be constructed with lumber, cement blocks or other building materials.

Preengineered 4-foot-by-4-foot raised-bed kits are also available at garden centers and online. Treated lumber is safe to use for constructing vegetable-garden beds if the lumber was manufactured after 2004.

Use the correct soil

The raised bed should be filled with lighter raised-bed garden soil. A barrier between the existing inground soil and the added soil is not needed. If you choose to use some of the native soil in your yard for the bed, be sure to amend it with a lighter soil, compost or peat. Work the soil amendment into the native soils at a rate of one-third soil to two-third soil amendment.

Once the bed is filled, build a square-foot grid on top of the garden bed using lattice strips, small PVC pipe or even string attached to the bed. Having the physical grid in place on top of the bed can make it easier to plant in the correct locations in the bed.

Time to plant

A simple formula for planting into the 1-foot squares is to plant one extra-large plant, such as a vine tomato in a one-foot square; four large plants, such as pepper or eggplant in a square; nine medium plants, such as onion or beets in a square; or 16 small plants, such as radishes.

Vining plants, which spread, such as squashes and melons, are more challenging to grow in a square-foot garden. One method for growing these plants in a square-foot garden is to plant them in four squares at the edge of the garden bed and install a trellis at the end of the bed to allow these plants to grow vertically on the trellis.

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If you plant tomatoes in your square-foot garden, be sure to stake them so that they do not crowd out plants growing in nearby squares. You may also want to choose smaller tomato varieties, such as bush or patio varieties. Seeds can be direct-seeded into the squares, and vegetable transplants can be planted into the squares, according to the spacing noted above.

Maintaining the square-foot garden

While your square-foot garden may take a little less work than in-ground vegetable plantings in rows, be sure to provide regular weeding and watering, as well as fertilization when needed. You will find that fewer weeds will germinate in the more densely planted square-foot garden, and weeds, which do germinate will be easier to remove in the lighter-amended soil in the bed.

You will also find harvesting simpler in a square-foot bed, as long as the bed is not larger than 4-feet wide. Beds larger than 4-feet wide make it difficult to manage plants without walking on the soil in the raised bed. Remember to harvest all vegetables when they are young, tender and at their flavor peak.

Lighter soils in a square-foot garden with a more intensive spacing may dry out more quickly than inground soils, so be sure to monitor soil moisture when rainfall is not adequate. Anyone can be a successful gardener using the square-foot gardening method. Once you are comfortable managing a 4-foot-by-4-foot square-foot garden, you can build additional beds if you require additional planting space.

Mike Hogan is Extension Educator, Agriculture and Natural Resources and associate professor with Ohio State University Extension.

hogan.1@osu.edu