Square Foot Gardening: Ten Gardening Basics
Always think in squares: layout your garden in 4 foot by 4 foot planting areas with wide walkways between them.
Build garden box frames no wider than 4 feet and 6 to 8 inches deep. The length is not as important, but a recommended size for your first time is one 4’ x 4’ garden box. You can of course make it shorter than 4 feet. A 2’ x 2’ foot works great on patios and a 3’ x 3’ box is the ideal size for kids.
Frames can be made from almost any material except treated wood, which has toxic chemicals that might leach into the soil. 1” x 6” or 2” x 6” lumber is ideal and comes in 8-foot lengths. Most lumber yards will cut it in half at little or no cost. Exact dimensions are not critical. Deck screws work best to fasten the boards together. Rotate or alternate the corners to end up with a square inside.
If you plan to have more than one garden box, separate them by 2 or 3 feet to form walkways.
4. Square Foot Gardening Soil
Fill frame with SFG Soil: a mixture of 1/3 blended compost, 1/3 peat moss, and 1/3 coarse vermiculite. No existing dirt is needed or desired in your SFG garden. Peat moss and vermiculite help hold moisture and keep the soil loose. A blended compost made from at least 5 different ingredients provides all the nutrients the plants require. No chemical fertilizers are needed, so everything you grow is organic and nutritious. Some stores might sell mulch or humus and other ground covers and call it compost. Most commercial compost is made from one or two ingredients, so don’t buy all of one kind. Make sure to purchase a variety of ingredients until you have enough for your garden. The best compost you could ever use is homemade because then you know what goes in it.
If time is an issue, we sell pre-mixed Square Foot Gardening Soil at participating locations of Home Depot, Lowes and independent gardening centers and nurseries stores around the country. Click here to find the closest location to you.
On top of each frame place a permanent grid that divides the box into one foot by one foot squares. The grid is the unique feature that makes the whole system work so well. To show you why the grid is so important, do this little demonstration:
Look at your 4 foot by 4 foot box with the grid on and imagine up to 16 different crops. What you see before you is a neat, attractive, well organized garden that will be easy to manage. Now remove the grid. Could you organize and manage this space without dividing it up into squares? Besides without the grid you will be tempted to plant in rows, which is a poor use of space.
Grids can be made from nearly any material: wood, plastic strips, old venetian blinds, etc. Use screws or rivets to attach them where they cross. On a 4 foot by 4 foot frame the grid divides the frame into 16 easy-to-manage spaces, for up to 16 different crops. Leave the grid in place all season. The grid can be cut long enough to fit across the top of the box or cut shorter to lay on the soil inside the box.
Since you NEVER want to walk on or depress the growing soil, don’t make the frames any wider than 4 feet (2 feet, if only one side is accessible). Any wider makes it too difficult to reach in to tend the plants.
Depending on the mature size of the plant, you can grow 1, 4, 9, or 16 equally spaced plants in each square foot. If the seed packet recommends the plant spacing to be 12 inches apart, plant one plant per square foot in the center. If the recommendation is 6 inch spacing; divide the square into 4 smaller squares and plant 4 plants per square foot. If it recommends 4 inch spacing; divide it into 9 parts and plant 9 per square foot. For 3 inch spacing; plant 16 plants per square foot.
Make a shallow hole with your finger and drop 2 to 3 seeds into the hole. Cover the hole backup but do not pack the soil down. Thinning extra seedlings is all but eliminated and seeds are not wasted. Extra seeds can be stored cool and dry in your refrigerator.
Make sure to avoid over-planting and only plant as much as you will use for each crop. A 4 foot by 4 foot box will grow more than a conventional row garden that is 8 foot by 10 foot.
Water only as much as each plant needs. Water often, especially at first, and on very hot, dry days. If possible it is best to water by hand with a cup from a sun-warmed bucket of water. Watering by hand will use less water and the warm water helps the soil warm up in early and late season.
Harvest continually throughout the plant’s harvest period. When a crop in one square is finished, remove the old plant, add some new compost, and plant a new different crop in that square.