Raised Bed Planner
Enter your raised bed dimensions to get a square foot grid and soil volume.
Planting Grid (1 square = 1 sq ft)
Plants Per Square Foot
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
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This planner calculates the number of one-square-foot planting squares in your raised bed and the soil volume needed to fill it. A visual grid shows your bed layout. Here is how to use it:
- Enter your bed dimensions. Length and width are in whole feet for best results with the square foot gardening method. Common sizes are 4x4, 4x8, and 4x12. Beds wider than 4 feet are hard to reach across from the sides.
- Set your soil depth. Twelve inches is the standard for most vegetables. Shallow-rooted crops like lettuce work fine at 6-8 inches. Root vegetables like carrots need 12-18 inches. The deeper the bed, the more soil and the better the drainage.
- Read the grid. Each square in the grid represents one square foot. Use the crop reference table to decide how many plants to place in each square.
- Calculate your soil. Use the bag count to shop for soil. Most raised bed mixes come in 1 to 2 cubic foot bags. Add 10% extra to ensure you fill the bed completely.
About the Raised Bed Planner
Square foot gardening was popularized by Mel Bartholomew in the 1980s. The core idea is to divide your raised bed into a grid of one-square-foot sections and plant each section according to the size of the crop. Larger plants like tomatoes get one square each. Smaller plants like carrots can fit 16 per square. This intensive approach maximizes yield in a small space and makes it easy to plan crop rotations.
The soil calculation uses the same formula as our standalone Soil Calculator: length times width times depth (converted to feet) gives cubic feet. Divide by 27 for cubic yards. The bag count uses a 1.5 cubic foot bag as the standard, which covers many popular raised bed soil products.
Frequently Asked Questions
What size raised bed is best for beginners?
A 4x8 foot raised bed is the most popular size for good reason. You can reach into the center from either side without stepping on the soil, which keeps the growing medium loose and uncompacted. The 32 square feet gives enough room to grow a meaningful variety of vegetables: a couple of tomato plants, a block of lettuce, some peppers, and a few herb squares. Start with one 4x8 bed before investing in a larger system.
What is the best soil mix for a raised bed?
Mel's Mix, the original square foot gardening soil recipe, calls for equal parts compost, peat moss, and coarse vermiculite by volume. The compost provides nutrients and microbial life, peat moss retains moisture and creates a light texture, and vermiculite improves drainage and aeration. Many gardeners substitute coconut coir for peat moss due to sustainability concerns. A simpler starting point is a good commercial raised bed mix blended with 20-30% extra compost.
How many tomatoes can I grow in a 4x4 raised bed?
In a 4x4 raised bed using square foot gardening rules, you can technically plant 1 indeterminate tomato per square. Most experienced gardeners limit themselves to 2-4 tomato plants in a 4x4 bed and use the remaining squares for companion plants like basil, marigolds, and shorter crops. Indeterminate tomatoes grow very large and benefit from vertical support. Four tomato plants in a 4x4 bed is manageable with cages or a trellis system.
Do I need to line the bottom of my raised bed?
It depends on where the bed sits. If placed on grass or soil, lining with cardboard or newspaper suppresses weeds while the bed is getting established, and decomposes over time. Hardware cloth (wire mesh) on the bottom deters burrowing pests like moles and voles. If the bed sits on concrete or a deck, you do not need a liner for weeds, but drainage holes or gaps are essential. Avoid landscape fabric as a bottom liner because it restricts root penetration into native soil and restricts drainage over time.