Question 1

How much soil do I need for a raised bed?

Accepted Answer

The amount of soil depends on your bed dimensions. Multiply length x width x depth (all in feet) to get cubic feet. For example, a 4x8-foot bed that is 12 inches deep needs 32 cubic feet of soil. Divide by 27 to convert to cubic yards if ordering in bulk. Our calculator above handles all the math for you, including multiple bed shapes and soil mix breakdowns.

Question 2

What soil mix is best for raised beds?

Accepted Answer

The most popular raised bed mix is 60% topsoil and 40% compost, which provides good drainage, nutrients, and structure. Mel's Mix (equal parts compost, peat moss, and vermiculite) is ideal for square foot gardening. For deep beds, a hugelkultur-inspired layered approach with wood on the bottom saves money and improves long-term fertility. Avoid using 100% garden soil, which compacts easily in raised beds.

Question 3

How deep should a raised bed be?

Accepted Answer

Most vegetables grow well in 6 to 12 inches of soil. Shallow-rooted crops like lettuce, herbs, and radishes do fine in 6 inches. Tomatoes, peppers, and root vegetables like carrots prefer 12 inches or more. If your raised bed sits on top of concrete or compacted ground, aim for at least 12 to 18 inches to give roots enough room to grow.

Question 4

Do I need to replace soil in a raised bed every year?

Accepted Answer

No, you do not need to replace all the soil each year. Soil naturally settles and compresses over time, so plan to top off your beds with 1 to 2 inches of fresh compost each spring. Every 3 to 5 years, you may want to amend more heavily by mixing in fresh compost, aged manure, or other organic matter to replenish nutrients and improve soil structure.

Question 5

Can I use regular garden soil in a raised bed?

Accepted Answer

Using straight garden soil in a raised bed is not recommended. Garden soil tends to compact in the confined space of a raised bed, leading to poor drainage and limited root growth. Instead, use a purpose-made raised bed mix or blend topsoil with compost and amendments like perlite or peat moss. If you want to use some garden soil, limit it to about 25% of the total mix and blend it with compost and a drainage amendment.

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