Your First Raised Bed

One bed, four feet by eight, ten inches deep. It is the size almost every first raised bed should be, and the reasons are all practical rather than traditional.

Four feet wide because you can reach the middle from either side without stepping in — compacted soil is the thing that quietly ruins a bed. Eight feet long because lumber comes that way and you will not waste a cut. Ten inches deep because that is enough root room for nearly everything except carrots and parsnips.

Before you build: where

This decision matters more than anything else on the page, and it is the one that cannot be undone once the bed is full.

• Six hours of direct summer sun, minimum. Eight is better. Watch the actual spot across a day before committing — almost everyone overestimates how much sun a yard gets, and shade in July is not shade in April.
• Within reach of a hose. A bed you have to carry water to is a bed that gets watered less. This is not a character flaw, it is just true.
• Reasonably level. A slope drains to one end and drowns that end.
• Not against a fence unless you can still reach it. Access from both long sides is the whole point of four feet.

What to buy

Item	How much	Notes
2×10 or 2×12 boards	Two 8′ and two 4′	Cedar lasts longest untreated. Untreated fir is cheapest and gives you five or six years.
3″ exterior screws	A small box	Deck screws. Pre-drill the ends of the boards or they split.
Corner posts (optional)	Four short 2×4 offcuts	Screwed inside each corner, they stop the long sides bowing outward once the soil is in.
Cardboard	Enough to cover the footprint	Plain corrugated, tape removed. This is your weed barrier.
Soil mix	About 1 cubic yard	See below — this is the expensive part and the part worth getting right.

1. Build the frame

Screw the two 4′ boards between the ends of the 8′ boards, so the outside dimension is 4′ × 8′. Pre-drill; construction lumber splits at the end grain almost every time otherwise. Add the corner posts inside if you are using them.

Set it in place and check it is level. Now, while it is empty, is the only easy time to fix that.

2. Kill what is underneath

Lay cardboard across the whole footprint, overlapping the seams by several inches, and wet it down. It smothers the grass, breaks down over a season, and lets worms through. Do not use landscape fabric — it lasts long enough to become a problem later and stops the bed connecting to the ground beneath it.

3. Fill it

A 4′ × 8′ bed at 10″ deep takes about 26.7 cubic feet, which is very close to one cubic yard. Work it out yourself with the bed soil calculator, which also splits it by component and tells you what it is in bags.

That volume is the moment to know one thing: at roughly half a cubic yard, bulk soil delivered by the yard becomes cheaper than bags, usually by a lot. One bed is already past that line. Eighteen bags is also a car you have to unload.

A workable mix for a first bed is roughly half topsoil, thirty percent compost, twenty percent something for aeration. Do not fill it with bagged “potting mix” — that is designed for containers, it is expensive at this volume, and it dries out badly in a bed this size.

Fill to about an inch below the rim. It settles.

4. Plant something forgiving

First season, choose plants that tell you quickly whether things are working:

• Bush beans — direct sown, up in a week, productive, nearly impossible to kill.
• Leaf lettuce — fast, cut-and-come-again, and it tolerates the cold either end of the season.
• Radish — ready in a month. Mostly worth growing because it proves the bed works.
• Zucchini — one plant. Truly, one. It will take a quarter of the bed and feed a street.
• Determinate tomato — two plants, caged, if your season is long enough.

The spacing calculator will tell you how many of each fit, and the seed starting schedule will tell you when to sow, counted back from your own last frost date. That date is local and worth getting from your state extension service rather than guessing.

5. Water properly

Vegetables want roughly an inch of water a week, rain included. Over a 4′ × 8′ bed that is about 20 gallons.

Deliver it in one or two long soaks rather than a daily sprinkle. Frequent shallow watering trains roots to stay near the surface, where they dry out fastest. Push a finger in to the second knuckle: damp means wait.

What goes wrong the first year

• Not enough sun. The most common cause of a disappointing first bed, and the only one you cannot fix later. Six hours.
• Too many plants. See above. One zucchini.
• The soil settled two inches. Normal. Top up with compost each spring; that is most of what maintenance means.
• Watering little and often. Fewer, deeper soaks.
• Everything planted at once in May. Lettuce and radish want the cool ends of the season; beans and squash want the middle. The schedule calculator spreads them out.

One bed is genuinely enough for a first year. It is enough to learn what your light does, how fast your soil drains, and what you actually eat. Build the second one next spring, once you know those three things.