Laundry tubs are still sold in stores, but I've accumulated four of them as discards -- one came out of my own basement, and three of them were left out on boulevards (the strip between sidewalk and street) in my neighborhood.

These tubs are roughly 20 inches square and 12 inches deep standing on a base and legs with a combined height of 21 inches. That square grows a nice amount of lettuce and green onions -- sufficient for a lot of salads for two people.over late spring and early summer (then the lettuce bolts and turns bitter in the full summer heat). The working height of roughly 28 inches makes planting, tending, and harvesting an easy task. They also keep out cats, who love to use open beds as their litter box.

This can be set up on a balcony or deck as well as on soil. Do be sure to provide somewhere for drained water to go in the event of a heavy rain.

Step 1: Materials and Tools

Materials:

laundry tub
4 bricks to support the tub legs on soil, more bricks for a raised storage area under the tub and a standing area in front of it. These won't be needed if you are setting this up on a deck or balcony. Or set the tub up on a 24 inch patio block.
Bucket to contain drainage (especially important for a deck or balcony setup); alternatively, you can use drainage hose that fits the drain bottom to safely carry off the drainage.
lightweight filler for the bottom of the tub: old planter trays work well for this.
screening to provide support if your planter trays have holes/gaps
water-porous landscape fabric to keep soil from washing down into your filler
container soil or make your own:
- garden soil
- compost and/or soil amendments
- peat moss
(optional) storm door glass panel

Tools:

small shovel or large scoop for handling soil
container or wagon or wheel barrow to mix the soil in
scissor for trimming filler and fabric

Step 2: Obtain Your Tub and Prep It

Your tub should have four legs for utmost stability.

There may be a plumbing fixture attached to the ledge. Remove it. Recycle it if you can.

A short length (4 inches or less) of drain pipe from the drain is okay. Trim if it is longer and you want to have a bucket underneath the tub to collect drainage. Alternatively you can attach an extension to carry off the drainage to a place where it will do no harm (or even provide benefit).

Depending on how the former owners used/abused it, you may have to do some clean up. Some staining is inevitable if it was used for other gardening things, washing excess dyes from clothing, etc. Do be wary of tubs that were chemically abused (in a machine shop, say) and may have some residual contamination in tub sides.

Step 3: Prepping the Tub Site on Soil

Simply set on soil, the laundry tub legs will sink -- often unevenly-- and eventually corrode.

To forestall this, use four bricks, one under each leg, to support the tub. You can also set it on a 24 by 24 inch concrete paver (this will provide support for your drainage bucket and other stored items as well).

I had the bricks on hand, so I used them. I got them from a torn-down chimney that had been sitting around for a while, hence the aged look. I put bricks in the center to support my drainage bucket (I use that water for other potted plants) and extras pot storage. More bricks across the front provide a mud-free space for standing when doing work on the lettuce plot.

Step 4: Setting Up the Tub

Set the tub on bricks or slab with drain hole (and ledge) on the lowest side for effective drainage when there is a heavy rain. That side should be the left, right, or back from the front side facing you.

In a heavy rain, if the excess water is not drained away, it will sit in the tub, making your soil a mass of mud and possibly drowning the roots of your plants.

Drainage is assured by:

making sure the drainage hole is the lowest point in the tub (throw a cup of water in the empty tub once you set it up; if it does not all go down the drain within a minute, you need to reposition it and/or make sure one side is higher than the others.
providing drainage space between the drain hole and soil with lightweight filler
making sure that your soil is "open" enough to drain excess water while having the ability to retain some moisture. A commercial container soil is constructed to do this, but you can also make your own.

Step 5: In-tub Drainage and Soil Retention

I had some planting cells with a flat top and cones underneath that ended in holes. I trimmed two of them to fit in the bottom of the tub.

This filler required some form of screening to span the top holes so that the fabric layer would not sink into them under the weight of the soil mix. I had some sturdy plastic screening that was easily trimmed to fit. Aluminum screening would have served as well. Nylon window screening could serve if stretched taut and stapled to tight-fitting frame.

You can also planting trays that have small holes in them for drainage, trimmed to size and set bottom side up. Lay screen on top if there are gaps than soil could sink into.

I had a scrap length of landscape fabric that was porous enough to allow water to flow through but tight enough to keep soil from seeping through it (eventually compacting and clogging the drain). I cut it so it would fold up the sides of the tub. You would need this whatever filler you used.

Step 6: Mixing the Soil and Filling the Tub

You will need about 1.5 cubic feet of container soil for the tub. A 20 quart bag will be enough.

The soil mix I made up for the tub:

12 quarts good quality garden soil - a loam is best. Substitute in some compost to improve a clayey or sandy soil.
7 quarts peat moss (coir may be substituted - be sure to expand it first) (this is the water retention component of the soil mix)
1 quart per-lite (to keep the soil "open" for drainage and prevent compaction)
1/3 cup dolomitic lime (counters the acidity of the peat moss - omit if using coir)
2 tablespoons green sand (supplies trace minerals)

This will provide a 5" or slightly more layer of soil in the tub. This is ample room for lettuce, green onion, and radish roots.

Step 7: Providing an Early Start for Your Lettuce

The 3 inch space above the soil provides growing space should you decide to start your lettuce early. Mescalin is a lettuce blend perfect for this planter. Take out 2 cups of soil. Mix 1 part seed with 4 parts soil and thinly scatter it over the soil; scatter the rest of the soil on top. You can plant a row of onion sets on one side and a row of radish on the other.

The glass panel from an old storm door or window provides protection, helps trap the sun to warm the soil, and keeps in moisture.

You can start your lettuce while the nights are still frosty, but grass is coming up. If you have daffodils, wait until they start forming flower buds before starting your lettuce seed in the tub under glass. As the days warm, open the glass (propping it up with a wood block or brick) during the warmest part of the day, and closing it as the day begins to cool.

Once your daffodils are in full flower, it will be time to use the glass less and less (threat of freezing nights only).

Enjoy your little salad garden!