You can build a functional garden planter from wood, concrete, or metal using basic tools and materials you may already have

A homemade planter costs less than a store-bought one and takes a weekend afternoon to build. The simplest version—a wooden box—requires only a saw, a drill, four boards, and screws. You choose the size, depth, and wood type, which means you can match your garden layout exactly instead of fitting your plants to whatever dimensions a retailer decided on.

The trade-off is that you do the work yourself. You'll need to measure twice, cut once, and handle fastening the pieces together. If you've never used a power drill or circular saw, this is a good first project—the stakes are low, the steps are straightforward, and mistakes are forgiving. A planter that's slightly crooked still holds soil and grows vegetables.

Key Takeaways

  • A wooden planter box requires only a saw, drill, four boards, and exterior-grade screws—no special skills needed.
  • Cedar and redwood resist rot longer than pine, but pine costs less and works fine if you line the interior or replace it in five to seven years.
  • Concrete planters are heavier and more durable but require a mold, concrete mix, and curing time of at least a week.
  • Metal stock tanks and galvanized troughs work as planters with minimal modification—just drill drainage holes in the bottom.
  • Every planter needs drainage holes so water doesn't pool and kill roots.

Building a Basic Wooden Planter Box

Start with four boards cut to length. For a 4-by-8-foot planter 12 inches deep, you need two boards 8 feet long and two boards 4 feet long, all cut from 2-by-12 lumber (which is actually 1.5 inches thick and 11.25 inches tall—standard lumber sizing). A home center will cut these for you if you ask, or you can cut them yourself with a circular saw.

Lay the boards flat on level ground in a rectangle. Drill pilot holes (small starter holes) through the ends of the shorter boards into the ends of the longer boards—two holes per corner, staggered vertically so they don't split the wood. Drive 3-inch exterior-grade screws through these holes. Exterior-grade means they won't rust. Tighten them snug but not so hard you strip the wood.

Flip the box over and drill four drainage holes in the bottom, one near each corner. These holes prevent water from pooling and rotting the roots. If you're placing the planter on soil, you can skip this step—water will drain naturally—but if it sits on concrete or a deck, drainage holes are essential.

Choosing Wood That Lasts

Pine is the cheapest option and works fine for a planter that will last five to seven years. Cedar and redwood cost more but naturally resist rot and can last 10 to 15 years. Pressure-treated lumber is durable but historically contained chemicals that leached into soil; modern pressure-treated wood is safer, but many gardeners avoid it for vegetables out of caution.

If you use pine and want it to last longer, line the interior with landscape fabric or a rubber pond liner before filling it with soil. This barrier keeps wet soil off the wood and extends its life by several years. Staple the liner to the inside walls, leaving a few inches of slack so it doesn't tear when you add soil weight.

Avoid plywood and particle board—they absorb water and fall apart quickly. Solid boards, even cheap pine, hold up much better.

Making a Concrete Planter

Concrete planters are heavy, durable, and look finished, but they require a mold and patience. You'll need two boxes—one larger (the outer mold) and one smaller (the inner mold)—plus concrete mix, water, and a way to remove the inner box after the concrete sets.

The simplest approach: use two plastic storage bins, one inside the other, with spacers (wood blocks or plastic shims) holding the inner bin centered. Mix concrete according to the bag instructions, pour it into the gap between the bins, and smooth the top. Let it cure for at least seven days before removing the molds. The longer it cures, the stronger it becomes.

Drill drainage holes in the bottom once the concrete is fully cured. A concrete bit in a power drill works, but it's slow and dusty—wear a dust mask. Alternatively, you can drill holes before pouring by placing a dowel or PVC pipe through the center of the inner mold, but this requires more planning.

Repurposing Metal Tanks and Troughs

Stock tanks (large metal containers used for livestock water) and galvanized troughs are ready-made planters that need almost no modification. They're durable, affordable if you find used ones, and deep enough for most vegetables. The main drawback is weight—a full tank is heavy and difficult to move.

Drill four to six drainage holes in the bottom using a metal bit. If the tank has a drain plug, you can remove it instead. Add a layer of gravel or broken pottery at the bottom to keep soil from clogging the holes, then fill with soil and plant.

These containers rust over time, especially if you're in a humid climate, but the rust is cosmetic and doesn't affect function. If rust bothers you, paint the exterior with rust-inhibiting paint before filling.

Filling Your Planter with Soil

Don't use garden soil from your yard—it compacts in a planter and drains poorly. Instead, use a mix of topsoil, compost, and peat moss or coconut coir in roughly equal parts. This blend drains well, holds nutrients, and gives roots room to grow. A 4-by-8-foot planter 12 inches deep holds about 32 cubic feet of soil, which is roughly 1 cubic yard.

If cost is a concern, you can fill the bottom third with coarse wood chips or straw (which breaks down over time and improves drainage), then top it with the soil-compost mix. This saves money and works well for deep planters.

Protecting Wood from Rot

Even with good drainage, wood eventually rots where it touches wet soil. You can slow this by keeping the planter off bare ground—set it on gravel, pavers, or a bed of landscape fabric so air can circulate underneath. You can also paint the exterior and interior with a non-toxic wood sealant, though this adds cost and requires reapplication every few years.

The simplest approach is to accept that a wooden planter has a lifespan and plan to replace it. A pine planter that lasts seven years costs less per year than a cedar one that lasts twice as long, especially if you build it yourself.

Frequently Asked Questions

How deep does a planter need to be?

Most vegetables need 8 to 12 inches of soil. Shallow-rooted crops like lettuce and spinach do fine in 6 inches. Deeper-rooted plants like tomatoes, peppers, and root vegetables need 12 inches or more. A 12-inch-deep planter works for almost everything.

Can I use treated lumber for vegetables?

Modern pressure-treated lumber is considered safe by the EPA, but many gardeners prefer to avoid it for food crops. Cedar, redwood, or untreated pine are safer choices if you're concerned. If you do use treated wood, line the interior with landscape fabric to create a barrier between soil and wood.

What size planter should I build?

Larger planters are easier to manage—they hold more soil, dry out slower, and give roots more room. A 4-by-8-foot planter is standard and fits most garden spaces. If space is tight, a 2-by-4-foot box works for herbs and greens. Avoid anything narrower than 2 feet—it dries out too fast and limits what you can grow.

Do I need to treat the wood with anything?

No treatment is required, but a non-toxic exterior sealant extends the life of the planter. Linseed oil, tung oil, or water-based polyurethane all work. Reapply every two to three years. Without treatment, untreated pine lasts five to seven years; cedar lasts longer without treatment.

Can I build a planter on a deck or concrete?

Yes, but you must drill drainage holes in the bottom so water doesn't pool. Without drainage, roots rot and the wood underneath rots faster. Alternatively, set the planter on spacers (wood blocks or plastic feet) so water can drain underneath.