How to Build a Garden Box [2020]

How to Build a Garden Box 2020

A garden box can be built by anyone with basic or no woodworking skills. They are easy and inexpensive to build. I built a 4’x2’x8″ wooden garden box for about $25.

Garden Box Materials

A simple garden box doesn’t require a lot of materials or tools to build. It’s basically a rectangular or a square wooden frame held together with screws or dowel pins. It’s a simple structure for supporting soil and plants

You can build a garden box from any of the following materials.

  • Bricks
  • Concrete blocks
  • Wood
  • Galvanized metal
  • Safe Plastics

Brick garden boxes are even easier to build than wood since you don’t need fasteners to hold the sides together. You may choose to use mortar to cement the bricks together or not. If the bricks are larger and heavier, you could just stack them without any type of adhesive. The soil inside will not push them out.

Larger bricks or blocks work even better if they are about 8-10″ high/tall. Be careful when using Cinder Blocks though. Some Cinder Blocks contain Coal Ash which is nasty stuff and toxic. Adobe or concrete blocks will work fine.

4′ x  2′ Wooden Garden Box Materials [Example]

  1. Sides [4′ length] – 2 [2×8 lumber] or 4 [2×4 lumber] pieces 48″ long
  2. Sides [2′ width] –  2 [2×8 lumber] or 4 [2×4 lumber] pieces 24″ long
  3. 3″ Wood Screws – 16 screws needed for 2×4 construction. or 8 screws for 2×8 construction.

Wood – you can use any untreated lumber like 2×4 or 2×6 or 2×8. You can get it cut to length at most home improvement stores like Lowes or Home Depot. You’ll need either 4 or 8 pieces of lumber. If you choose to use 2×4’s, you’ll need to double the pieces so you can stack them 2 high to make the sides 8″ high. 2×8 lumber is high enough so you don’t have to stack them on top of each other.

Wood Choices for Garden Boxes

  • Pine
  • Douglas Fir
  • Redwood
  • Red Cedar
  • Cypress
  • Black Walnut
  • Hemlock
  • Spruce
  • Juniper
  • American Chestnut
  • Yew
  • Catalpa

Any of these wood choices will make an excellent garden box. I like to use standard lumber sizes like 2×4, 2×6 or 2×8. Most home improvement stores will stock these and will also cut them to size.

I looked at 2×4 studs [Douglas Fir] at Lowes and the price was about $5 for a 2x4x92″. The 2″ thick lumber will make these boxes long lasting. It will take 15-20 years before it rots away. If you use thinner lumber like 1″ or less, it will rot through quicker.

Redwood and Cedar will last the longest but they are more expensive. Pine and Douglas Fir are great choices and long lasting…and cheap.

4′ x 2′ x 8″ Garden Box Project

I’m in the process of building a 4′ x 2′ x 8″ garden box. I’m going to use standard Douglas Fir 2×4’s from Home Depot. I’ll need 4 pieces 4′ long and 4 pieces 2′ long for the sides. I want untreated lumber because I don’t want any chemicals to leach into my garden where I’m growing edibles. Douglas Fir or Pine works perfectly.

I’m going to stack 2 2×4 pieces on top of each other to make the garden box 8″ high. I chose 2×4’s because they’re a lot cheaper than 2×8 lumber.

I’m going to fasten the 2×4 sides together using 3″ long stainless steel wood screws. I chose stainless steel because it is a non-toxic metal and will not rust easily. Don’t use any type of glues as they may contain toxic chemicals or may dissolve when wet. You really don’t want glue getting into the soil and then into the plants. It may harm the plants and/or you.

You can use either Philips head screws or the hex head. The hex head are easier to screw and tighten with a nut driver or socket and ratchet. I like the hex heads.

Safe Metal Fasteners

  • Stainless Steel
  • Zinc Galvanized

Recommended Fasteners

  • Stainless Steel Screws
  • Stainless Steel Nails
  • Zinc Galvanized Screws
  • Wood Dowels

**** Be careful what you use to fasten the wood together if you’re going to grow edibles/vegetables

Another safe option is to use dowels to fasten the wood together but it is more work. Drill holes [3/8″] in the lumber and then tap in the appropriate size wooden dowels. I prefer screws though.

When I’m ready to build the box, I’ll pre-drill holes in the lumber for the screws with a 1/4″ drill bit. This makes it much easier to screw a long fastener like a 3″ into hard lumber. If you don’t pre-dill holes, you might crack or split the lumber with the screws.

I’ll use the 3″ long screws to securely fasten the 2×4’s together and I’m basically done. Now I’ll choose a location and prepare the soil.

Best Locations for Garden Boxes

I’m going to select a location in my backyard that has 50/50 direct sun and shade. The Arizona sun can be brutal during the day. Shade will provide cooler temps for vegetables and flowers. I have a block wall that will provide afternoon shade.

Preparing the Garden Box Site

I’m going to use a mixture of native soil and commercial compost for my garden box. This will provide a rich soil that drains well, has good water retention, fertilizes and enhances the Arizona clay soil. Clay soils are pretty poor for growing anything but weeds and Bermuda grass. They don’t drain, are rock hard when dry and have zero organic material in them. Compost will change all of this.

I really like Kellogg’s garden products like N-Rich and All Natural Garden Soil. They are 100% organic and reasonably priced at $8.98 per 3 cubic feet bag. These bags are compressed, so you get a lot more than what it looks like in the bag.

You can use any commercial organic compost, garden soil or composted manure. You can also mix the soil anyway you like from 100% compost or commercial garden soil to 50% compost and 50% native soil or even 25% compost/garden soil and 75% native or yard soil. All of these will work really well. I prefer the 50% compost mixed with 50% native soil. It has worked fantastically for me.

First I’m going to till or dig up about 12″ of the soil in the garden box location. This will break up the compacted dry soil and make it easier to mix with the compost. I use a claw hammer to break up the soil. Claw hammers are the best gardening tools.

Now, I’ll put the garden box frame in place. I like to wet the bottom soil to help soften it. The compost will help with that too. I’ll dump some of the N-Rich Soil conditioner compost in the box and mix the soil with it thoroughly. I keep adding and mixing. I want to try to keep it a 50/50 mix of compost and native soil. If it looks like too much compost, I’ll add more native soil from my yard.

After the garden box is full, I level it off and water thoroughly. I won’t plant anything for 3 weeks. I water regularly to promote bacteria and microbe growth. Soil is an ecosystem full of microorganisms and insects. It takes a few weeks for this ecosystem to grow and stabilize. After 3 or 4 weeks, I’ll start planting seeds.

Garden Box Benefits

So why build a garden box instead of just making a garden on the ground?

Easier Garden Soil Setup
A garden box makes it easy to have rich, organic soil that will make a vegetable garden produce beautiful fruit and lots of it. It also makes the best flower gardens too. It’s as easy as dumping rich soil into the box and then plant. A ground garden is not so easy.

If you make a garden on the ground you are limited to the native soil or you have to spend a lot of time preparing the soil. In order to prepare native soil for gardening, you might have to till or turn the soil so that you can mix in organic material. Tilling dry, compacted soil is difficult and time consuming…and back breaking. I’ve tilled many gardens in my time and choose not to anymore. My back thanks me too.

Anyway, you need to dig up the soil and mix it with compost before planting anything. This is no easy task.

Weed and Grass Control
Garden boxes also separate the garden from the rest of the yard which means, weeds and grass won’t invade the garden. A ground garden will get invaded by weeds and grass. Weeds will drop seeds in the garden and sprout quickly. It’s much harder for weed seeds to get into a raised box garden. If weeds do get into the box garden, they are very easy to pull out because the soil is moist and soft.

Keep Pests Out
A raised garden box also repels pests from getting in your garden because its more difficult to get into. Rabbits and cats will be more likely to stay out of a garden box because it’s elevated off the ground and harder to access. Rabbits love to eat your plants and will demolish a lettuce garden in no time. Cats love to dig and poop in soft soil. The raised box will deter them from climbing in.

Easier Maintenance

It is easy to do garden maintenance when the garden bed is raised off of the ground by 12-24″. You don’t have to bend over as far or sit on your knees. Plucking any weeds will be a snap.

Garden Boxes are Decorative
Garden boxes also add visual appear to your front or backyard. They are very functional and decorative. Nothing looks more organized and pleasant than several raised wooden box gardens.

Can Pick Locations
You are able to pick any location for a garden box site. You can even build one on top of your patio. You get to choose the location unlike a ground garden where you are limited to available space in your yard.

A garden box is also temporary or mobile. You can move one if you need to. Just empty it of soil, pickup the frame and move it to a new location. You can’t do that easily with a ground garden.