How to Make a Galvanized Stock Tank Planter

Turn a galvanized stock tank into a planter filled with flowers and edible plants!

A galvanized stock tank makes an easy, durable raised garden bed for growing vegetables, herbs, flowers and even small fruits. With a few drainage holes, good soil mix, and a little preparation- you can turn an ordinary livestock water trough into an attractive and productive garden planter.

I’ve used galvanized stock tanks as raised beds in my own garden for years. I originally chose them because I wanted raised beds that were at least 24″ tall and easier for me to reach without so much bending.

Over the years, I’ve learned quite a bit about using stock tanks as planters- including how to prepare them, how much soil they require, what grows well in them, and a few mistakes I wouldn’t make again.

If you’re considering adding a stock tank planter to your garden, I’ll walk you through exactly how I set mine up and what I’d do differently today.

Before You Turn a Stock Tank into a Planter

Choose a Sunny Location

What are you planting and what amount of sunlight is required for those plants? If this is a mini vegetable garden, choose a site with 7-8 hours of direct sun. This was my first mistake with raised bed gardening. Most vegetables will not grow in the shade.

Consider the Height of the Tank

What root depth will your plants need?

• Garlic, spinach and lettuce for example are shallow rooted plants.
• Tomatoes, squash and okra on the other hand, require deeper root depth.

At the same time, consider the height of the mature plant added to the height of your planter. This was the second mistake I made with raised beds. I couldn’t reach the tops of my blackberry plants!

Make Sure a Water Source is Nearby

Dragging hoses and water cans is not fun! Read Easy Step by Step Drip Irrigation for Raised Beds. I explain very clearly how to install a system all by yourself.

Put the Tank in Place Before Filling It

Once tanks are filled with soil, they are very heavy! Plan accordingly because moving them is extremely difficult after filling.

Prepare Your Site

Depending on your site and personal preferences, you may or may not need to do much to prepare. I’ve seen plenty of tanks placed right on the grass or dirt ready to fill.

For our slightly sloped area, we chose to create a large rectangular shaped base layer of gravel and sand to create a level foundation for our three stock tanks with plenty of walking room around them.

Think about the walking space between each tank carefully to make sure you have enough room for a wheelbarrow.

Next we laid out several leftover flagstone pavers where each tank would be placed. This allowed for improved drainage and a solid level foundation underneath them.

Prepare Your Stock Tanks

Drill Drainage Holes in the Bottom

The stock tanks, as you probably know, are actually water troughs for livestock. Therefore, there is a brass plug and drain hole typically on the side for routine cleaning. This drain hole is a few inches up the side and not on the bottom.

For gardening, you will need more drainage than this one small hole on the side. Otherwise, water will sit stagnant in the bottom.

Plan to drill (with a bit designed for metal) several large holes in the bottom of the tank before going any further.

For my stock planters, I recommend:

• Use a 1/2 inch drill bit designed for metal
• Drill holes approximately 6 inches apart across the bottom of the tank
• Use a grid pattern to space them evenly apart
• Wear eye protection and gloves when drilling through metal

Are Galvanized Stock Tanks Safe for Growing Vegetables?

When I purchased galvanized stock tanks for my future vegetable garden, I worried about the galvanization process and whether zinc from the metal could leach into the soil and be taken up by the plant roots.

I learned that galvanized steel is coated with zinc to prevent corrosion and rust.

Zinc is not necessarily toxic. In fact we use it as a mineral to boost immunity and fight off colds.

It does become a problem, however, when inhaled through sanding or grinding. It’s also problematic if corroded through acidic products. This is why we don’t eat off of galvanized utensils.

Read about the galvanization process as explained by the American Galvanizers Association here.

The primary concern with galvanized garden beds is acidic soil. Zinc is more likely to leach from galvanized metal when it is exposed to very acidic conditions. Fortunately, most vegetables prefer soil with a pH around 6 to 7. This is well above the highly acidic conditions where zinc leaching becomes a greater concern.

For vegetable gardening, I prefer to use new galvanized stock tanks rather than old, rusting or repurposed tanks with an unknown history. I also maintain my soil in the normal pH range recommended for vegetable gardens.

If you’re still concerned about the galvanized metal coming into direct contact with your garden soil, you can line the sides of the stock tank with an appropriate barrier. Just remember to avoid covering the drainage holes in the bottom of the tank.

Even though the studies show that new tanks are safe for growing edible plants, I chose to add an extra barrier between the galvanized steel and my soil. I sealed the inside of my tank with a food grade paint that vintners use for winemaking. This particular brand is becoming more difficult to find, but you could explore the Green Design Center for more options.

Prepare or Paint the Stock Tank

I scrubbed the insides of the tanks, rinsed them thoroughly and allowed them to dry completely. Then I painted the interiors with the paint I purchased specifically for this.

For aesthetic purposes, I painted the outside with a white primer and then finished with my favorite creamy white paint, Alabaster by Sherwin Williams.

Have fun with this part! I’ve seen some tanks painted robin egg blue, sunflower yellow and even terracotta red. I think painting birds and flowers on the outside would be darling for a children’s garden. Get creative!

Put the Tank in its Permanent Location

With your site properly prepared, set your planter(s) in place. Check measurements for spacing and adjust if necessary before filling with dirt. Also make one last check to make sure they’re level.

If you plan to use drip irrigation, now would be an opportune time to run the main tubing through the drain hole on the side. It’s not imperative to do it this way, but it would look cleaner to hide the hose from the outside.

If you plan to connect two tanks with a trellis (ie: cattle fence panel trellis), now would also be a good time to add it.

Fill the Stock Tank

Gravel Layer for Drainage

Before adding soil to the planters, add 2-3″ of gravel or rocks in the bottom to help keep the drain holes clear.

If you look at the photo above, you will notice a cinder block placed in front of the drain hole. I made this to attract frogs/toads to help with bugs. Apparently the damp cavern is a natural hideaway for them.

It didn’t work for me, though. In fact, I ended up with wasps in one! Third mistake?

Debris Layer (Hugelkulter Method)

Next add a layer of debris such as dead branches, leaves, lawn clippings (herbicide free), and twigs. These will take up space and break down into natural compost material with time.

• Fill about 1/2 of the tank with debris. In this project, that means 12″ of debris.
• Pack dead leaves and clippings into gaps as much as you can to reduce air pockets.
• If your tank is only 12″ high, you will not have room for branches. But a 2-3″ layer of organic material like twigs and leaves should be fine.

Soil Mix Layer

We still have 1/2 of the tank to fill. Begin with inexpensive topsoil to fill in the gaps of the debris and gravel layers. Keep going until you are 6-8″ away from the top of the tank.

This will be around 6-8 bags of topsoil if they are 2 cubic foot bags.

Understand that the upper zone of the raised bed is your good soil. You want the best at the top for plants’ roots to utilize. I absolutely love Fox Farm Happy Frog Potting Mix. The texture is soft and blended, rich with nutrients and consistently high quality.

I think the toad feels slighted…sad toad?

Fill the rest of the planter with nutrient rich potting mix and compost. I blend these together anywhere from 50-50 ratio to 60-40 ratio (potting mix to compost).

This will be 3-4 bags each of potting mix and compost depending on how dense your debris layer is. Picture soil particles filling in any remaining air pockets between twigs and branches.

I was surprised at how much soil was needed to fill them all the way up!

In my experience, I need to add more compost to my raised beds after each season. Material breaks down and compacts over time. The new compost replenishes the nutrients and builds back up the soil for the next round of plants.

Continue setting up your drip irrigation, if appropriate.

What Can You Grow in a Stock Tank Planter

Even though 12 square feet might seem limited, you can plant quite a bit in this space.

Vegetables

• tomatoes (cage)
• peppers (cage)
• cucumbers (trellis)
• bush beans
• lettuce
• carrots
• radishes
• squash (trellis)

Herbs

• parsley
• basil
• sage
• rosemary
• dill
• cilantro
• thyme
• chives

Flowers

• marigolds
• Nasturtiums
• zinnias
• sweet alyssum
• salvia
• petunias
• verbena

You don’t need a huge garden or complicated raised bed construction to grow food successfully. A simple galvanized stock tank can be simple and productive.

For more information about raised beds, read The Pros and Cons of Raised Beds.

Make gardening easier with Easy Step by Step Drip Irrigation for Raised Beds.

Read about gardening with physical limitations in Gardening with Mobility Issues.