What to Put in the Bottom of a Whiskey Barrel Planter

We get asked this at the yard more than anything else. What goes in the bottom of a barrel planter? Gravel? A liner? Old pop cans? We use drainage holes, one layer of fabric, and good potting mix. Filler is optional and depends on what you're planting.

Start With Drainage Holes

A bourbon barrel was built to hold liquid, so a half barrel with no holes is a bucket. In a wet Vancouver Island winter, that bucket fills up, the roots sit in water, and the plants rot.

Flip the barrel over and drill 5 or 6 holes, 3/4" to 1" across, spread evenly over the bottom. A sharp spade bit cuts through the 1" thick oak head in a few seconds. Several small holes drain better than one big hole in the middle, and they don't weaken the head boards.

If you bought our planter barrel package, each of the three barrels keeps the original barrel head as its bottom, so the same rule applies to all of them.

Skip the Gravel Layer

Gravel or rocks in the bottom is old advice, and it works against you. Water doesn't move easily from fine soil into coarse gravel. It collects in the soil just above the gravel until that soil is saturated, which raises the soggy zone higher in the barrel instead of draining it. Gravel also adds weight you don't need.

Fill the barrel with the same mix top to bottom and let the drainage holes do the work.

Use One Layer of Fabric, Not Plastic

Cut a circle of landscape fabric to fit the bottom. It lets water out and keeps soil from washing through the holes. That's all the liner a planter needs.

Don't line the whole barrel with plastic. It traps water against the staves, and wood that stays wet rots sooner. The char inside already protects the oak. It held bourbon for years.

How Much Soil a Half Barrel Holds

Our half barrels are about 24" across and 18" tall on the outside. Inside, that works out to roughly 100 litres of soil if you fill it to within a couple of inches of the rim. That's two large bags of potting mix, or three of the smaller ones.

Use potting mix, not garden soil. Garden soil compacts in a container, drains badly, and brings in weed seeds and slugs. If you want to stretch it, mix in up to a third compost.

Should You Use Filler in the Bottom?

It depends on what you're growing.

• Annual flowers, herbs, and lettuce: most roots stay in the top 8 to 10 inches. You can fill the bottom third with upturned plastic nursery pots or a few chunks of untreated wood, cover it with fabric, and save 30 to 40 litres of soil.
• Tomatoes, potatoes, shrubs, small trees, and perennials: use the full depth. They'll use every inch of root space, and more soil means less watering in August.

Avoid pop cans, packing peanuts, and pool noodles. They break down, they're a pain to fish out when you replant, and some of them leach things you don't want near food.

Lift It Off the Ground

If you only do one thing on this list, do this. A barrel sitting flat on soil or concrete never dries out underneath, and that's where rot starts. Set it on pot feet, a few bricks, or a couple of scraps of pressure-treated 2x4 so air can move under it.

Think about placement before you fill it. A planted, watered half barrel can weigh over 100 kg. If you might want to move it for winter or follow the sun, put it on a heavy-duty rolling plant caddy first.

Soak It if It's Dry

Barrels that have been sitting in a dry yard can have small gaps between the staves, and the hoops may feel loose. Hose it down inside and out for a day or two before filling. The oak swells, the gaps close, and the hoops tighten up. If a hoop still slips, put two short screws through it into the stave.

Plant and Feed

Leave about 2 inches from the rim so water doesn't spill over the edge. Bagged mix only feeds plants for a few weeks. A spring handful of slow-release fertilizer keeps things going through the summer, and you can top up with compost every year.

Edibles are fine to grow in a bourbon barrel. The char is just carbon, and the bourbon is long gone by the time we've cut the barrel and it's sat out in our yard. Keep wood oils and sealers on the outside.

Quick Checklist

1. Drill 5 or 6 holes, 3/4" to 1", in the bottom
2. Lay one circle of landscape fabric over them
3. Optional: filler in the bottom third for shallow-rooted plants
4. Fill with about 100 L of potting mix, plus compost if you like
5. Set it on feet or bricks, or on a caddy if it needs to move
6. Plant, water in, and feed in spring

Need a barrel? Our half whiskey barrels are $65, and the three-barrel planter package gives you a staggered set for a patio or entryway. Pickup is by appointment in Errington. For more ideas, see our barrel planter guide or browse barrel planter supplies.