Installing railroad ties starts with a level trench and compacted base, then staggered courses pinned with rebar or spikes.
Installing railroad ties for landscaping starts the same way whether you are building a raised bed or a retaining wall: a level trench, a compacted base, and anchors that hold. Get those three right and the wall stays put for years. Here is the sequence that works, along with the mistakes that cause failures.
How Deep Should You Dig the Trench?
Map the shape with stakes and string before any digging. Walk the line and adjust the curve or corner until it looks right — a garden hose laid on the ground helps visualize the shape. Call your local utility locator at least a few days before breaking ground; the service is free and prevents hitting buried gas, water, or electric lines.
For a single-course border used as edging, dig the trench deep enough to bury one-third to one-half the tie height. For a retaining wall, go deeper: the first course needs to be fully buried, plus an extra 4 to 6 inches for a gravel base. Make the trench about 6 to 8 inches wider than the ties so you have room to work and adjust. Compact the bottom with a hand tamper or a plate compactor — a rented plate compactor is worth the cost for any wall longer than 10 feet. Skipping compaction is the most common reason walls settle and tilt within the first year.
Set the First Course on a Compacted Base
Spread 4 inches of crushed stone for decorative edging or at least 6 inches for a retaining wall. Compact the gravel in lifts — each 2 to 3 inches thick, tamped thoroughly before the next goes on. A plate compactor delivers more uniform results than a hand tamper and is worth renting for larger projects.
Set the first course of ties on the gravel and check level both front-to-back and side-to-side. Use a long spirit level — a 4-foot level shows dips that a shorter one misses. Add or remove gravel under low spots to bring the tie level; shimming with dirt later will settle and throw the wall out of alignment.
Drill anchor holes about 12 inches from each end of every tie. For ties longer than 4 feet, add a center hole as well. A hammer drill with a 5/8-inch bit makes clean holes through creosote-soaked wood. Drive anchors through the holes into the ground below. Use 1/2-inch rebar in 18- to 24-inch lengths for standard walls, or 2-foot sections for taller walls with higher lateral load. Ten- to 12-inch galvanized steel spikes also work and drive faster in firm soil. Rebar gives better holding power in loose or sandy ground — cut it with an angle grinder before driving if needed.
Stack and Anchor Railroad Ties for Landscaping Walls
For walls more than one course tall, stagger the joints — the seam in the row above must never line up with the seam below. Drill and pin each upper course to the layer beneath using the same hole pattern: 12 inches from each end, plus center holes on ties over 4 feet. Each layer locks the one below it.
Behind any retaining wall, drainage is non-negotiable. Add at least 12 inches of gravel or crushed stone backfill against the wall, and lay a 4-inch perforated drainage pipe at the base that routes water away from the structure. Wrap the pipe in filter fabric to keep soil out. Without drainage, hydrostatic pressure builds up behind the wall and pushes it outward — often within the first two seasons.
Keep railroad-tie walls at 4 feet or under. Walls over 3 feet tall require deadman anchors — T-shaped anchors driven into the slope behind the wall and tied back to the face with galvanized cable or rebar. For walls approaching 4 feet, consult a structural engineer or switch to engineered retaining-wall blocks designed for that height.
| Anchor Type | Recommended Length | Placement |
|---|---|---|
| 1/2-inch rebar (standard wall) | 18–24 inches | 12 inches from each end |
| 1/2-inch rebar (tall wall) | 2 feet | Ends plus center if tie is over 4 ft |
| Galvanized steel spike | 10–12 inches | 12 inches from each end |
| Deadman anchor (T-style) | Varies by height | Required on walls over 3 ft |
Old or surplus ties often contain creosote, a possible human carcinogen that is not registered for garden or home use. If you are building vegetable beds, choose untreated hardwood or composite timbers instead — see the best railroad ties for garden beds for options that work without chemical risk. This point is reinforced in Gurney’s safe-use guide, which notes these ties were designed for railroad beds, not garden beds.
FAQs
Do I need gravel under railroad ties?
Yes. Gravel provides drainage and a stable base that resists settling and frost heave. Without a compacted gravel layer, soil beneath the ties shifts with rain and freeze-thaw cycles, causing the wall to lean or sink. A 4- to 6-inch layer of crushed stone is standard for retaining walls.
Can I build a retaining wall over 4 feet tall with railroad ties?
Not without engineering review. Railroad-tie retaining walls are generally limited to 4 feet in height. Walls over 3 feet need deadman anchors tied back into the slope, and anything near 4 feet benefits from professional structural design. Taller walls require engineered block systems or reinforced concrete.
Are railroad ties safe for vegetable gardens?
Creosote can leach into garden soil and is classified as a possible human carcinogen. Use untreated landscape timbers, composite materials, or natural stone for edible garden beds.
References & Sources
- Gurney’s. “How to Safely Use Railroad Ties for Landscaping.” Notes creosote ties are not registered for residential garden use.