Growing Lettuce For Seed Under Tunnels

A couple of weeks ago I wrote about our challenges producing lettuce seed in a humid climate. By growing lettuce for seed under plastic tunnels, we can protect the plants and seed from the summer rains.

We start off by …

Planting Lettuce Outside

We transplanted lettuce to the field in early May – Merlot in the foreground  and Red Oak Lead in the back (most of the subsequent pictures are taken from the opposite side of these beds) . By the end of June, they had reached full size.

Notice the rebar stakes on the edge of the bed? The rebar will support the tunnel arches. We place the rebar before planting to make sure the beds are parallel and fit under the tunnel.

At the end of June we began …

Building A Tunnel Over The Lettuce

We placed arches over the rebar. (We also removed some lettuces leaves to improve ventilation.)

We dug a 6-8″ deep trench along each side of the tunnel.

We strung a rope along the ridge and anchored it to rebar stakes at both ends. (This picture is from another tunnel.)

And then we covered the structure with plastic.

The sides of the plastic are buried, and the ends bunched and tied to the stake holding the ridge line. I used a pair of clips on both sides to keep the door open.

This structure is a lot simpler than our 100-300′ field tunnels. Of course, if you’ve read about our tunnels, you know what happens next.

Watching The Tunnel Collapse

After a particularly windy day. One end of the tunnel collapsed.

So I went and got a couple of 10-foot 2x4s for …

Bracing The Tunnel

I pushed the collapsed tunnel arch back up and shoved the 2×4 into place.

I attached one end with plumbing straps and a self-tapping screw through the arch.

The other side was braced against the bottom of another arch.

And the tunnel has stayed up since!


Last week the Ste-Anne-de-Bellevue garlic festival was a success. You can see pictures of the Great Garlic Dessert Challenge on the festival’s Facebook page.

Now let’s batten down the hatches and wait for the edge of hurricane Irene to pass through (supposedly a post-tropical storm by the time it hits Quebec) and we’ll see if the lettuce tunnel is still standing tomorrow!

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