The voracious slugs clean entire rows of lettuce (and freshly planted young plants…) completely bare within a very short time and thus cause great damage. Although a snail infestation is less likely in the raised bed than in beds close to the ground, it is not impossible - the animals have no problem crawling up the vertical walls and getting the fresh green fodder they are hoping for.
Snails are easier to keep away from the raised bed
Plan snail protection when building the raised bed
For this reason, you should keep the climbers away by building a slug-unfriendly raised bed. When constructing, make sure that the bed box gets bigger and bigger towards the top - i.e. has a conical shape. This makes it very difficult for the animals to get up. You can achieve such a shape not only with wooden, but also with stone or plastic beds. In addition to the conical shape, life is also made difficult for snails by the bed walls made of overlapping wooden boards (or plastic panels…), because the vermin cannot overcome these angular obstacles, or only with a lot of luck. You can also mulch the soil around the raised bed with sharp-edged wood chips - these are also avoided.
No chance for snails in the raised bed
Otherwise, make your raised bed safe from the voracious molluscs with copper strips stretched around the bed and/or a classic snail barrier. An angled sheet of metal protruding from under the overhanging edge of the bed is sufficient as a snail barrier. Since it can also happen that there are snail eggs on purchased young plants or in the potting soil or in the compost, you should have an environmentally friendly iron-III-based slug pellet (7.49€) ready just in case. A single treatment of the plants in the spring is usually sufficient to have peace from the annoying snails for the rest of the gardening season.
Be careful with overhanging shoots and tendrils
Care should be taken with all overhanging plants in the raised bed: If tendrils of nasturtium, cucumbers, zucchini, etc. on the ground, even the best snail defense is useless. In this case, the animals simply use the overly long shoots of the plants to get to the raised bed. So keep such overly long shoots short, tie them upwards and / or let the plants grow up on a trellis.
tips
Mulching with straw or similar materials not only keeps the soil in the raised bed moist for longer, but also keeps annoying snails away - they don't like the sharp edges and cannot overcome them.