Raised Beds for Rainy Northwest Gardens

Ask Northwest gardeners for one piece of advice and many will say: build raised beds. Our long, wet winters and springs leave ordinary garden soil soggy and cold for weeks. A raised bed drains faster and warms sooner, which can mean planting earlier and losing fewer seeds to rot.

Why they work here

• Drainage. Excess water runs out of the bed instead of sitting around the roots. That matters for garlic, strawberries and anything that rots in wet soil.
• Warmer soil. Soil above ground level warms up faster in spring, which helps tomatoes, beans and squash. See why soil temperature matters.
• Better soil from day one. Many Northwest yards have heavy clay or rocky fill. A raised bed lets you start with good soil.
• No walking on the soil. Soil you never step on stays loose, so roots and water move through it easily.

How big

Make beds no wider than about 4 feet, so you can reach the middle from either side without stepping in. Length is up to you; 8 feet is common because lumber comes in that length. Leave paths at least 2 feet wide, wider if you'll use a wheelbarrow.

About 10 to 12 inches deep is enough for most vegetables, especially if you loosen the soil underneath before filling. Go deeper if you have very poor soil below or want to garden with less bending.

What to build them from

• Untreated cedar is the Northwest favorite. It resists rot naturally and lasts many years.
• Metal beds last a long time and warm up quickly in spring.
• Avoid old railroad ties and any wood treated with creosote around food crops.

What to fill them with

A blend of good topsoil and compost works well. Many garden suppliers in the region sell a ready-made "vegetable garden mix." Avoid filling beds with pure compost or with bagged potting mix alone: pure compost can be too rich and settles a lot, and potting mix is made for containers and gets expensive in volume.

Expect the soil level to drop a few inches in the first year as it settles. Top up with compost each spring or fall.

Common mistakes

• Too wide. If you have to step in the bed to reach the middle, you'll compact the soil you built it to protect.
• Too shady. Most vegetables need at least six hours of direct sun; tomatoes and squash want eight or more.
• Forgetting water. Raised beds drain well, which also means they dry out faster in summer. Lay a soaker hose or drip line before you plant. See how much to water.

New to all this? The beginner's guide walks through a first raised-bed garden step by step.