Many gardeners are looking for ways to use space efficiently and get the most out of a given area, and at the same time create the best environment for their plants. Every garden should have herbs, but sometimes they can be tricky to grow. They want different kinds of soil, so putting them all in one bed doesn’t always work. Some are perennial and some annual or biennial. Some demand full sun and some can benefit from a bit of afternoon shade. Most want great drainage. And of course they take up space. What’s one solution? An herb spiral.
An herb spiral is basically a raised bed in an interesting shape that creates planting areas of differing depths, sun exposures, and (if desired) soil textures. You can learn how to build an herb spiral from about a bazillion articles and videos online; here are two I found with good instructions. You can use many different materials including stone, brick, and various building blocks. It all depends on the look you want.
This is my spiral a couple of years ago when it was first built (thanks to my son Nick). You can see it sits on a gravel area behind a shed. You can also construct one on soil or on an area that’s currently lawn; if the latter you might want to remove sod first or use cardboard to block the growth of grass, and make sure you mulch around the perimeter to make mowing easier.
When you fill the spiral, you can use different soil types, some rich with compost, some sandy or gravelly, to suit the ideal growing conditions of the herbs you plant there. Pay attention to light exposure. Because of the shed, the back of my spiral gets less sunlight, so any herbs I plant there are shaded in the afternoon. This is a good place for herbs that prefer cooler weather, or that grow tall quickly so they’ll still be exposed to light. The top of the spiral is good for Mediterranean herbs that want great drainage, drier soil, and full sun. The moister soil near the bottom is better for annuals like basil.
You can see a small plant (I forget what it was) poking out between the blocks in the front. This was a failed experiment; soil pockets between the blocks were too small to support growth. But you could design your spiral to include access between stones or bricks to the interior and have herbs cascading from the sides. This is a very flexible concept and the possibilities are endless.
By the way, the slope behind the spiral, which is mostly gravel mixed with some clay loam, has turned out to be that elusive spot in which rosemary will grow well for me.
The reason that rosemary conks out for many of us in this region isn’t the cold spells in the winter so much as the freeze-and-thaw cycle of our early spring, and all the rain we get during that time that sits in the soil and rots the roots. It also doesn’t love soil acidity. A mostly gravel soil is working great for me, at least for the past couple of years; we’ll see how long the experiment lasts. It also helps that the north winds are blocked by the shed. I love rosemary, and am always jealous of those great hedges that folks in the south and near the shore seem to manage without trying, so I’m hoping for tall, beautiful, and truly perennial plants.
Another Mediterranean herb that does fine in mostly gravel is oregano, which has escaped the spiral and is populating the area around it. If you don’t demand an entirely tidy look, see what plants seed themselves and spread outside of your spiral. And definitely let your herbs bloom; bees love to visit the flowers. (Basil you might want to keep trimmed back since the flavor is best in plants that haven’t bloomed. And remember to give basil plenty of room for air circulation to keep downy mildew down. Or use the new resistant cultivars.)
This is a fun project that enhances the look of your garden and doesn’t have to be super-expensive, especially if you can use scrap bits of stone you or someone you know may have lying around. Tall thin spirals, flat wide spirals, wall-like spirals built with great precision or messy ones where the shape can barely be discerned: there’s room for all. And then you get to go shopping for herbs, which is the most fun of all.
By Erica Smith, Montgomery County Master Gardener