How to build an herb spiral

So, you are thinking of building an herb spiral? Find out all about building a spiral herb garden, including what to consider regarding the location and orientation, the steps involved as well as which herbs are most suitable.

Whether in the garden or on the balcony, herbs are a must for many gardeners. After all, they not only enrich our cuisine, but they are usually quite easy to grow too. In recent years, raised spiral garden beds have become increasingly popular. The advantages are obvious – herb spirals both save space and allow you to cater to the needs of various herbs by providing different microclimates and soil conditions. Read on to learn how to build a spiral herb garden and get some helpful tips along the way.

Building an herb spiral: location and orientation

Before building an herb spiral, you first need to choose a suitable location. As most herbs require plenty of sunlight and warmth to grow, a full-sun location is best. The orientation of the herb spiral is also very important. The spiral should open towards the south so that all the herbs can bask in the sunshine.

Herb spirals in the garden

Herb spirals are usually placed in the garden. After all, as space-saving as they are, they also need enough room to accommodate all the plants. A design that is 80 centimetres high with a diameter of three metres has proven to be particularly suitable. This way, the herb spiral is still a manageable size, while providing the herbs with enough space.

There are various ways to create an herb spiral garden. The most popular way is using ready-made kits made from plastic or metal − these only need to be set up on site and filled with substrate. With wooden herb spirals, it is important to use a wall protection sheet to prevent the wood from rotting. You can also build your herb spiral out of stones, but this option is more time consuming. A dry stone wall arranged in a spiral-shaped support not only looks attractive, but also provides shelter for lizards or beneficial insects such as wild bees. You can also create a small pond at the foot of the herb spiral so that moisture-loving herbs also feel at home. If you plan on adding a small pond, pay special attention to the orientation of the spiral – the pond must be on the south side. It is also a good idea to place a grid under the herb spiral, just as you would when building a raised bed. This serves as protection against pesky voles.

Tip: If you build a stone herb spiral yourself, use concrete to marry the small stones or bricks together. Otherwise, soil and growing plants will push the wall apart. However, consider leaving the occasional generous gap to allow insects and reptiles to easily move between the stones.

Herb spirals on the balcony

Herb spirals on balconies are still rare, but they are gaining popularity. Unfortunately, not every balcony is suitable for an herb spiral. In addition to needing sunny southern exposure, the balcony also needs to be large enough to provide enough space for the spiral. Furthermore, not every building material is suitable for the balcony. Avoid heavy materials, such as natural stone and concrete, as these can quickly overwhelm the load-bearing capacity of the balcony. We recommend plastic herb spirals for balconies instead as they are particularly light weight. A stable plastic plate is also preferable as a base. The plate should have raised edges to prevent soil and irrigation water from overflowing and creating a mess on your balcony.

Herb spiral design

Once the herb spiral has been set up, you can finally start filling and planting. Before you can get planting, though, there is still a little planning to be done. Aside from needing the right soil for your herb spiral, you will also need to plan ahead to ensure you plant all herbs in accordance with their individual location requirements. Read on to find out how to prepare the substrate correctly and what you need to bear in mind when arranging the herbs.

Soil for herb spirals

Since herbs are considered to be quite easy to care for, many people assume that you can simply fill an herb spiral with normal garden soil. However, like raised beds, herb spirals are also divided into several layers. First, create a drainage layer at the bottom of the herb spiral using gravel, expanded clay or crushed stone as drainage material. Depending on the size of your spiral, the drainage layer should be about 50 centimetres high in the middle and slope down to about 10 centimetres at the end of the spiral. Fill the rest of the spiral with an herb soil, such as our Plantura Organic Herb & Seedling Compost. In contrast to all-purpose compost, herb soil is lower in nutrients to ensure that herbs with low nutrient requirements also do well in it. If you want to plant herbs with high nutrient requirements in your herb spiral, fertilise the soil around these plants as needed. You can also create microclimates by mixing compost into the soil at the base of the spiral or mixing in some sand or sandy garden soil at the highest point of the spiral.

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Tip: Good things take time. After filling your spiral with soil, you should wait a few days and water the soil as the soil may sink. If it does sink, add more soil to even out the terrain. After this, you can finally start planting your herbs.

Which herbs are suitable for herb spirals?

The herb spiral is built and ready to go – it is time to get planting! But which herbs are suitable for the layout? With a few exceptions, most herbs can reside in the herb spiral, as it offers different site conditions for the plants’ varying needs. Mediterranean sun-loving herbs, for instance, grow best in the dry and sunny area at the top of the spiral. Herbs with moderate sun and water requirements grow particularly well in the semi-shaded, middle area. Moisture-loving herbs feel particularly at home at the foot of the herb spiral.

Tip: See our articles on herbs for shade, herbs for partial shade and herbs for sun to find out more about which herbs are suitable for which location.

Which herbs should you avoid planting in an herb spiral? There are only a few to avoid, including plants that tend to grow fast and take up a lot of space, such as lovage (Levisticum officinale) and comfrey (Symphytum). Herbs that have strong root growth can endanger the stability of dry stone walls − these should also be left out of the lineup. That said, although almost all herbs feel at home in the herb spiral, not all species get along.

For an overview of herbs that are compatible with one another, check out our article that charts which herbs go well together.

Herbs for herb spirals

Planting an herb spiral can be a tricky business as there are numerous herbs to choose from. To give you a hand, we have created a planting plan that suggests possible plant combinations for the different climate zones.

The uppermost zone, also called the dry zone, has dry, nutrient-poor soil and gets full sun. Here it is best to plant Mediterranean herbs such as rosemary (Rosmarinus officinalis), thyme (Thymus vulgaris), sage (Salvia officinalis) or marjoram (Origanum majorana). Lavender (Lavandula angustifolia), hyssop (Hyssopus officinalis) and mountain savory (Saturejamontana) also feel at home here.

The temperate zone has semi-shady light conditions. Fresh aromatic herbs grow particularly well here. In addition to the classics like chives (Allium schoenoprasum), coriander (Coriandrum sativum) and mint (Mentha), lemon balm (Melissa) and burnet (Sanguisorba minor) also thrive in this zone.

Caution: Mint is an invasive plant that spreads via creeping rhizomes. If you want to plant mint, put in a root barrier to prevent it from taking over your herb spiral.

In the lowest area, moisture-loving herbs flourish. Parsley (Petroselinum crispum), dill (Anethum graveolens) and wild garlic (Allium ursinum) prefer the upper end of this area in the herb spiral. Watercress (Nasturtium officinale) and sweet flag (Acorus americanus), on the other hand, prefer the very moist bottom. If you have added a small pond at the bottom, water caltrop (Trapa natans) can even thrive directly on the water.