Spiral herb gardens are favourites among both young and old, whether they are placed in your beloved garden, allotment, balcony, or schoolyard. But what makes them so beloved, and how do you properly construct one? 

 

The benefits of an herb spiral 

The moisture-loving parsley, the Mediterranean rosemary, and the wonderfully aromatic lemon balm: these three herbs couldn't be more different in terms of their climate and soil requirements. The three-dimensional structure of an herb spiral allows for the recreation of four climatic zones in a small space, meeting the diverse needs of many different herbs. The herb spiral brings joy to us and serves as a habitat for various small creatures. 

The ideal placement for my herb spiral 

Now that we know why we absolutely must have an herb spiral, what considerations should we make regarding its placement? 

The substrate, the correct placement and orientation are crucial for recreating the four climatic zones in the herb spiral. These factors affect light, shade, and humidity. 

Most herbs prefer sun, warmth, and shelter. Therefore, it is ideal to find a south-facing spot that offers protection from the wind, but it should not be under a tree or in a shaded area for most of the day. It is best if the herb spiral is located close to the kitchen, so the herbs are within easy reach. 

The herb spiral should not be too small if the plants are to have enough space to grow. It should have a minimum diameter of three meters. Sketching the spiral in the chosen location can be helpful to get an impression of its size, and if needed, it is still possible to find a new placement for it. 

Finally, the correct orientation is important. The pond at the end of the spiral should be located to the south, as it influences the individual climatic zones. 

How I Construct My Herb Spiral 

Once the ideal placement for the herb spiral has been determined, we can begin the construction process. First, dig a hole for the spiral, approximately 30 cm deep, and fill it with about 10 cm of gravel. This prevents water from collecting at the bottom of the spiral. Next, dig out a pond about 40 cm deep, which should not be filled with gravel. Instead, insert a pre-formed garden pond or a masonry tub that is 30-40 cm deep, or alternatively, line the hole with foil. Then, fill the pond halfway with sand and pour in enough water to reach the soil at the end of the herb spiral. This creates the wet zone, the first zone of the spiral. 

The next step is to arrange the stones in an upward spiral shape. They should be laid with an increasing slope, so the walls become higher as they approach the centre. There should be a distance of 60 cm between the walls to allow the plants enough space to grow. The central wall should be approximately 80 cm high. Optically, the spiral should resemble a snail shell. The advantage of using stones is that they retain heat, protecting the plants from mild frost. If you rather want to avoid the use of mortar, herbs like thyme can be planted in the gaps, creating a new habitat for small creatures. 

Once all the stones are in place, fill the herb spiral with gravel. To accommodate the planting of herbs in the upward spiral, the amount of gravel should increase as you get closer to the centre. The highest point, the dry zone, should be filled with approximately 50 cm of gravel. From that point downwards towards the end of the wet zone, the layer should be relatively even. 

Prefabricated herb spirals from the hardware store are particularly suitable for balconies. They are significantly smaller and easier to transport. Due to space constraints, these spirals do not have a pond. 

 

It depends on the right soil

Since herbs not only have different climate requirements but also soil preferences, the herb spiral is filled with different soil mixtures. 

In the dry zone at the top, half of the garden soil is mixed with sand. From there towards the normal zone, less sand is used, and instead, compost or topsoil is added. In the wet zone, the soil mixture consists of equal parts garden soil and compost or topsoil. 

 

Adding plants 

Now that all the preparations are complete, the herb spiral is ready to be filled with herbs. Each zone is suitable for different herbs. 

In the water zone, which has a moist microclimate, watercress, broadleaf plantain, and water mint are particularly suitable. 

In the sunny wet zone, chives, peppermint, parsley, and chervil thrive. 

The soil in the normal zone provides Central European growth conditions due to its low content of compost or mulch. Additionally, due to the structure and orientation of the herb spiral, there are some shaded areas in this zone. Oregano, lemon balm, and tarragon are well-suited for this zone. 

The south-facing wall of the herb spiral is heated by the light reflected from the pond. Behind it, the Mediterranean herbs are located in the dry zone. These include sage, thyme, rosemary, and lavender, for example. 

Caring for the herb spiral 

Now, we can finally admire our herb spiral in full splendour with all the herbs. Here are a few tips on how to enjoy and benefit from it for a long time. 

1. Watering

Particularly the herbs in the wet zone like it to be moist, so they need regular watering. The soil should be watered when it has become dry, for example, if there hasn't been rain for several days or if it has been very hot and sunny. In case of prolonged drought, it's also necessary to water the dry zone. The soil dries out faster due to the elevated position of these herbs and the porous nature of the soil. 

2. Fertilizing 

The plants should be fertilized occasionally to provide the herbs with important minerals or improve their resistance to aphids. It's important to apply the fertilizer to the soil only and not touch the actual leaves if they are meant to be eaten. 

3. Pruning 

The herbs need to be pruned to keep them compact and encourage regrowth for the following year. In spring, the shoots from the previous year should be cut back so that only small stubs are visible. However, there are some herbs where you should wait for their flowering before pruning. 

4. Weed Removal 

Weeds should be removed from the herb spiral, just like in any other herb bed, to ensure that the herbs have enough space, light, and nutrients.