Acidic soil plants – how to create an acidic soil bed

All acid soil plants thrive in moist, rich soil with a low pH value, i.e. acidic soil. If you own a forest plot, the soil is often naturally acidic due to the decaying bark from the trees. But you can plant acid soil plants in other places as well, you just have to make the soil more acidic where you want to plant them. The most effective is to create an acid soil bed where you collect several acid soil plants. This will make the plants easier to care for, and they actually also thrive better in groups.

You can plant perennials in the acid soil bed as well, but make sure that there are perennials that want, or at least tolerate, acidic soil. Examples of such perennials are Japanese spearmint, arends spearmint, small heart, lieutenant's heart, alum root, ferns and various types of primrose.

If you don't have naturally acidic soil, you can make it yourself by mixing the soil on site with coarse, shredded peat. The soil will be even better if you also mix in some compost and gravel (2–5 mm) as well as pine and spruce bark. Compost made from oak and beech leaves can also be used. Oak leaves decompose slowly, but in this case it is actually an advantage. It is also possible to buy acidic soil, for example Plantasjens Rhododendron soil.

Photo: Liselotte Roll

Some acid soil plants thrive in sun and others in shade, but a bright, west-facing location sheltered from the wind works for most people – bright, but not in the middle of the sun. If you don’t have a natural spot facing west, you can create one by protecting it from the wind, putting up a willow fence or planting a hedge. In this way, you also create a favorable microclimate. It is usually natural to plant the acid soil bed next to the house, a large rock or a beautiful tree. In some places it is possible to find a suitable place on a forest slope or similar. What you should try to avoid is placing the bed in the middle of the lawn, without protection from the weather and wind.

Some plants require a lot of sun, while others (such as hosta) do well in the shade. Choose plants that thrive where you are going to plant them.

Once you have chosen the location for your acidic soil bed, you can either dig it out or build it on a raised bed. The latter is often the easiest. If you build on a raised bed, you can use peat blocks, stones or logs as edges. The bed should be at least 30 cm deep, but preferably 50 cm – this is where almost all acidic soil plants thrive. Place thick cardboard at the bottom to smother any weeds.

Also read:
No-dig perennial bed – create a new bed without digging

A bed of acidic soil holds water well. You should water during the establishment phase, when the plants are developing roots, but after that you only need to water when the soil is dry. If you have made borders of peat blocks, however, you can water these properly for the first few years.

If there is a lot of lime in the water where you live, it is better to water with rainwater, which is naturally acidic. You can also choose plants that shed their leaves in the winter, as they store less lime.

Very little fertilizer is needed in an acidic soil bed. And if you are going to fertilize, it is rhododendron fertilizer that applies. You can also put a very thin layer of compost on top of the bed about once a year.

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