Is Bark Mulch Good Or Bad For Plants?

Is Bark Mulch Good Or Bad For Plants?

We all know it. Finally, the long-awaited bed is ready and planted. The perennials are exactly where they belong and everything looks so nice and tidy. Of course we wish that this condition lasts as long as possible. In recent years, therefore, mulching of freshly planted beds has become more and more popular.

In principle, this is also a good idea, because a layer of mulch has many advantages. For example, it keeps moisture in the soil longer and prevents the soil temperature from fluctuating greatly. In addition, bark mulch or gravel can make it more difficult for weeds to take over the beautiful planting area. However, not every mulch material is suitable for every plant or new planting.

Forest (edge) plants love bark mulch


Bark mulch is particularly well suited for mulching tree discs or unvegetated areas under woody plants that drain water well into the subsoil and thus do not tend to become waterlogged. Here, its positive properties benefit the usually robust plants.

Perennials that are used to growing near or even directly under deciduous trees or shrubs are also grateful for a protective layer of bark mulch over their root zone. With falling leaves or fruit slowly decomposing into valuable humus, these often very nutrient-demanding plants rarely lack forage. It is important for them that new nutrients keep entering the planting area.

Typical forest (edge) plants also love acidic soils. Many deciduous trees have stored so-called tannic acids in their leaves, which are released when they decompose. This also applies to pine bark, which is mostly used for bark mulch.

Once soil organisms begin to decompose the mulch, the acids are released into the soil and the pH drops into the acidic range. This is beneficial for most plants that naturally occur in the woody or woody edge area. But they also have a problem with a special feature of bark mulch.

In order to gradually decompose the pieces of bark, the little helpers in the soil need a lot of energy. They get it from the soil in the form of nitrogen. This would actually not be a problem, but the greedy creatures leave hardly anything for the plants. For this reason, you should always make a compensatory fertilization with horn shavings before using bark mulch. This way you ensure that there are enough nutrients in the soil for both the plants and the soil organisms.

Pro tip…

“A compensatory fertilization with horn shavings against nitrogen deficiency.”

The soil organisms gradually decompose the bark pieces into valuable humus. To do this, they need a lot of energy in the form of nitrogen. But the plants also need it to grow! To ensure that there is enough for all, the planting area is fertilized with horn shavings BEFORE mulching.

These like bark mulch

  • rhododendrons
  • most ferns
  • Caucasian forget-me-not (Brunnera macrophylla)
  • Forest asters (Aster divaricatus)
  • Bergenias (Bergenia)
  • Hosta (Hosta)
  • Wood anemone (Anemone nemorosa)
  • Astilbes
  • Hydrangeas
  • Solomon’s seal (Polygonatum)
  • Rodgersia (Rodgersia)
  • Fairy flowers (Epimedium)

Don’t use bark mulch for sun worshippers on dry soils


Unlike our forest (border) plants, perennials and woody plants from sunny, warm and especially dry areas do not like bark mulch very much. Those that normally grow in steppe, prairie, or rock or gravel gardens and need nutrient-poor, calcareous soils with a high pH for healthy growth don’t do well with the properties of bark mulch. If these sun-worshippers had to grow in an area that dried poorly because it was covered with pieces of bark, their roots would rot and die after only a short time.

You will do steppe plants & co. some good if you cover the bed with a layer of nutrient-poor gravel or chippings after planting. The mineral mulch layer allows water to seep away quickly and the roots of the plants are not in danger.

Remember…!
“The respective mulch layer influences the pH value of the soil!”

Bark mulch lowers the soil pH into the acidic range. Ideal, therefore, for all forest (border) plants.

Limestone grit enriches the soil with lime, raising the pH. Well suited for sun-loving perennials on dry soils.

We dont like bark mulch

  • Sedum species
  • Spurge species (Euphorbia)
  • Yarrow (Achillea)
  • Spur flower (Centranthus)
  • Spanish daisy (Erigeron)
  • Man’s litter (Eryngium)
  • Elecampane (Inula ensifolia)
  • Catmint (Nepeta)
  • Lavender
  • Scented nettle (Agastache)
  • Girl’s eye (Coreopsis)
  • Magnificent candle (Gaura)
  • Sage (Salvia)
  • Scabiosa (Scabiosa)
  • Delphinium (Delphinium)
  • Sunflower (Helenium)
  • Sun eye (Heliopsis)
  • Lupine (Lupinus)
  • many Mediterranean herbs
  • most ornamental grasses
Is Bark Mulch Good Or Bad For Plants?

Bark mulch can cause damage to young plants


Even though many garden owners swear by it – the bag with the bark mulch should better stay in the garage for freshly planted perennials for now. The young plants are still sensitive and are quickly damaged by the many tannic acids contained in the bark pieces.

In addition, the decomposition of the mulch removes a lot of nitrogen from the soil, so that the freshly planted perennials do not grow properly and are left to fend for themselves. In the worst case, there is even the threat of complete failure of the plants.

It is better to wait with the application of the bark mulch until the perennials are well rooted and have sprouted vigorously. And always remember: not every plant can also like bark mulch. Therefore, only spread the mulch where plants are growing that will also benefit from it!

Conclusion: Only the right mulch material brings the desired success.


Mulching beds is about more than just a clean look. Every mulch material has an effect on the soil and therefore indirectly on the plants growing in it. If you keep this in mind in the future and adjust the mulch layer for your beds to meet the needs of the plants, you will have already done a lot for healthy plant development.


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