Last updated on October 25th, 2023 at 12:57 pm
Plants that grow under woody plants do not have it easy. They have to withstand drought, shade and the pressure of large roots. Anyone who wants to plant under trees therefore faces a special challenge. This starts with the choice of plants: Not all ground covers and perennials are made for strong competition. Especially under shallow-rooted shrubs and trees, tender little plants have a hard time. But there are good solutions even for such extreme cases. Here you can find out what to look out for, which plants are particularly suitable and how to create good conditions.
Underplant large trees: These differences are important
Woody plants are the backbone of the garden. It is not easy to establish other plants permanently under trees and shrubs. Especially if the woody plants are already several years old: Dense canopies, as in the case of horse chestnut and beech, hardly let any light through. In addition, the canopy keeps precipitation out, which ensures dry soil. In addition, the underplanting has to cope with root pressure and constantly compete for water, nutrients and space. If you want to underplant trees in your garden, you should therefore first look at the root system of the woody plants.
Three different root systems
Shallow-rooted trees with a dense network just below the soil surface are particularly difficult to underplant. Shallow-rooted trees include birch, spruce, hazelnut, magnolia and Norway maple.
Underplanting deep-rooted trees – this is less problematic. Deep-rooted trees are, for example, rowan, pine and fruit trees such as apple, cherry and plum as well as their ornamental forms.
Heart-rooted trees such as maple, lime and yew are also easy to underplant. They also root quite shallowly, but usually have few main roots that are only more strongly branched at the ends.
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Underplanting trees: With these plants it works
The list of suitable shade perennials that can be used to beautify previously neglected garden areas is long. Woody perennials are particularly recommended for anyone who wants to plant under trees and other woody plants. This is obvious because they are, after all, naturally adapted to the difficult conditions. Tender spring geophytes such as wood anemones, yellow wood anemones and liverworts take advantage in spring when the deciduous trees are still bare and their branches still let in enough light. They also cope well with drought. However, they do not like it so much under conifers. Lily of the valley, ferns (for example Athyrium niponicum), wild garlic or woodruff complete the woodland planting.
Always bear in mind the requirements of the perennials in terms of soil moisture. It is driest on the north side of the tree slice in the immediate vicinity of the trunk. Hardy, drought-tolerant perennials such as Balkan cranesbill, brown cranesbill, ivy flower, golden strawberry and wood aster do well there. Small periwinkle and the well-tried ivy are ideal ground covers for the shade that quickly form dense carpets – and on top of that they are absolutely easy to care for.
Further out, at the edge of the root disc, you can plant species that like it a bit wetter, for example, funkias, bergenias, carnationworts, daisy, purple bells, and star umbels. A tip for all those who want to plant trees underneath and bring other design aspects into play: Shade grasses such as Japanese gold ribbon grass or woodland sedge elegantly play around the large tree trunks. The grass-like snakewort is also suitable for this purpose and delights with a variety of species and pretty flowers. Even smaller shrubs can be planted under giant trees. Mahonia and boxwood provide variety and cope well with root pressure.
Suitable species for underplanting:
- Wood anemone (Anemone nemorosa)
- Yellow anemone (Anemone ranunculoides)
- Liverwort (Hepatica nobilis)
- Lily of the valley (Convallaria majalis)
- Japanese rainbow fern (Athyrium niponicum)
- Wild garlic (Allium ursinum)
- Woodruff (Galium odoratum)
- Balkan Cranesbill (Geranium macrorrhizum)
- Brown cranesbill (Geranium phaeum)
- Elfflower (Epimedium)
- Golden strawberry (Waldsteinia geoides)
- Wood Aster (Aster divaricatus)
- Small periwinkle (Vinca minor)
- Ivy (Hedera helix)
- Hosta (Hosta)
- Bergenia (Bergenia)
- Purple bellflower
- Clovewort (Geum coccineum)
- Magnolia (Astilbe)
- Starthistle (Astrantia major)
- Japan golden ribbon grass (Hakonechloa macra)
- Woodland Lemur (Deschampsia)
- Mahonia (Mahonia aquifolium)
- Boxwood (Buxus sempervirens)
- Hazel root (Asarum europaeum)
- Spring pea (Lathyrus vernus)
- Spotted dead-nettle (Lamium maculatum)
- Solomon’s seal (Polygonatum biflorum)
- Snakeweed (Ophiopogon)
Practical tips for underplanting trees: Preparation and aftercare
Soil preparation plays a major role in ensuring that a tree slice is permanently green and flowering. In addition, a good water supply and the right choice of plants are important for underplanting trees. Late summer is the best time for underplanting woody plants. The trees have almost finished growing and no longer draw so much water from the soil. Perennials, grasses and shrubs have enough time to grow in properly until winter.
Apply about three centimetres of compost and plant the plants. Then water the area well and mulch afterwards to keep the moisture in the soil. Suitable mulch materials include shredded prunings from shrubs and hedges, bark mulch or leaves.
Underplanting trees when the soil is densely rooted?
This is a special challenge, but there is a solution. Heavily rooted soil under old trees cannot be dug up with a spade without damaging the roots. However, it can be loosened carefully with a digging fork. Mark the areas that are barely rooted with a small stick.
Important, so that the perennials grow well: In the near future, make sure that the soil is evenly moist and water additionally if necessary. The fallen leaves in autumn can be left lying around. It serves as winter protection and the resulting leaf humus provides the plants with optimal nourishment. Remove oak and walnut leaves in early spring at the latest because of their growth-inhibiting effect. Do not leave all the needle litter lying around, as it contributes too much to soil acidification.
The hardship case: shallow-rooted trees and shrubs
Under shallow-rooted trees, the root felt is often very dense. It is therefore best to plant rhizome-forming or climbing species such as ivy or cranesbill at the edge of the tree disc. Over time, they will spread towards the trunk all by themselves. In this way, trees can also be underplanted that do not initially appear to be suitable due to their root system.
Another option is to raise the soil level by adding planting soil or compost (approx. 15 to 20 centimetres) so that there is room for planting smaller plants such as perennials or ground covers under shallow-rooted trees. However, at least thirty centimetres around the trunk should be left free.