Last updated on April 25th, 2022
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Clay soil has a reputation for being hard and unsuitable for plants, but that is simply not true. Clay soils work quite well in gardens and in fact, bring rich nutrients to your plants. So whether you have clay soil, or think you do, rest assured that there are ways you can fix it, break it up, and grow perfectly stunning shrubs, trees and plants that do well in such conditions.
What is clay soil?
For starters, clay soil is a soil structure made with fine particles, all of which are close together. That compaction prevents air and water from easily moving through, which makes drainage a big problem.
In fact, with this type of soil structure, waterlogging is common and for many plants, this can rot the roots. It also makes the soil physically heavy, so weaker and softer plants cannot cope. Being heavy, it is also a laborious challenge to dig up and takes a lot longer to warm up when spring hits.
You can use a simple soil test kit to determine whether you have clay soil, and from there decide whether you either want to;
- To amend the soil
- To find plants suitable for the soil
Amending clay soil to improve what you can grow
If you have clay soil you can make improvements with time. The biggest issue you will come across is poor drainage. You want to avoid standing water, and to do this, you need strength and time. Start by digging the soil up very deeply and adding bulky pieces of organic matter throughout. Coarse grit, well-rotted wood chips, leaf mould, all work well to break it up. Don’t go straight for an abundance of wood chips because they are the biggest and bulkiest, and the bacteria required to break them down depletes the soil of much-needed nitrogen.
It is best to start in manageable sections and not to try and change the entire garden at once, especially if you have a big garden.
Using liming agents, like calcium and lime
What about acidic, clay soil? Sometimes the soil will also be heavily acidic, which means you may need to further amend it using liming agents. Liming agents, like calcium, forces the particles to clump together instead of packing together and this improves drainage. You will want to use a soil pH kit to test the acidity before you try this method, just to make sure the soil is suitable. You should follow the instructions per packet.
Gypsum is another option, and one that changes the structure without changing the acidity. If you are using this method, you should test smaller areas before you apply to the entire garden.
What if my plants are already growing? That’s okay, if your plants are already established, you can still improve clay soil by adding thick layers of leaf mould and compost over the course of the summer to the surface of the soil. This will improve moisture retention and prevent it from cracking. With this, don’t worry about digging in the mulch because worms and insects will move nutrients down into the soil for you.
- Keep away from the soil when it is wet. If you walk or stand on it, you will only further increase the compaction of the soil.
- Similarly, do not dig or plant when the soil is wet.
- If you can, lay down wooden planks on which to walk so that your weight is evenly spread as you work throughout the garden.
- Dig over the soil in the autumn, and this is when you want to add organic matter.
- Create ridges on the surface, with a rake across the top for example, so that frost in winter can get in and forcibly break apart the clumped soil.
The Best Plants to Grow in Clay Soil
Rest assured there are ample plants that will grow happily in clay soil, as long as you provide them with an appropriate level of sunlight.
If you want trees, there are native British trees like the Elder, Ash and Oak that will do well in clay soil. Birch and Eucalyptus are ideal if you are wanting to grow taller trees for perimeters or borders. If you would prefer to plant fruit trees, apples and pears can be useful. Conifers work too if you invest in Juniper, Pine or Thuja.
Shrubs work well in clary and tend to do better with wet conditions once they are fully established. There are shrubs with berries and evergreen leaves, for example, Cotoneaster, Pyracantha and Mahonias.
Then there are flowering shrubs you have the option of planting, such as, Buddleia, Forsythia and Weigela. Some roses can do well too, if you give them a lot of organic matter and plant them in a sunny location.
Flowering plants work well if they are perennials. Once they establish themselves in the soil, they will provide you with some beautiful floral displays.
- If you have a shady area, fill it with Hostas or Euonymus. If you want some groundcover, try Vinca or Alchemilla mollis.
- If you want flowering perennials, the daisy family has Asters and Coreopsis.
- Woodland plants can also do well, some examples of these are Phlox, Aconites and Japanese Anemone.
- If you need bedding plants for sunny areas, Geraniums, Cranesbill and Pulmonaria are a good choice.
- If you have an area with full sun to partial shade, Astrantia or Solidago are well suited.
- Don’t let the climbers go unnoticed though. You can grow Honeysuckle, clematis, or ivy.
- If you prefer bulbs, you can grow Snowdrops or Narcissi in clay soils.
Plants work well too, particularly the hardy plants that tolerate full sun all the way to partial shade. These include ferns, Japanese Anemones, Hosta, Ajuga and ivy. Other plants, like Hydrangeas or Viburnum, tolerate partial shade.
You can grow vegetables in clay soil too, particularly classic crops that are harvested in the late summer or autumn like squash, pumpkins, onions, cabbages, cauliflower and leeks. Remember though, that while these are tolerant of clay soil, they need ample sunlight.
The Top 10 Plants for Clay Soil
- Alchemilla mollis is a great edging plant. It will give you wispy stems that are frothy from a distance. It produces flowers that are yellowish-green in colour. The plant itself grows very low to the ground and can tolerate partial shade.
- Crab apples trees provide a beautiful spring display, with their rich colours, blossoms and colourful fruit. These are best for larger spaces with good sunlight.
- Bergenia cordifolia is known for its spires of red or pink flowers and its evergreen leaves. They are so beautiful and large that they have earned the plant the nickname ‘Elephant Ears’. They are well-suited for using as groundcover and are tolerant of shade.
- The Spiraea japonica is a shrub with lots of tiny flowers that are grouped in small clusters. It grows well in clay soils, is tolerant of drought and will attract bees and butterflies to your garden.
- The Viburnum tinus produces white flowers that open at the end of winter and give your garden a delightful backdrop in preparation for spring. The growth is dense, compact and very useful for creating an enclosure.
- Syringa vulgaris (or Lilacs as they are more commonly known) are tough but produce quite a glorious display. They flower for a short amount of time, however, during this time you can cut the blooms for displays, and enjoy their rich scent.
- The Rose ‘Roald Dahl’ is a repeat flowering variety, which means you can enjoy 2 flushes minimum each year. This rose tolerates clay soil well and has a very rich scent.
- The Ribes sanguineum is a flowering currant plant that is vigorous and grows quickly. This shrub will establish itself well and eventually reach up to 2 metres in height. However, it gets too big, feel free to prune it after it has finished flowering, once summer arrives.
- Honeysuckle is a scented climber that quickly perfumes an area and is easy to grow up and over any arch, pergola or seating area.
- Pulmonaria is tolerant of shade and is a low growing perennial sure to attract lots of bees to your garden. There produce some lovely blue flowers that do well when grown next to yellow Daffodils.
When to plant
Aim to plant new shrubs, perennials and plants in the spring rather than the autumn. This is so that your plants can establish themselves in dry, warm weather. With woody varieties like trees though, aim for the beginning of autumn.
Last update on 2024-02-05 / Affiliate links / Images from Amazon Product Advertising API