Optimising Soil Health and Site Preparation
The foundation of successful planting schemes
A thriving landscape starts with healthy soil. As an award-winning supplier of plants to the commercial landscaping industry, we understand that the key to a flourishing garden, or outdoor space, lies beneath the surface. Soil health and site preparation should not be considered as optional extras; they are the foundation of a resilient and long-lasting landscape. In this blog, we’ll delve into the importance of soil health and the essential steps to ensure your soft landscaping yields stunning results.
Understanding soil health
Soil is a complex ecosystem, teeming with life. Healthy soil has a balanced composition of organic matter, minerals, water, air, and living organisms that work together to support plant growth. Ideally soil for planting is usually comprised of 50% organic or inorganic substrate, 25% air space, and 25% water space. When soil health is compromised, plants struggle to access essential nutrients, water retention becomes an issue, and susceptibility to disease increases.
The benefits of healthy soil
- Nutrient availability: fertile soil is rich in nutrients like nitrogen, phosphorus, and potassium that plants need for optimal growth. These nutrients are released and made available to plants through microbial activity.
- Water retention: well-structured soil retains water, ensuring plants have a consistent water supply even during dry spells. This prevents water stress and promotes healthy root systems.
- Root growth: healthy soil allows roots to penetrate easily, establishing a strong foundation for plants to anchor themselves and access nutrients deep within the soil.
- Disease resistance: soil rich in beneficial microorganisms helps suppress harmful pathogens, reducing the risk of plant diseases.
- Aeration: properly aerated soil allows air to reach the roots, promoting vital biological processes and preventing root suffocation.
In total, the UK’s soils store around 130 trillion litres of water – more than all UK lakes and rivers combined!
Creating a soil management plan
On large construction sites, it is worth planning how to protect and store soil on site whilst ground works and building works are taking place. Where possible, remove and stockpile soil during dry conditions and employ machinery with tracks to reduce compaction. Designate routes for traffic to avoid planting areas being compressed.
If the ground has been compacted by building works and heavy machinery, it will not allow water, air, nutrients and plant roots to penetrate and it impedes detritivores, like earth worms, from breaking down organic matter. For large areas, an aerator machine will remove plugs of soil, or simply puncture it, to allow air to penetrate and give the soil space to decompress.
Preparing the soil for planting
The first thing to do when planning an area for planting is a comprehensive soil test. This analysis will indicate the soil’s pH level, nutrient and mineral content as well as presence of contaminants, guiding you on which soil additives may be needed and which kind of plants will thrive.
If the soil is poor quality, it can be improved by adding organic matter such as peat-free compost, well-rotted manure, or soil conditioner. Organic matter enhances the soil’s structure, nutrient content, water retention capabilities and ability to bind to pollutants. Gently till the soil to ensure the organic matter is thoroughly mixed in. Soil conditioners can also be useful for adding minerals to loosen heavy clay soils or increase the pH of highly acidic soils. We recommend the use of Oenosan, a lime-based fertiliser, that balances soil nutrients to support optimal plant growth, improve soil structure and increase soil pH.
If clean topsoil needs to be imported, use a reputable supplier that operates from a sustainable source. It is desirable to have 150mm depth of topsoil for lawns and ornamental grasses, and 400mm for trees and shrubs. Cultivate the soil to remove large lumps and produce a fine tilth that’s suitable for planting – ideally less than 50mm clusters, or less than 10mm if laying turf or seeding. Remove any stones, rubbish or vegetation that is brought to the surface.
Selecting suitable plants
Select plants that are well-suited to the soil type and local conditions. The Greenwood Specification guide is categorised to help you choose plants by soil type and environment – whether it’s acidic or alkaline soil, a coastal garden or an area prone to drought, there is inspiration to help you. It’s always beneficial to include native plants in a planting scheme as they thrive in their natural environment, often require less maintenance and are important for supporting biodiversity.
When preparing to plant, ensure that there is enough space for the plants to mature, both above and below ground. Container grown plants can be planted throughout the year but avoid planting when the soil is frozen or waterlogged or when there is a drought. Bare root and rootball plants should be planted during the dormant season, from November to March.
Planting best practice
Dig a hole that is the same depth as the rootball but twice as wide. Lay a cane across the hole to check where the soil level will sit – it should meet the stem or trunk at the point where the roots flare out. Break up the soil around the hole to allow roots to penetrate.
Water plants thoroughly before planting. Gently remove the plant from its pot and loosen the roots so that they are free to grow into the surrounding soil. Position the plant and back fill with soil. Firm the soil and thoroughly water around the rootball to remove air pockets.
Trees that are being established within hard landscaped surroundings will require a structural soil cell system to prevent soil compaction. The trees will also benefit from tree staking kits, or anchoring systems, to secure them until they are established and can stand unsupported.
Applying a layer of mulch around plants will help to conserve moisture, suppress weeds, provide winter protection and gradually improve soil structure as the mulch breaks down. Mulching also reduces the amount of maintenance required and is aesthetically pleasing. Mulching with organic matter, adding green compost and allowing leaf litter to remain on the soil supports beneficial microbes. These microorganisms enhance a plant’s absorptive area and provide greater resistance to drought, root rot, and nutrient deficiencies. Read more about the importance of soil fungi in our blog.
Make sure to regularly monitor the soil’s moisture levels and adjust watering accordingly. An annual top dressing of general purpose fertiliser can be added to beds before re-applying mulch in future years.
The long-term payoff
Investing time and effort into soil health and planting preparation is an investment in the long-term success of the landscaped area. Focusing on these foundational aspects will result in a sustainable garden that requires less intervention, is more resilient to environmental challenges and has longevity.
The success of a planting scheme comes from understanding and respecting the soil beneath it. By considering soil health we can transform ordinary areas into flourishing green spaces that have a positive effect on peoples’ lives and how they connect with nature.
For more information on the soil improvement products that we supply, including Oenosan, please contact the G Team: