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This green manure mix can be sown between March and October and requires warm soils which aren't waterlogged. For the best results, start by clearing the area of any unwanted vegetation. Then, lightly cultivate the soil with a fork to create a medium tilth (a fine, crumbly texture). Once prepared, scatter the seeds evenly on the surface, rake gently, and water in. Within 5 to 14 days, the first seedlings will appear. Please be aware that crimson clover and white mustard may be preyed upon by slugs and snails so preventative action may be needed if your garden suffers from them. After a few weeks, the seedlings will be large enough to look after themselves.

Growth is typically fastest during the summer months, but early spring or late autumn sowings may take longer to mature. If you sow after September, the plants may not grow large enough to provide significant benefits until the following spring. However, they will still offer essential cover for the soil over the winter months.

When to dig in the mixture depends on your garden's needs. A summer-sown mix generally requires at least 8 weeks to start providing benefits. However, you can leave the plants in the ground as long as desired. If left to flower, the plot will become a buzzing haven for pollinating insects, attracting bees, butterflies, and other beneficial species to your garden.

The species in this mixture have been selected for their ability to provide benefits to the soil in a relatively short space of time. In particular the benefits arise from the plants' role in the nitrogen and carbon cycles. They grow a dense above-ground canopy of fresh, green vegetation in as little as 8 weeks after sowing (during summer months). This luscious green material contains many different nutrients and elements. Some of which have been mobilised and scavenged from the soil by the dense network of roots, these will then be returned to the soil when the mixture is dug in - crucially they will be more accessible to the following crop.

One of the key benefits of this mixture comes from nitrogen fixation. Crimson clover, a nitrogen-fixing plant in the mixture, hosts rhizobium bacteria in the nodules of its roots. These bacteria convert nitrogen from the air into a form that the plant can use for growth. This process increases the available nitrogen in the soil, which is essential for healthy plant development. Unlike non-nitrogen-fixing plants, which only use existing nitrogen in the soil, crimson clover adds a valuable supply of nitrogen once it decomposes or is incorporated into the soil.

Crimson clover also forms symbiotic associations with arbuscular mycorrhizal fungi; a micrscopic but vast network of hyphae. These fungi exchange nutrients with the clover - obtaining some nutrients from the plant’s roots while foraging deeper into the soil to supply the clover with essential nutrients it may otherwise lack. Over 80% of plants form associations with mycorrhiza so keeping a the mycorrhizal population healthy in your garden will benefit future crops.

All plant growth is powered by photosynthesis, a process where plants convert carbon dioxide (CO2) from the air into glucose, oxygen, and other vital compounds. The glucose produced is used for energy and to build essential plant structures, including proteins, starches, and cellulose. This process makes carbon the building block of life—captured by plants and made available to all living organisms in the ecosystem.

After the plant material is worked into the soil, both macroorganisms (like worms and beetles) and microorganisms (such as bacteria and fungi) begin decomposing the biomass. As they break down the plant material, they liberate nitrogen, carbon, and other nutrients, supporting their own growth and contributing to a thriving, diverse soil ecosystem rich in fertility.

If left long enough to produce flowers, all three species in the mixture have the capacity to provide pollen and nectar to pollinating insects.

Phacelia is particularly beneficial to pollinators and is recognised for this by featuring on the RHS Plants for Pollinators list. Learn more at rhs.org.uk/plantsforpollinators.