Biostimulants

Biostimulants are not fertilisers; instead, they can improve plant growth and crop yield by activating or boosting naturally occurring processes. Think of biostimulants like vitamin tablets – while they don’t have a nutritional value, they do help maintain and enhance plants’ normal functioning alongside food.  

Biostimulants are an optional add-on, not a substitute for good soil care practices and right plant, right place selection. Where optimal growing conditions already exist, they’re unlikely to improve plant performance.

Each differs in the way they work, and the benefits they offer. 

• Amino acid biostimulants boost protein synthesis, improving the uptake of nutrients
  To grow well, plants need a wide range of nutrients in various amounts, depending on the individual plant and its stage of growth. The three key nutrients usually taken up from the soil are nitrogen, phosphorus and potassium. Plants also need carbon, oxygen and hydrogen to make carbohydrates — their main energy source. Carbon and oxygen come from the air as carbon dioxide, while hydrogen is drawn from water absorbed by the roots. Other important soil nutrients include magnesium, calcium and sulphur. Most garden soils contain enough of these nutrients to support healthy plant growth. already present in the soil or growing medium
• Microbial biostimulants contain organisms, such as fungi. These form beneficial associations with plant roots, supporting uptake of water and nutrients beyond the root zone
• Anti-transpirant biostimulants close leaf structures called stomata
  Small pores on the surface of leaves that allow for gas exchange, including the intake of carbon dioxide for photosynthesis and the release of oxygen and water vapour. to help plants retain and regulate water loss

Different biostimulants are sometimes combined to achieve greater effect.

Biostimulants can help plants:

• Improve overall plant quality and yield
• Make better use of the absorbed nutrients
• Take up nutrients
  To grow well, plants need a wide range of nutrients in various amounts, depending on the individual plant and its stage of growth. The three key nutrients usually taken up from the soil are nitrogen, phosphorus and potassium. Plants also need carbon, oxygen and hydrogen to make carbohydrates — their main energy source. Carbon and oxygen come from the air as carbon dioxide, while hydrogen is drawn from water absorbed by the roots. Other important soil nutrients include magnesium, calcium and sulphur. Most garden soils contain enough of these nutrients to support healthy plant growth. more efficiently from soil or potting compost
  Can refer to either home-made garden compost or seed/potting compost: • Garden compost is a soil improver made from decomposed plant waste, usually in a compost bin or heap. It is added to soil to improve its fertility, structure and water-holding capacity. Seed or potting composts are used for growing seedlings or plants in containers - a wide range of commercially produced peat-free composts are available, made from a mix of various ingredients, such as loam, composted bark, coir and sand, although you can mix your own.
• Cope with environmental stress (drought, salinity, temperature extremes)

They offer a potentially sustainable way to garden by enhancing natural plant processes that reduce the need for fertiliser and water. However, some products have additional environmental impacts due to the way they are manufactured. 

It depends on the product, but typically:

• Foliar spray – apply directly to leaves
• Root drench – mix with water and apply to soil
• Root application – dust roots with the product prior to planting
• Seed treatment – soak seeds before sowing

Always follow the manufacturer’s label instructions for dilution, quantity and timing.

1. Seaweed Extracts

• Derived from ‘brown seaweed’ rich in minerals, plant hormones
  Chemical substances that regulate plant growth and development. There are several types of plant hormones, including auxins, cytokinins, gibberellins, abscisic acid and ethylene. These hormones play important roles in processes such as cell division, elongation and differentiation, as well as in responses to environmental stimuli such as light and gravity. and bioactive compounds
• Benefits: Improves root growth, environmental stress tolerance and overall plant vigour
• Common form: Liquid concentrate for foliar spray or soil drench

Included in products such as: Maxicrop, Seaweed Meal/Pellets, Vitax Liquid Seaweed and Westland Seaweed Enhanced Growth Stimulant.  

2. Amino Acids

• Derived from plant or animal proteins
• Benefits: Supports protein synthesis, stress resilience and nutrient uptake
• Common form: Liquid supplements for foliar application

Included in products such as: Empathy After Plant All Purpose, Empathy Evergreen, Empathy Grow Your Own and Empathy Ericaceous.

3. Microbial Biostimulants

• Include beneficial bacteria (e.g. Bacillus subtilis) and fungi (e.g. mycorrhizal fungi)
• Benefits: Improves nutrient uptake, root health and soil biodiversity
  The variety of living organisms (plants, animals, fungi and microorganisms) in a particular environment. Boosting the biodiversity of your garden has many benefits, including supporting wildlife, improving soil health and reducing the likelihood of pest and disease problems.
• Common form: Granules or liquid inoculants for soil or compost
  Can refer to either home-made garden compost or seed/potting compost: • Garden compost is a soil improver made from decomposed plant waste, usually in a compost bin or heap. It is added to soil to improve its fertility, structure and water-holding capacity. Seed or potting composts are used for growing seedlings or plants in containers - a wide range of commercially produced peat-free composts are available, made from a mix of various ingredients, such as loam, composted bark, coir and sand, although you can mix your own.

Included in products such as: Empathy After Plant Rose Food, Empathy After Plant Tree and Shrub, Empathy Rootgrow and Envii Foundation.

A range of products containing mycorrhizal fungi are sold in many garden centres

 4. Humic and Fulvic Acids

• Extracted from organic matter such as leonardite
• Benefits: Enhances soil structure, nutrient availability and water retention
• Common form: Powder or liquid soil improver

Will I notice a difference?

You will often notice a difference – biostimulants are especially helpful when plants face challenging growing conditions. Though plants may look like those grown with nutrient‑rich organic mulches, biostimulants can improve their resilience to drought, support better nutrient uptake and boost crop yields.  

They can also reduce the need for additional feeding because they help plants absorb and use nutrients

To grow well, plants need a wide range of nutrients in various amounts, depending on the individual plant and its stage of growth. The three key nutrients usually taken up from the soil are nitrogen, phosphorus and potassium. Plants also need carbon, oxygen and hydrogen to make carbohydrates — their main energy source. Carbon and oxygen come from the air as carbon dioxide, while hydrogen is drawn from water absorbed by the roots. Other important soil nutrients include magnesium, calcium and sulphur. Most garden soils contain enough of these nutrients to support healthy plant growth. more efficiently. This makes them a more sustainable option compared to traditional feeds.

Can I stop feeding plants?

No – biostimulants work in combination with feeding. Therefore, it’s still important to support hungry plants like vegetables and fruit by mulching

Mulch is a layer of material, at least 5cm (2in) thick, applied to the soil surface in late autumn to late winter (Nov-Feb). It is used to provide frost protection, improve plant growth by adding nutrients or increasing organic matter content, reducing water loss from the soil, for decorative purposes and suppressing weeds. Examples include well-rotted garden compost and manure, chipped bark, gravel, grit and slate chippings. with organic matter. This provides the nutrients that biostimulants need to work effectively. Some biostimulant products have nutrients added in the form of fertilisers. 

Mycorrhizal products are the exception. These work best without additional fertilisers, since this discourages roots from forming fungal associations.

Will biostimulants treat nutrient deficiencies?

No – they help plants access nutrients but cannot supply them where soils or composts are deficient. However, some products are combined with fertilisers that may help to remedy deficiencies.    

Do they work in containers?

Yes – biostimulants can help support plants in containers, provided they are fed adequately.