This is the first of a two part blog on biostimulant use in turf. The second part is here.

The public has become more aware of the impact of synthetic fertilisers and chemicals on the environment. The result is many turf managers have begun to use biostimulants for turf management in Australia. At very low rates these have many benefits and give a positive growth response. A good example of this response is the use of the turf pigment Vertmax Duo which contains salicylic acid. This not only filters UV light and gives a rapid colour response but also increases growth and lateral root branching.

Yet, their use should be tempered with the knowledge that if you decide to go down this path you need to know what you are using. Simply, using “a biostimulant” and expecting results is no guarantee of success and is most likely going to be a waste of time and money. For example, many turf fungicides kill the very organisms you are trying to encourage.

Biostimulants for turf are substances or microorganisms that you use on turfgrass to enhance plant growth and health. They improve the overall quality of the turf by increasing its resistance to stress and disease, and by promoting root development. Biostimulants work by stimulating the plant’s natural physiological processes, and they can be used in combination with fertilizers and other products to improve the overall health and appearance of turfgrass.

Examples of biostimulants for turf:

  • Seaweed extracts: These extracts contain a variety of natural compounds that can promote plant growth and health, such as hormones, minerals, and amino acids.
  • Microorganisms: Certain bacteria and fungi can be applied to turfgrass to improve root development, nutrient uptake, and disease resistance.
  • Humic acids: These acids are derived from decomposed organic matter and can improve soil structure and water-holding capacity, as well as increase the availability of nutrients.
  • Plant extracts: Some plant extracts like aloe vera, can be used to improve plant growth and health.

Biostimulants for turf are not regulated by the APVMA. As a result, it is important to research the product and check the label for the active ingredient, the amount, and the specific use before application. Also, consult with a professional before applying any biostimulant, as different turf types may require different biostimulant treatments.

There is a constant stream of new products coming onto the market which make massive claims with little supporting data. This blog is an attempt to cut through the marketing and get to the facts

Humic substances as biostimulants.

Humics are “natural, highly broken down organic substances with very complex structures”. These are either humin, humic, and fulvic acids. Even if two products contain the same amount of humic acid, they may have come from different sources and so give very different responses.

Humic substances:

  • Improve the growth of roots and shoots;
  • Cause an increase in the CEC of a soil;
  • Improve the structure of the soil;
  • Increase the activity of soil microbes;
  • Enhance nutrient uptake and plant hormone activity;
  • Improve seed germination.
The video below shows the growth response with Humifirst®.


Plant hormones as biostimulants.

Stresses such as heat, cold, and drought cause several hormone responses that turf plants use to survive. 5 major plant hormones play a role in turf grass.

  • Indoleacetic acids (IAA). These are also known as auxins and promote root and shoot growth;
  • Gibberellic acids. These promote shoot growth and the germination and growth of seeds;
  • Cytokinins which regulate turf growth and development;
  • Abscisic acids that cause a turf response to environmental factors and
  • Ethylene which causes a growth response.

Of these the most important are cytokinins, gibberellic acid, and abscisic acid. Hormones can either be synergistic or antagonistic. An antagonistic effect is when hormones affect the same part of the plant but work against each other. In contrast, a synergistic effect is when the effect of two or more hormones is greater than the effect of the individual hormone. By knowing what specific hormones do, it is possible to tweak them to get the desired turf response.

  • Vertmax Duo contains salicylic acid which increases turf stress tolerance, speeds up seed germination, and increases root growth and branching;
  • Using strobilurin fungicides and products like Lexicon Intrinsic. This reduces turf respiration meaning more energy goes toward turf growth;
  • The use of trinexapac ethyl (Amigo 120ME) in shade. This increases the production of cytokinin and inhibits gibberellic acid.


Seaweed as a biostimulant for turf.

At low levels, seaweed extracts can cause many beneficial plant responses. Its two main uses in the turf industry are to encourage root growth and to increase stress tolerance. Seaweed products contain organic and mineral compounds. These include:

  • Growth substances like auxins, cytokinins, GA’s, and brassinosteroids;
  • Very low amounts of nutrients;
  • Alginates and
  • Amino acids.
As seaweed products do not all contain the same ingredients they won’t give the same results. The reason for this difference could be due to where the seaweed is from or what process was used in its manufacture.  
The type of cytokinin and turf type has a big effect on the response you get. Responses include:
  • Cell division;
  • Shoot initiation;
  • The growth of lateral buds;
  • Leaf expansion;
  • Increases in the opening of stomata and
  • The production of chlorophyll.

Seaweed on cool season turf.

Studies with cool-season turfgrass show:

  • 67% to 175% more roots compared to untreated plots;
  • 38% more top and 52% more root growth in the spring;
  • Increases in photosynthesis;
  • More leaves and shoots having a higher shoot and root mass;
  • Higher drought and salinity tolerance and
  • If you use seaweed plus iron in the autumn, it helps warm-season turf keep its colour and encourages early spring green-up.

Work in 2013 shows that foliar seaweed extracts result in 15% less root decline over a 42-day heat stress trial. A 30-day interval between applications is fine at first, but as heat and turf metabolism increase, the interval between treatments should be shortened to 14 days. This shorter interval during hot summer weather is because cytokinins etc tend to break down faster in the plant as the temperature increases.

Seaweed used as a bio-stimulant has a number of roles within the plant.


Phylgreen® is a natural extract of Ascophyllum nodosum and it maintains all its “goodies” as a result of its extraction process. By pre-stress conditioning the turf, it conditions turf against abiotic stress. This is called a “Primactive Effect” and increases the ability of turf to cope with stresses such as heat or drought.

Amino acids.

There are 20 amino acids that turf needs for growth and the table below summarises some of these. Like all plants, turf contains several amino acids, which are the building blocks of proteins. When a turf plant grows under ideal conditions it can manufacture all the amino acids it needs. However, in reality, turf grass is seldom grown under ideal conditions and so additional amino acids make up for any shortfall that exists during stress periods. The use of foliar L-amino acids:


Work by Mertz et al on turf shows that the use of amino acids:
  • Improves putting green performance in older low-shoot density creeping bentgrass, without having to re-surface;
  • Increases the evenness of a putting surface during periods of high stress and
  • Helps control turf nematodes.

Delfan Plus V.

Delfan Plus V is an L-α amino acid biostimulant for turf. L-α amino acids are potent plant biostimulants and turf stress relievers. Some of the amino acids in Delfan Plus V are anti-stress compounds which the plant uses to maintain growth.

The key is making Delfan Plus V applications before stress occurs. Delfan Plus V helps to reduce negative stress chemicals and as a result of this the turf is better able to resist abiotic stress.
water drop with and without the addition of the bio-stimulant delfan Plus showing spreading effect.

Delfan® V Plus has also been used as a spray tank additive to reduce the surface tension of turf chemical sprays and increase chemical to target contact.

After adding the bio-stimulant Delfan Plus the surface tension is reduced and full coverage occurs.
Gilba Solutions company brochure

Defan V Technical Sheet

Gilba Solutions company brochure

Research showing the importance of timing when applying bio-stimulants such as Delfan Plus.

Kreotec® as a biostimulant for turf


Kreotec® is an inoculant, that contains a blend of bacteria. After application to the leaf surface these enter through the leaf stomata and live inside the plant. Kreotec® increases nitrogen use efficiency and cuts back on the need to apply fertilizer by adding up to 30 Kg of Nitrogen/Ha.

  • Work on lettuce shows an increase in growth. It reduces fertilizer needs by up to 60% of the normal rate with no yield decreases.
  • In ryegrass there are yield increases.
Kreotec biostimulants in turf on tomatoes gave an increase in leaf area
Bio-stimulants in turf - Kreotec gives an increase in yield with less fertilizer
Kreotec use in Italian ryegrass
Kreotec bio-stimulant use in tomatoes
Kreotec use on wheat improved yields

In the second part of this blog on biostimulants in turf we cover VAM and Trichorderma.


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Senior Turf Agronomist at Gilba Solutions Pty Ltd | 0499975819 | Website | + posts

Graduated from Newcastle University with an Hons Degree in Soil Science in 1988, Jerry then worked for the Sports Turf Research Institute (STRI) as a turf agronomist before emigrating to Australia in 1993.

He followed this by gaining a Grad Dip in Business Management from UTS. He has worked in a number of management roles for companies as diverse as Samsung Australia, Arthur Yates and Paton Fertilizers.

He has always had a strong affinity with the Australian sports turf industry and as a result he established Gilba Solutions as an independent sports turf consultancy in 1993. Jerry has written over 100 articles and two books on a wide range of topics such as Turf Pesticides and Nutrition which have been published in Australia and overseas.