The benefits of the use of kelp in horticulture has been known for a very long time. In addition to fish, the Native Americans taught the Pilgrims to till kelp into the soil for better crop growth.
A few decades ago, when kelp products were first offered to the grower, very little was known of their modes of action and many claims were made, some unjustified as well as based on incorrect assumptions. One clear finding was that when applied at specific times and in specific ways, some products triggered physiological responses in crops.
Back then, kelp products suffered from a poor reputation due to their inconsistency and confusing claims. As the decades passed new products were developed and greater science was applied to unlocking the truth behind their applications.
It is now known that the effects of kelp products can be explained by the presence of groups of plant hormones, namely auxins, cytokinins, and gibberellins. Some will tell you of the theory of the “illicitor effect” in which the kelp application triggers responses on a cellular level, for example stimulating enzyme production or certain defense mechanisms. It is now known that not only is the mere presence of these hormones important, but also that differences in the ratios of the various groups will affect the response. For example, a product with a high auxin content and a high cytokinin content might cause an auxin-like response in one crop but cytokinin response in another. If on the other hand the ratio of auxin to cytokinin is high – even if their overall levels are low – an auxin-like response will be triggered in almost all plants.
Seaweed-based products are quite variable, depending upon the species of kelp used, how they are harvested, and how the active ingredients are extracted from them. Among all kelps, as many as eight natural auxins and 16 natural cytokinins have been identified. Gibberellins are also often present, but are quite unstable, so in the processing of most kelp products, they degrade rapidly and are lost. KelpMax is a notable exception.
Structurally, kelp is made up of very tough cell walls that are resistant to rupture. In order to achieve breakdown of the cells to collect their contents most manufacturers use chemical or heat digestive processes, which leads to rapid degradation of the auxins, resulting in commercial products high in cytokinins. Our kelp concentrate, on the other hand, is produced using a patented high pressure differential technique that results in cellular burst, avoiding the use of chemicals, heat, freezing, or dehydration. That ensures extended hormone stability and a product high in auxins. In fact, if kept tightly sealed between uses, cool, and out of sunlight, the product will be usable for at least two years, which is considerably greater than liquid synthetic hormone products on the market.
So how does it work? Simply, this auxin-dominated extract stimulates prolific adventitious, and branching root formation. That drastic increase in root tip growth leads to an increased level of cytokinins in the treated plants, as that group of hormones is primarily produced in root tips. The increased root volume and number of root tips also increases moisture and nutrient uptake. The improve nutrient status, together with the higher levels of natural, internally-produced cytokinins in the plant, gives stronger top growth, making the plant more resistant to stresses such as drought, waterlogging, nutrient deficiency, or salinity, and some soil borne diseases. (There is a more-detailed explanation below, if you’re interested._
Seaweed extracts that are higher in cytokinins will also stimulate plant growth, but primarily in the top growth and not roots, so may lead to plants whose root systems are not developed enough to adequately support them. The result is a bigger, faster-growing plant, but one that can be weaker, and more susceptible to any number of stresses.
If this description isn’t sufficient for you, how about a picture? In the spring, as temperatures warm, we typically see our vandaceous plants begin to sprout new roots, extend existing ones, and then put on a flush of new foliage. Since the addition of KelpMax to our regular fertilizing regimen, we have seen an amazing amount of branching of the roots of all genera.
OK. Now more of the science behind this.
Many of the internal biological processes of plants – just like us – are controlled by hormones. Two of the more important classes of those are auxins and cytokinins. Both play an ongoing role, but let’s start with auxins…
Auxins are naturally produced at the apical meristem of a plant, that is, the “growth tip”. Those auxins flow down into the plant, where they play a role in:
- root elongation
- promoting the formation of more lateral (branching) roots, and root hairs as applicable
- enlarging the thickness and length of roots
- increasing the uptake area and uptake activity of the roots
- increasing the number of root tips
- cambium activity – increasing segment thickness and the creation of more vascular bundles, allowing easier transfer of nutrients and fuels throughout the plant.
- leaf expansion, and the angle at which they are held
- differentiation of vascular tissue – enhances movement of chemicals on-board
- stem cell elongation
It is that expansion of the root system that is of most interest, as it is the newly-growing root tips that produce cytokinins, and as they travel upward through the plant:
- they induce cell division and elongation
- increase of nitrate reductase vitality promoting nitrogen uptake
- slow leaf senescence
- affects the emergence of lateral bud and flower development
- enlarges leaf area
- play a role in the osmotic pressure in roots, thereby promoting greater water uptake and transport throughout the plant.
- induction of cell division and growing tips promotes younger shoots to grow big and strong more quickly
That last item, the stimulation of the shoot growth tips, in turn releases more auxins, and the process recycles. Each phase starts slow, builds to a peak, then begins to fade, like a series of overlapping bell curves. The image below is a simplified representation; in reality the cycling would be better represented by a multitude of closely-overlapping, but diminishing curves over the time period. In most plants, a complete cycle takes about 14-21 days, which explains the recommendation to only “boost” the plants every three weeks or so. As there have been no truly scientific studies on the use of KelpMax with orchids, we recommend applying it monthly, to stay outside of a prior “excitement window”.
By the use of high-auxin kelp extracts, we “cut into” that natural cycle, pushing the plant into a “higher gear” if you will, accelerating all of those processes, giving us healthier, faster growing plants. I was very skeptical of their efficacy, but the reports of others, coupled with my own observations, have me completely “sold”.
Below is a typical analysis of KelpMax™, showing the wide array of stimulants and nutrients available in the formula:
|Growth Stimulants (mg/L)|
|Amino Acids (mg/L)|
|Growth Regulators (pg/L)|