Kelp: Micronutrients with a Motor

For thousands of years, kelp has been harvested and used for food, medicine and yes fertilizer. Since our inception here at Mother Magnolia, we have looked for every conceivable soil additive and amendment that can unlock the potential of soil biology and nurture our plants. We have been devoted to curating the most balanced, bioavailable soil we can through the use of a wide array of inputs. One of the inputs that has been in our arsenal since the beginning is a gift from the ocean. Kelp. What is it and why do we include this miracle input in our regimen here on the farm? Let’s dig in. 

Kelp is most often sourced from Ascophyllum nodosum (North Atlantic variety). We prefer to use a concentrated soluble form of kelp that we drop directly into our reservoir and deploy directly into our fertigation system. And here are the top three reasons why we love using kelp. 

First, kelp has a beautiful array of micronutrients that have been absorbed from the ocean. All of the trace minerals present in kelp provide these micronutrients to the soil web which help to ensure that there aren’t any gaps in what sometimes can be some tricky holes in the soil line up. The one key micro here to highlight is Boron. The real key here is that to move the needle in a meaningful way so that Boron deficiency is not an issue in your soil, you actually don’t need a lot. Boron is typically low in sandy soils or soilless mixes so a small but significant dose of Boron from kelp can eliminate this issue altogether. 

Secondly, kelp is a serious biostimulant. In 2015, when we were first developing our SOPs around commercial scale cultivation, I wanted to lean on three main biostimulants in our production: Kelp, humics and fish hydrolysate. What are biostimulants? Put simply, they are inputs or compounds that stimulate or improve a plant’s ability to uptake nutrients or mitigate a plant’s stress response. It can work in conjunction with the microbiology or it can work directly on the plant. 

So how is Kelp a biostimulant? Kelp has a nice dose of plant growth regulators known as phytohormones—auxins and cytokines. These compounds promote cell division and stimulate root growth. They also help support plant stress such as salinity, temperature and swings in moisture levels. Kelp works in synergy within the soil web and stimulates plant growth with a broad spectrum of those phytohormones. 

The third key role that kelp plays is as a primary source of Potassium (K). The NPK levels in kelp are essentially devoid of the first two—nitrogen and Phosphorus—but there is a very stout dose of potassium in kelp. K in plant growth is a key transport element that helps control stomata opening and closing which improves water-use efficiency. Further, K is a key nutrient for enzyme activation. Enzymes are essential for so many metabolic needs in plant growth and development. And finally potassium is a key shuttle nutrient that pulls nutrients into the plants cells and supports plant growth at the cellular level.  

So what is the best version of kelp to use? There are really two options: kelp meal and soluble kelp. Soluble kelp is much more concentrated than kelp meal. During the last ten years we have primarily used kelp meal as a top dress or as an additive to compost teas. When we really want to deploy a more concentrated form of kelp into the garden, we reach for soluble kelp. Kelp meal is a slow release form of kelp that you can top dress on beds. It feeds the soil microbes and provides a nice pop of carbohydrates to the soil. In contrast, soluble kelp is water-soluble and is meant to be a more readily absorbable form of kelp that is deployed in fertigation systems. This more concentrated form of kelp is our go-to for a rapid boost to plant growth. 

Whatever it is that your cultivating, consider including kelp into your line up. It is an ancient input that has been used for thousands of years. And if you want a product that is all-in-one, consider looking at Flowerbird plant food. It is a nice blend of Humics, Kelp and Fish Hydrolysate. It’s in the store right here on the site. Give it a shot, your plants will thank you.