Seaweed on Almonds


The Importance of Potassium (K) in Almonds

Potassium is major nutrient for almonds. It is involved in enzyme activation, photosynthesis, sugar translocation, protein synthesis, starch synthesis, and stomatal function. Approximately 76 pounds of potassium are removed per 1,000 pounds of kernel harvested. Nearly 70% of the harvested potassium is accumulated in almonds by mid-June. Potassium deficiencies can occur if potassium is not replaced and leaf potassium falls below 1% K. Potassium replacement should be initiated after harvest and continue through flowering in the following season. Traditionally potassium chloride, potassium sulfate, potassium thiosulfate, potassium nitrate, potassium carbonate, or potassium magnesium sulfate are used to replace removed potassium. Organic sources of potassium include greensand, langbeinite, manure, compost, potassium sulfate, mined rock powders, seaweed, sylvinite, and wood ash. There are some restrictions, as products may not undergo further processing or purification after mining or evaporation other than crushing or sieving. In California, approximately 50% of the typical potassium fertilizers are applied to almonds in May and June and 50% after Harvest (3).

What is Seaweed?

Seaweed was first used as early as 2700 BC in China, mainly as a food for special guests or kings. In Europe, Mediterranean seaweeds were used as medicine or animal feed around 100 BC. Circa 1200 AD, seaweed found uses in agriculture as mulch. In the 1950s, development of a process to liquefy seaweed revolutionized the widespread use of seaweed in agriculture. Currently seaweed products are produced by alkaline or acid hydrolysis, cellular disruption under pressure, or by fermentation.

Seaweeds are macroscopic marine algae that inhabit coastal regions of the world’s oceans. They are organized into three main groups based on their pigmentation: 1) Phaeophyta - brown algae; 2) Rhodophyta - red algae; and 3) Chlorophyta - green algae. The brown algae are the second most abundant group and are the type most commonly used in agriculture. Within this group, Ascophyllum nodosum, Fucus spp., Laminaria spp., Sargassum spp., and Turbinaria spp., are used as bio fertilizers. Let’s take a quick look on what seaweed can do for your crops.

Seaweed has Plant Growth Regulators, Nutrients and Vitamins.

Seaweed has many other useful components in addition to potassium. It contains a variety of macro- and micronutrients, amino acids, cytokinins, vitamins, abscisic acid like compounds that can result in enhanced growth and yield (2). Prior studies in a variety of plants have shown several plant responses that would be particularly useful to almonds.

Seaweed has beneficial effects on germination and early plant growth and establishment. Foliar sprays increased plant length, stem diameter, primary branches, number of branches, leaf area, leaf chlorophyll content, and root growth in almond seedlings (1). Thus it is expected that seaweed use would produce results on almonds that are similar to those observed on other plants. These would include improved tolerance to abiotic stress such as drought and cold tolerance, improved plant growth and health, increased yields.

Recommended use of Seaweed on Almonds

In addition to your standard crop management practice, there are a few suggestions to make the best use of seaweed’s plant growth enhancing abilities. Since almonds are heavy potassium users, the additional potassium in seaweed is an additional benefit. One application use of seaweed is as a root dip (one pound Soluble Seaweed dissolved in 100 gallons of water) immediately before planting, followed with foliar sprays (1-3 pounds per acre) at three to four week intervals to promote early root and foliar growth. For established orchards, make applications in May through June, and post-harvest. The added benefits from the other components in seaweed make it particularly useful during stress periods of almonds. 

Crop Growth Stage

Pink Bud

Bud Burst


Leaf Growth

Nut Growth - Hardening to Split




Root Growth




Nut Growth


Bud Development


Crop Stress Points


Cold Temperature Sensitive





Energy for Bud Development






Heat Stress Effects Floral Bud Development






Water Stress



Water Stress


Kelp recommendation (Soluble Seaweed)

Use as part of an overall nutrient management program.

Foliar spray 1-3 pounds per acre at:

  1. Pink bud.
  2. Petal fall.
  3. Before summer heat stress (May to early June).

Foliar spray every 2-4 weeks during summer months.

Foliar spray 1-3 pounds per acre 2-4 weeks after harvest.



  1. Abdulrahman, A. S. 2013. Effect of foliar spray of ascorbic acid, zinc, seaweed extracts and biofertilizer (EM1) on growth of almonds (Prunus amygdalus) seedling. International Journal of Pure and Applied Sciences and Technology 17 (2):62-71.
  2. Khan, W., Rayirath, U. P., Subramanian, S., Jithesh, M. N., Rayorath, P., Hodges, D. M., Critchley, A. T., Craigie, J. S., Norrie, J., and Prithiviraj, B. 2009. Seaweed extracts as biostimulants of plant growth and development. J. Plant Growth Regul. 28:386-399.
  3. Fruit and nut Information, University of California David Doll, et al., UCCE Farm advisor, Merced County.
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