Seaweed Biostimulants: What They Are, What They Do and Which One to Choose
Quick answer: a seaweed biostimulant is a liquid extract from brown algae (such as Ascophyllum nodosum, Laminaria or Ecklonia maxima) that supplies natural phytohormones, polysaccharides and easily absorbed micronutrients. It's used to support the crop during periods of highest demand (rooting, flowering and fruit set) and to help it recover from heat, cold or drought stress. It's applied through fertigation or as a foliar spray.
What do seaweeds provide to plants?
Seaweed extracts aren't a conventional NPK fertilizer: their value lies in the bioactive compounds they naturally contain.
Alginic acid: a polysaccharide that improves water retention and soil structure, and helps keep nutrients available.
Mannitol and other sugars: act as an energy source and help chelate micronutrients so the plant can absorb them better.
Natural phytohormones: present in brown algae, they play a role in rooting, cell division and flower and fruit development.
Micronutrients, vitamins and amino acids: in small amounts, but highly absorbable.
Seaweed extract with natural phytohormones and micronutrients
Stress and periods of high demand (rooting, flowering, fruit set)
Check with our technical team
Seaweed is also part of combined products: Trasplante Vital (amino acids, seaweed and phosphorus for post-transplant start-up) and Esencia Premium (amino acids with microelements bound to seaweed for flowering and fruit set).
When should you apply a seaweed biostimulant?
Transplanting and rooting: so roots establish faster.
Pre-flowering and flowering: to improve flower quality and fruit set.
Fruit set and bulking: when the plant needs extra energy.
After stress: heat spikes, frost, drought, hail or phytotoxicity.
How to choose between Ondara, Ondara Maxima and Marina?
If you're looking for continuous support from the start of the crop cycle through bulking, choose Ondara Maxima.
If you need to overcome periods of stress or improve micronutrient uptake, Ondara is the most balanced option.
For a general-purpose seaweed extract, choose Marina.
All are available in 5 L and 20 L jugs, and a 1,000 L IBC container for large operations.
Frequently asked questions
Can seaweed be mixed with other fertilizers?
Generally yes, with most fertilizers and biostimulants. Even so, we recommend doing a small-scale mixing test before preparing the full tank, and checking the technical data sheet.
Does seaweed replace base fertilization?
No. Seaweed biostimulants complement your fertilization plan: they improve nutrient uptake and stress response, but on their own they don't cover nitrogen, phosphorus and potassium requirements.
Is it better to apply it as a foliar spray or through irrigation?
Foliar application gives a faster response (ideal for a specific stress episode); fertigation also acts on the root and soil. Many growers combine both throughout the cycle.
What's the difference between Ascophyllum nodosum and Ecklonia maxima?
These are two brown algae species with different profiles. Ascophyllum nodosum is mainly associated with stress resistance and micronutrient uptake; Ecklonia maxima is typically used to stimulate rooting and early development.
Questions about dosage or compatibility? Request the technical data sheet from our team and we'll advise you with no obligation. Also check out our fertilization plan by crop stage.
