Leaves clawing downwards, burnt tips and margins, necrotic spots, interveinal chlorosis and stunted growth—it only takes a ten-minute tour of social media these days to discover ample evidence of struggling indoor gardeners. Despite having often invested in the latest and greatest LED grow lights, these indoor growers’ plants look distinctly nonplussed, stressed and unhappy.
Crispy burnt leaf tips and lacklustre flowers are sad sights for any plant lover, but what really pains us is when the accompanying captions suggest the grower is unaware of their problems.
More experienced indoor growers, especially those transitioning from High-Pressure Sodium (HPS) to Light Emitting Diodes (LEDs), tend to be more adept at spotting various forms of plant distress. However, the common advice dispensed on social media platforms (i.e. adding more calmag) isn’t always the most helpful course of remedial action, especially if high root zone salinity levels are the culprit.
The shift from HPS to high-intensity horticultural LEDs often requires adjusting environmental parameters to compensate for the reduced radiant heat. While many LED growers attempt to make up for the reduced NIR from their LEDs by raising daytime air temperatures (typically LED growers cultivating warm-season plants shoot for 28–29°C rather than 25-26°C for HPS), this can lead to warmer nutrient solutions, quicker substrate drying, saltier root zones and unwanted stem elongation.
Combating Plant Stress from LED Grow Lights with Seaweed Extracts
Ascophyllum nodosum-based seaweed extracts serve as a vital resource for those growing plants indoors under LED lighting. These extracts are packed with natural elements such as phytohormones, polysaccharides, and betaines, providing a traditional approach to reduce plant stress, while simultaneously fostering growth, enhancing stress resilience and improving nutrient absorption. For generations, the capacity of seaweed extract-based bio-stimulants to bolster root and shoot growth, elevate yields and strengthen resistance to environmental adversities like dry conditions, salt stress and temperature extremes has been recognised by experienced gardeners. Indoor farmers using intense LED lighting should consider integrating these extracts into their growing practices.
The shift from HPS to high-intensity horticultural LEDs often requires adjusting environmental parameters to compensate for the reduced radiant heat.
Understanding the Mechanism Behind Seaweed Extracts
Seaweed extracts contain bio-stimulants that initiate and amplify plant defence mechanisms through a process known as elicitor-induced resistance. The active components in Ascophyllum nodosum act as analogs to stress signals in plants, sparking a defensive reaction. This process essentially trains the plants, equipping them for the rigorous demands of high-yield indoor cultivation. This natural initiation of stress responses in plants leads to an enhanced production of antioxidant enzymes and defensive compounds such as phenolics and flavonoids, which neutralise damaging free radicals and fortify cell walls. Furthermore, these extracts trigger the synthesis of crucial signalling compounds like salicylic acid, jasmonic acid and ethylene, essential for pathogen resistance and stress management, thereby preparing plants to withstand environmental challenges. The outcome is more resilient plants that are well-suited to handle the rigours of intense LED lighting and elevated temperatures within grow spaces.
Key Benefits of Seaweed Extracts:
- Stress Response Activation: Natural elicitors in seaweed extracts simulate plant stress hormones, leading to an activation of the plants’ defensive systems. This priming allows plants to better anticipate and manage stress factors such as the bright intensity of LED lights.
- Improved Nutrient Absorption and Utilisation: Seaweed’s complex sugars, like alginates and carrageenans, enhance soil texture and boost nutrient accessibility, facilitating a more efficient uptake and utilisation of essential nutrients, which contributes to healthier and more dynamic plant growth.
- Growth Hormone Stimulation: Abundant in cytokinins, auxins and gibberellins, seaweed extracts promote cellular division and expansion, resulting in a more substantial root foundation and stronger plants.
- Antioxidant System Enhancement: Seaweed-derived compounds strengthen the plant’s antioxidant mechanism, allowing it to counteract damaging free radicals induced by stress, thereby minimising cellular harm and promoting ongoing vigorous growth.
- Improved Water Retention: By increasing the plant’s water-holding capacity, seaweed extracts mitigate the potential dehydration under bright LED lights and arid conditions, ensuring plants remain adequately hydrated.
| The Science on Seaweed Extracts (Ascophyllum nodosum) |
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| Ascophyllum nodosum derived bio-stimulants enhanced fruit darkness and improved internal quality, notably in plastid pigments and tocopherols. (T Zamljen, H Šircelj, R Veberič, M Hudina, A Slatnar, Foods.) |
| Ascophyllum nodosum-based bio-stimulants can significantly improve plant growth, stress tolerance, and disease management in agriculture. They promote plant growth and enhance tolerance to abiotic and biotic stresses by improving nutrient use efficiency and plant defence responses. (Shukla et al., 2019, Frontiers in Plant Science.) |
| Ascophyllum nodosum extracts exhibit antioxidant, anti-inflammatory, and anti-senescence activities, which could be beneficial in topical therapeutic applications against aging, suggesting their broader benefits beyond plant health. (Dutot et al., 2012, Applied Biochemistry and Biotechnology.) |
| Research has demonstrated that the extract from Ascophyllum nodosum seaweed can bolster soybean resilience against water scarcity, showcasing its crucial role in boosting plants’ drought resistance. (Martynenko et al., 2016, Biomedical and Life Sciences.) |
| The ability of Ascophyllum nodosum to activate amylase activity in barley without gibberellic acid points to a unique way this natural biostimulant could be promoting early plant growth and seed vitality. (Rayorath et al., 2008, Journal of Plant Growth Regulation.) |
| The use of Ascophyllum nodosum-based biostimulants has been found to increase heat stress resistance during the development of tomato fruits, highlighting its promising impact on enhancing agricultural yields under conditions of thermal stress (Carmody et al., 2020, Plant Science.) |
| Additionally, extracts from Ascophyllum nodosum have been shown to improve both the quality and the secondary metabolic processes in grapevines, underscoring its value in boosting the quality of wine grapes and aiding vines in stress management. (Salvi et al., 2019, Plant Physiology and Biochemistry.) |
The Best Seaweed Extract for Indoor Growers (Organics, Coco Coir, Hydroponics)
flourish is our new 100% natural and organic-approved biostimulant based on the prized seaweed species, Ascophyllum nodosum. Crafted from the purest bioactive compounds and phytohormones derived from sustainably-harvested seaweed, flourish is a superior seaweed extract thanks to a cutting-edge, low temperature / high pressure extraction process that preserves the highest quantities of bioactive compounds. This results in a highly effective seaweed extract for combating plant stress and maximising growth and bloom potential.
Unlike many general-purpose seaweed extract products, flourish also goes through an advanced filtration process that massively reduces residual organic matter in the extract, making it suitable for use in hydroponic reservoirs. This is big news for hydroponic growers, unlocking the power of seaweed extracts for a wider range of cultivation methods, from living soil beds to active hydroponics systems. flourish remains stable in hydroponic nutrient reservoirs for the entire working lifetime of the solution and won’t leave dark stains on leaves when used as a foliar spray.
Growers will fully realise the potential of seaweed extracts when they’re used across the whole plant life-cycle. flourish will not only enhance germination rates and rooting success of stem cuttings, but also boost vegetative vigour and promote stunning flower development with enhanced terpenes and secondary metabolites. As roots begin to crowd their containers during peak flowering, the water holding capacity of the substrate is reduced leading to an increased risk of drought stress and salt build-up. flourish really comes into its own during this challenging time, helping to keep your plants focused on thriving, rather than just surviving.
Sustainably sourced and manufactured in the United Kingdom, flourish is approved for use in organic cultivation by the Soil Association and, as such, can be easily incorporated into organic or mineral-based feed solutions. As mentioned earlier, flourish can also be used as part of a foliar spray, making it versatile and effective throughout the entire plant life-cycle. We believe that cultivators transitioning to or using LED grow lights have lots to gain by incorporating flourish into their nutrient regimen. The increased resilience in growth, elevated stress tolerance, and improved overall plant health all add up to bigger harvests and higher crop quality.
Ready to see what flourish can do for your plants?
Visit your local indoor gardening retailer or read more about flourish here.
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