Fertiliser
All Purpose Fertiliser 4-4-4
True all-purpose 4-4-4 for veg, fruit, flowers and containers.
from £12.00
Customer highlight
Great product our plants are thriving with lots of flowers. Anyone who uses seaweed fertiliser would appreciate this.
Editorial highlight from marketplace and store reviews — separate from the full review list below.
Liquid Seaweed Brix+: concentrated Ascophyllum biostimulant for sweeter fruit and tougher plants
Liquid Seaweed Brix+ is a concentrated Ascophyllum seaweed biostimulant that carries triacontanol alongside cytokinins, gibberellins, auxins, betaines and mannitol. Used little and often as a foliar spray or root drench, it works on the plant's own growth signalling: more photosynthesis, more sugar in the sap and a buffer before frost, drought or heat. It is not a feed, so it goes alongside your usual fertiliser.
- Sweeter, fuller-flavoured fruit. Seaweed products raised soluble sugar in fruit by about 18% across 73 field studies.
- More photosynthesis. Triacontanol is active at tiny doses and lifts the leaf's capacity to make sugar.
- Faster recovery from stress. Spray before a forecast frost, drought or heatwave, or after transplanting.
- Steadier roots. A monthly drench supports root establishment and soil biology.
- Very concentrated. At 2–2.5 ml per litre, 1 litre makes 400–500 litres of spray.
Ascophyllum nodosum
Triacontanol + natural growth compounds
N 0.26%, K 1.65%
Foliar and drench
Vegan
Use within 6 months of opening
Part of our seaweed fertiliser range. For every seaweed format compared, read our seaweed fertiliser guide.
What's in Liquid Seaweed Brix+
Ascophyllum nodosum extract
Cold-water kelp carrying cytokinins, auxins, gibberellins, betaines and mannitol.
Triacontanol
The lead compound, a natural plant growth regulator first identified in alfalfa.
Kelp trace minerals
A declared spread of ocean trace elements.
| Component | Value | Note |
|---|---|---|
| Natural acids, phenolics, amino acids, a wide range of ocean trace elements, cytokinins, gibberellins, auxins, betaines, mannitol | 17.5% | Declared as one combined figure |
| Total nitrogen (N) | 0.26% | Trace; not a nitrogen feed |
| Total potassium (K) | 1.65% | |
| Sulphur (S) | 0.37% | |
| Magnesium (Mg) | 0.15% | |
| pH | 5.0–5.8 | Mildly acidic; jar test before tank mixing |
| Conductivity | 30–50 mS/cm | Concentrate; falls to negligible at 2.5 ml/L |
| Specific gravity | 1.0 | 1 ml weighs 1 g, so ml and g are interchangeable |
| Appearance | Brown liquid | Can mark pale fruit if sprayed near harvest |
How to use Liquid Seaweed Brix+: foliar spray, soil drench and solution feeding rates
Measuring
Specific gravity is 1.0, so 1 ml is 1 g. Half a 5 ml medicine spoon is 2.5 ml, the top of the foliar range for a litre; a 5 litre sprayer takes 10 to 12.5 ml.
Little and often
Brix+ is designed to be used at low concentration and high frequency. It is preferable to increase the frequency of applications and keep the solution at the same concentration. The growth promoters work through signalling pathways that respond to repeated, regular stimulation. Stick to the dilution rates below and apply regularly through the growing season.
Application rates
Foliar spray: all plants
Shake well before use. Mix 2–2.5 ml of Brix+ per litre of water and apply as a fine spray to both upper and lower leaf surfaces, in early morning or late evening when stomata are open and evaporation is low. Foliar is the quickest route in. Suitable for all plants including lawns, shrubs, roses, tomatoes, vegetables and fruit.
Soil drench: all plants
Mix 5–12.5 ml of Brix+ per litre of water and apply around the root zone with a watering can. The organic acids and phenolics feed rhizosphere microbial activity while the trace minerals and growth promoters are taken up by the roots; a drench gives a longer-lasting, deeper effect than a spray. Use the lower rate (5 ml/L) for regular maintenance and the higher rate (12.5 ml/L) for plants under stress or during peak fruiting demand.
Solution feeding / fertigation: adding Brix+ to a liquid feed
For growers running a two-part liquid feed, add Brix+ to the Part B solution before combining with Part A, or add it directly to the final working solution at 16 ml per 10 litres (1.6 ml/L). The Part B rate assumes roughly 50× dilution into the final reservoir, so do not put 0.4 L per 5 L into the finished tank. Do not pre-mix with concentrated feeds; always dilute into the working volume. The growth promoters and trace minerals supply the biostimulant and micronutrient side that synthetic liquid feeds usually lack.
Stress recovery: before and after frost, drought or heat
Spray at the standard foliar rate immediately before a forecast frost, drought or heat event to prime the betaine and mannitol osmoprotection. If the event has already happened, spray as soon as conditions allow to support recovery: cytokinins delay senescence in damaged tissue, betaines steady the remaining cell membranes and triacontanol restarts photosynthesis.
Growth stage guide
- At planting or transplanting. Apply as a soil drench at 5 ml/L when moving plants into their final position. The auxin signal and trace minerals support root establishment. Dust mycorrhizal fungi powder onto the root ball at the same time for root colonisation.
- Vegetative growth. Begin foliar spraying at 2–2.5 ml/L every 10–14 days. Cytokinins drive cell division and branching, triacontanol lifts photosynthesis, and the plant builds the leaf canopy and root system that will carry the fruit later.
- Pre-flower. Continue foliar applications. The gibberellin signal supports the shift from vegetative to reproductive growth. Increase to fortnightly soil drenches if not already doing so.
- Flowering. Maintain the foliar programme. This is the stage with the most direct bearing on eventual yield: pollen viability, flower retention and fruit set.
- Fruit set and fill. Continue foliar and soil applications through to harvest. Sugar in developing fruit comes from photosynthesis, and triacontanol keeps the photosynthetic rate high; the trace minerals supply the enzyme cofactors that turn photosynthate into sugars, acids and aroma.
Handling notes
Shake or stir well before every use. Do not mix with low-pH solutions; run a jar test to confirm compatibility with other products before tank mixing. Avoid spraying close to harvest on produce prone to staining, as the brown liquid can mark pale-skinned fruit. Do not pre-mix or store in diluted form. Use within 6 months of opening.
Works well combined with…
Brix+ delivers the signal; a base fertiliser delivers the building blocks. Use it alongside Organic All Purpose Fertiliser 4-4-4 during vegetative growth and switch to Organic Bloom Fertiliser 2-8-4 at flowering. Tank-mix with our soluble seaweed extract powder for a double seaweed pass, one for the hormone signal and one for mineral density. Apply our activated biochar condensate (wood vinegar) as a soil drench on alternate weeks for complementary karrikin signalling and microbial stimulation. Add humic acid flakes to soil drenches; the humic acid chelates the trace minerals in Brix+ for root uptake.
Storage
Store sealed in a cool, dry place out of direct sunlight. Crystallisation or sedimentation may occur below 5°C; this is normal and does not affect quality. Warm gently and shake to re-dissolve. Keep away from children and pets.
How Liquid Seaweed Brix+ works
Brix is the refractometer reading of sugar in fruit juice: a tomato at 4°Bx tastes watery, at 8°Bx it is properly sweet. Brix+ aims to move that number.
- Triacontanol lifts photosynthesis. A 30-carbon alcohol from leaf wax, active at nanomolar doses (Ries et al., 1977; Naeem et al., 2012).
- Seaweed switches on the plant's own signals. Extracts prompt the plant's cytokinin production, and betaines help chlorophyll and stress tolerance.
- The field record. Across 73 field studies, seaweed products raised yield by 15.2% and soluble sugar in fruit by 18.0% (Pei et al., 2024).
Figures describe published research on seaweed products, not a trial of Brix+.
References
- Ries, S.K., Wert, V.F., Sweeley, C.C. and Leavitt, R.A. (1977). Triacontanol: a new naturally occurring plant growth regulator. Science, 195(4284), 1339–1341.
- Naeem, M., Khan, M.M.A. and Moinuddin (2012). Triacontanol: a potent plant growth regulator in agriculture. Journal of Plant Interactions, 7(2), 129–142.
- Pei, B., Zhang, Y., Liu, T., Cao, J., Ji, H., Hu, Z., Wu, X., Wang, F., Lu, Y., Chen, N., Zhou, J., Chen, B. and Zhou, S. (2024). Effects of seaweed fertilizer application on crops' yield and quality in field conditions in China: a meta-analysis. PLOS ONE, 19(7), e0307517.
Use Liquid Seaweed Brix+ with
- Liquid Amino Acids Foliar Feed: tank-mix for quicker green-up and recovery.
- Organic Tomato Feed 3-4-6: the potash-led feed underneath, so the sugar has somewhere to go.
- Liquid Lawn Feed 7-2-3: spray together as a lawn recovery treatment after summer heat.
Which to choose: Brix+ is the ready liquid with triacontanol. Seaweed Extract Powder dissolves to make liquid seaweed at home: each gram makes 1.2 to 2 litres, so a 250 g pack makes 300 to 500 litres, and Scottish Kelp Meal is the granular version for soil.
Liquid Seaweed Brix+ FAQs
A biostimulant works on the plant's growth signalling; its nutrient content is small. Brix+ carries triacontanol alongside seaweed's natural growth compounds, where most seaweed feeds are dilute kelp.
No, it is a biostimulant (N 0.26%, K 1.65%), so keep feeding with a balanced organic fertiliser and use Brix+ on top.
Foliar at 2–2.5 ml per litre every 10–14 days, or a soil drench at 5–12.5 ml per litre every 4 weeks.
Yes. Spray at 2–2.5 ml per litre every 10–14 days, in the morning onto dewy grass. It is most useful after summer heat or ahead of a dry spell.
Usually. Jar test first: mix a little at the intended dilution and watch for clumping, sediment or a colour change.
It is a brown liquid and can mark pale fruit or light foliage close to harvest. On green leaves it is not noticeable.
Sealed, cool and out of direct sunlight, and use within 6 months of opening. Below 5°C it may throw a sediment; warm it gently and shake.
Often bought with this
Fertiliser
Bloom Fertiliser 2-8-4
Flowering-stage 2-8-4 — more blooms without a jungle of leaves.
from £12.00
