Fulvic acid benefits for plants: 8 trial results

By Joe Barrington, founder of Dr Forest · Published May 2026 · Updated 23 October 2026

Quick answer. The fulvic acid benefits for plants that show up in peer-reviewed trials are better nutrient uptake, more root, and better drought and salt tolerance. In those trials, that meant up to 35% more tomatoes and 53% more rose flowers by weight. It does most for plants under pressure, such as those short of iron or phosphorus or heading into a dry spell. It never replaces a feed or compost.

What I've seen in practice

I've seen fulvic acid work on a variety of crops. What I notice is faster growth and a better yield, and I put that down to the plant taking up more of the nutrients and fertiliser it is given.

Several of the pot and field trials below used far stronger doses than a garden needs. A garden spray or drench of fulvic acid powder is mixed at 0.5 to 1 g per litre, and how to apply fulvic acid has the rates and timings.

Eight peer-reviewed fulvic acid benefits for plants

1. Better nutrient uptake

Rice seedlings short of phosphorus took up 18 to 21% more of it with a lab-grade fulvic acid at 40 to 80 mg/L, and grew about 25% more at 40 to 60 mg/L. When the solution was buffered so the roots couldn't make it more acidic, the gain disappeared [1]. In tomato seedlings grown in a nutrient solution, 80 mg/L more than doubled the iron in the leaves [2].

2. More root

In the same tomato seedlings, 80 mg/L made the roots 44% longer with 14% more root tips, and whole-plant growth peaked at 160 mg/L [2].

3. Better drought tolerance

Oats in pots, sprayed three times with 600 mg/L through a drought, had about 23% more leaf water and 24% more chlorophyll than unsprayed plants in the same drought [3].

4. Less blossom-end rot in tomatoes

In a Korean trial, tomatoes sprayed three times at 0.8 g/L in the month after planting out grew bigger and gave more marketable fruit. Blossom-end rot fell at every rate and didn't appear at all at 1.6 g/L, though that rate held growth back [4].

Uneven watering causes most cases of tomato blossom end rot, so get the watering steady first.

5. Higher yield

A corn-straw fulvic acid mixed into 5 kg pots of soil at 2.7 g per kg raised tomato yield by up to 35%, through more fruit, with no change in fruit sugars or aroma [2]. Tripling the rate gave no further gain, and a 100 mg/L leaf spray didn't add growth. That dressing works out at 13.5 g of fulvic acid in a single pot, more than a garden drench puts on a whole square metre.

6. Salt tolerance

Barley on salty clay in Egypt, sprayed with a potassium fulvate over two winters, gave about 11% more grain with full phosphate than phosphate alone, and with three-quarters of the phosphate it still beat full phosphate on its own [5]. Salty soil is rare in UK gardens, so this matters most near the coast or beside a gritted road.

7. More antioxidants in produce

Pistachio trees sprayed with 1.5 g/L in late June and late August gave kernels with 31.8% more phenolic compounds, according to the authors [6]. The trial measured kernel quality, not yield.

8. More flowers

Damask roses in Saudi Arabia, sprayed four times a fortnight apart with lab-grade fulvic acid at 5 g/L, gave 19.8% more flowers and 52.8% more flower weight per hectare than roses sprayed with water. At 3 g/L the result was much the same [7].

How fulvic acid compares with other biostimulants

On greenhouse sweet pepper in Egypt over two seasons, fulvic acid worked into the soil gave more fruit per plant than compost tea, effective microorganisms (EM) or yeast extract. Compost tea matched it on total yield and EM came last [8]. The best vitamin C, sugars and carotenoids came from fulvic acid paired with a seaweed biostimulant sprayed on the leaves. The fulvic acid went on at 50 g per square metre, ten to twenty times a garden drench.

Fulvic acid for lawns

Spray in late spring, before the lawn dries out. The drought help measured on oat, a cereal grass, came from spraying through the dry spell [3]. It won't bring back a lawn that has already gone brown.

Fulvic acid for flowers

Expect less on a garden rose than the Damask rose trial found. It used a lab chemical at 5 g per litre, five to ten times a garden spray.

Fulvic acid for fruit

Young apple rootstock (M9T337) grown in a nutrient solution put on more dry weight and used nitrogen better with fulvic acid, best at 120 mg/L of the five rates tested, which went up to 240 mg/L [9].

Fulvic acid for vegetables

On processing tomato in arid, salty fields in north-west China over two seasons, yield, fruit quality and water use peaked at the middle of three rates, 50 kg per hectare (5 g per square metre), and fell back at 75 kg [10].

In drought-stressed tomato seedlings, 400 mg/L was the best of six rates tested, and seedling sprays later gave about 28% more fruit per plant [11].

Peas and beans go both ways. In 20 Ontario field trials on fertile soils, fulvic acid did nothing for dry bean vigour or yield, even at eight times the recommended rate [12]. On field peas grown on clay loam in Egypt over two winters, seed soaked in fulvic acid at 3 g/L before sowing gave 69 to 75% more green seed per plant than plants sprayed with water [13]. That soak is nearly forty times the 80 mg per litre seed rate on the label, so don't copy it at home.

Four limitations

• Products vary. In a 2025 lab screen, only 14 of 25 commercial products sold as fulvic acid contained a real fulvic fraction [14]. What fulvic acid is explains that fraction.
• Well-fed plants gain least. Results in this post run from 35% more tomatoes in pots to about 11% more barley on salty clay to nothing on the Ontario beans.
• More isn't better. Container tomatoes in peat compost were set back by a liquid fulvic product drenched at higher rates, possibly through too much iron and manganese, while a leaf spray of the same product made the leaves greener [15].
• It can't replace organic matter. A spray won't do the work of compost, mulch and soil life.

How it pairs with humic acid is in humic acid vs fulvic acid, and humic acid's own trials are in the benefits of humic acid for plants. Both acids sit in the humic and fulvic range.

FAQ

Q: What are the main benefits of fulvic acid for plants? Better nutrient uptake, more root, and better drought and salt tolerance. The strongest single results are about 35% more tomatoes in pots and 53% more Damask rose flowers by weight.

Q: Does fulvic acid actually work in field trials? It helped barley on salty soil, processing tomato in salty fields and field peas. Twenty Ontario dry bean trials on fertile soils found no effect.

Q: Which plants benefit most from fulvic acid? Plants under stress gain most: those short of phosphorus or iron, heading into a drought or growing on salty soil. Well-fed plants on fertile ground, like the Ontario dry beans, gained nothing.

Q: Is fulvic acid good for roses? It helped in one trial in Saudi Arabia: Damask roses sprayed at 5 g per litre, five to ten times a garden spray, gave 52.8% more flowers by weight.

Q: Does fulvic acid help tomatoes? Yes, in two trials: a 0.8 g per litre spray cut blossom-end rot and raised marketable yield. A soil dressing of 2.7 g per kg in pots raised yield by up to 35%.

Q: Does fulvic acid help with drought stress? Yes, if it goes on before or early in a dry spell. It helped oat and tomato plants cope with drought, but it won't revive a plant that has already wilted.

Q: Is fulvic acid better than compost tea, EM or yeast extract? In the one sweet pepper trial that compared all four, fulvic acid and compost tea gave the same total yield, and EM came last.

Joe Barrington

Founder of Dr Forest in Stockport. Joe formulates and blends his own range of feeds and stocks other soil products alongside them, including this fulvic acid.

Sources cited

1. Lv, X. et al. (2024). Fulvic acid application increases rice seedlings performance under low phosphorus stress. BMC Plant Biology 24: 703. doi.org/10.1186/s12870-024-05435-4
2. Zhang, P. et al. (2021). Dose-dependent application of straw-derived fulvic acid on yield and quality of tomato plants grown in a greenhouse. Frontiers in Plant Science 12: 736613. doi.org/10.3389/fpls.2021.736613
3. Zhu, S. et al. (2024). Integrative transcriptome and metabolome analysis reveals the mechanism of fulvic acid alleviating drought stress in oat. Frontiers in Plant Science 15: 1439747. doi.org/10.3389/fpls.2024.1439747
4. Suh, H.Y.; Yoo, K.S.; Suh, S.G. (2014). Effect of foliar application of fulvic acid on plant growth and fruit quality of tomato (Lycopersicon esculentum L.). Horticulture, Environment, and Biotechnology 55(6): 455 to 461. doi.org/10.1007/s13580-014-0004-y
5. Alsudays, I.M. et al. (2024). Applications of humic and fulvic acid under saline soil conditions to improve growth and yield in barley. BMC Plant Biology 24: 191. doi.org/10.1186/s12870-024-04863-6
6. Nikoogoftar-Sedghi, M. et al. (2024). Fulvic acid foliar application: a novel approach enhancing antioxidant capacity and nutritional quality of pistachio (Pistacia vera L.). BMC Plant Biology 24: 241. doi.org/10.1186/s12870-024-04974-0
7. Ali, E.F. et al. (2022). Ginger extract and fulvic acid foliar applications as novel practical approaches to improve the growth and productivity of Damask rose. Plants 11(3): 412. doi.org/10.3390/plants11030412
8. Mohamed, M.H.M. et al. (2021). Impacts of effective microorganisms, compost tea, fulvic acid, yeast extract, and foliar spray with seaweed extract on sweet pepper plants under greenhouse conditions. Plants 10(9): 1927. doi.org/10.3390/plants10091927
9. Yu, B. et al. (2023). Effects of fulvic acid on growth and nitrogen utilization efficiency in M9T337 seedlings. Plants 12(23): 3937. doi.org/10.3390/plants12233937
10. Zhou, Z. et al. (2026). Optimizing processing tomato yield and quality in arid saline-alkali fields through appropriate fulvic acid application combined with aerated irrigation. Irrigation Science 44: 10. doi.org/10.1007/s00271-025-01054-5
11. Song, H. et al. (2025). The impact of fulvic acid on the growth physiology, yield, and quality of tomatoes under drought conditions. Agronomy 15(7): 1528. doi.org/10.3390/agronomy15071528
12. Mahoney, K.J. et al. (2017). Fulvic and humic acid fertilizers are ineffective in dry bean. Canadian Journal of Plant Science 97(2). doi.org/10.1139/cjps-2016-0143
13. Mahdy, R.M. et al. (2024). Evaluation of two different methods of fulvic acid application (seed priming and foliar spray) on growth, yield, and nutritional quality of pea (Pisum sativum L.). Plants 13(23): 3380. doi.org/10.3390/plants13233380
14. Vialykh, E.A. et al. (2025). Use of a spectrophotometric method for the detection of adulterants in commercial fulvic acid products. Journal of AOAC International 108(6): 828 to 839. doi.org/10.1093/jaoacint/qsaf073
15. Quijia Pillajo, J. et al. (2024). A biostimulant containing humic and fulvic acids promotes growth and health of tomato 'Bush Beefsteak' plants. Horticulturae 10(7): 671. doi.org/10.3390/horticulturae10070671