Seaweed Extract, Humic and Fulvic Acid, Amino Acids for Plants
Plant additives go in alongside the base feed for one job, and the words on the bottle - seaweed extract, humic and fulvic acid, amino acids, vitamins - say what is in it, not what it does. This guide explains what each is sold for, which can be sprayed, and how to choose. The whole range is in our other additives section, with the growth and bloom stimulants alongside.
What the words on the bottle mean
None of these replaces the base feed: the SUPERthrive page spells out that it has no NPK. Most are sold for plant health - coping with stress, better uptake of the feed - and some for flowering.
- Seaweed extract is the best known. The Biobizz Alg-A-Mic page lists micronutrients, vitamins, amino acids and plant hormones in its cold-pressed concentrate and sells it for stress: overfeeding, deficiencies, pests and swings in temperature or humidity. The Buddhas Tree Advanced Meta-Boost page names auxins and cytokinins from seaweed.
- Humic and fulvic acids mostly come from leonardite, a natural deposit rich in humic substances (the Biobizz Top Max and T.A. Fulvic pages name it as their source), and are sold for uptake: Top Max frees up calcium, iron and magnesium and T.A. Fulvic lets plants absorb more minerals, their pages say.
- Amino acids are the building blocks of proteins, as the Biobizz Bio Heaven page puts it. The Dutchpro Amino Strength page sells them for growth, nutrient uptake and coping with heat and drought, and the Meta-Boost page says they chelate nutrients (bind them so the plant can take them up).
- Silicon is a separate class (stronger cell walls and thicker stems, its makers say). House & Garden Amino Treatment pairs mono-silicic acid with amino acids; for silicon alone see our silicon additives and the glossary.
Ten additives compared
| Additive | Its page lists | Dose on its page | When | Spray? |
|---|---|---|---|---|
| Biobizz Alg-A-Mic | Cold-pressed seaweed, vitamins, amino acids | 2-4 ml per litre (chart) | Veg to flowering week 8 (Light Mix and Coco Mix chart) | Yes: 1-2 ml per litre |
| Buddhas Tree Advanced Meta-Boost | Seaweed auxins and cytokinins, amino acids | 0.5 ml per litre; 0.5-1.5 in flowering | Veg; from flowering week 4 | – |
| Biobizz Top Max | Humic and fulvic acids | 1-4 ml per litre (chart) | Flowering only | – |
| T.A. Fulvic | Fulvic acid | 2 ml per litre | Every feed, to early flowering | Yes: 2 ml per litre |
| Biobizz Bio Heaven | Amino acids, aged humus | 2-5 ml per litre (chart) | Propagation to the last feed week | – |
| House & Garden Amino Treatment | Mono-silicic acid, amino acids | 1 ml per litre, added first | Veg to flowering week 2 or 3 | – |
| Vitalink Turbo Plus | B vitamins, fulvic acid, amino acids, seaweed | 1-2 ml per litre; 1 ml in hydro | Last two veg weeks to the flush | – |
| Vitalink Hydrate | Hormones, amino and humic acids, betaines | 0.2-0.6 ml per litre by drought risk | Early veg to late flowering | Yes, in sudden drought; rate on the label |
| Vitalink Heat | Bio-stimulant for cold | 0.3-0.5 ml per litre | Below 5°C | Yes: 5 ml per litre weekly |
| Plant Magic Evolution 2.0 | Humic and fulvic acids, hormones, amino acids | Ready to use; 1-2 times a week (chart) | Grow week 1 to bloom week 2 | Spray only |
The (chart) doses are in the Biobizz feed chart and the Plant Magic feed chart. Two more go in at the rate on the label: Essentials Plus Fulvic and Ruby Ful#$% (registered as a molybdenum fertiliser). Dutchpro's own chart gives Amino Strength at 0.4 ml per litre once a week.
One note from our own pages: customers find Bio Heaven keeps plants healthy but does little for fruit size or yield. With any new additive, start at about half the maker's rate, as the Meta-Boost page says; our advice is to add one new bottle at a time.
Vitamin tonics: SUPERthrive, Hesi SuperVit and B-52
- SUPERthrive: 0.09% vitamin B1 and 0.048% of the hormone NAA, in use since 1940, its page says; one drop per four litres of water, as a guide, or sprayed under the leaves.
- Hesi SuperVit: vitamins and amino acids at 1 ml per 65 litres (the 10 ml bottle has a dropper top), every week until the flush on the Hesi feed chart.
- Advanced Nutrients B-52: vitamins and minerals at 2 ml per litre, grow weeks 1-4 and bloom weeks 3-7 on the Advanced Nutrients feed chart; for heat, drought and transplant shock, its page says.
Can it be sprayed? Foliar feeding
The Biobizz feed chart's note says Alg-A-Mic and Biobizz Acti-Vera (aloe vera) can be sprayed until the second week of flowering; T.A. Fulvic sprays at 2 ml per litre, Essentials Plus Fulvic at the rate on the label, Heat at 5 ml per litre weekly and not to run-off, and Evolution 2.0 is only ever a spray. Our Alg-A-Mic page says: in anything but soil, use it only as a spray.
Spray with the lights off or the sun low so the droplets do not scorch the leaves, the Super Boost page says, and keep it off lamps and electrics; the Optic Foliar Transport page says it lets sprays work under lights.
Which should I choose?
- Start with your feed maker's chart. Biobizz growers have Alg-A-Mic, Bio Heaven, Acti-Vera and Top Max on the Biobizz chart; Plant Magic growers spray Evolution 2.0; Advanced Nutrients growers add B-52; Hesi growers SuperVit. Essentials Plus Fulvic is made to get more out of the Vitalink range, its page says. Mixing brands? T.A. Fulvic and Evolution 2.0 say any nutrient range; Meta-Boost, Hydrate, Amino Strength and Ruby Ful#$% any medium or system.
- Match the job. A stressed plant: SUPERthrive. Hot spells or missed waterings: Hydrate, started a week or two ahead. Below 5°C: Heat (half doses of each if you run both, the Vitalink pages say). Young plants: Mills Start R (fulvic, humic and L-amino acids, label rate) or another root stimulant. Flowering: Top Max, Turbo Plus or Meta-Boost (see our PK boosters guide first).
- Mix in order, stop for the flush. Amino Treatment goes in first, mixed before anything else; add the rest after the base feed, one at a time, and check the pH last - the Essentials Plus Fulvic page says to check it after adding that one (pH and EC meters). Turbo Plus stops at the flush, Meta-Boost and Hydrate a week before harvest.
Quick answers
What does seaweed extract do for plants?
A tonic, not a feed. The Alg-A-Mic page sells it to help plants through stress and, sprayed, for greener leaves. Seaweed-based root stimulants such as Canna Rhizotonic and Vitalink Rootstim are compared in our root stimulants guide.
Humic acid or fulvic acid?
Two fractions of the same humic substances; fulvic is the smaller, more soluble one. For a bottle to add to your usual feed, it is fulvic that is sold on its own (T.A. Fulvic, Essentials Plus Fulvic, Ruby Ful#$%); humic only comes blended, in Top Max for flowering, Hydrate, Evolution 2.0 and Mills Start R.
What do amino acids do for plants?
The building blocks of proteins, sold for growth, nutrient uptake and coping with stress: Bio Heaven, Amino Strength and Amino Treatment; most mixed tonics carry some.
What does SUPERthrive do?
A vitamin B1 and hormone (NAA) concentrate with no NPK, for stressed plants and transplant shock, its page says. Best as a one-off, in our view; for everyday use, Hesi SuperVit.
More Growers' Guides
- Root stimulants and rooting gels
- PK boosters and bloom boosters
- Which nutrients? Soil, coco and hydro
- Hydroponics: the systems explained
Not sure what you need? Call the shop on 0117 971 3000 or pop in to the Bristol store and we'll help you pick.