Myth of Vitamin B-1 that Refuses to Go Away

During the transplanting process at Bangan, Myanmar, the landscape contractor proffered a couple of plant "supplements", which are suppose to help the palms recover better from transplanting. No doubt recommended by his favourite garden centre. I had advised not to use Ferti-Start, which may cause iron toxicity and okay-ed the Bl-Plus, as it contains amino acid.

 Ferti-Start (containing Vitamin B-1 and Chelated Iron)

B1 Plus Super Start (containing Vitamin B-1, Amino Acid and Monopoly Saccharide)

The following is by Linda Chalker-Scott, PhD, who is widely known for her debunking of horticultural myths.

Superthrive and similar claims about products that tout the value of vitamin B-1 and or synthetic auxins as "tonics" that have value when used on a regular basis.

Applying vitamin B-1, or thiamine, to root systems of whole plants does not stimulate root growth. This is a myth that refuses to die, though it has been repeatedly refuted in the scientific literature. To understand why, it helps to think about this in a historical perspective.

Many decades ago the plant growth regulators called auxins were isolated and characterized. Auxins were found to stimulate cell elongation in both root and shoot tissues. Commercial preparations were developed that contained auxin and vitamin B-1 among other ingredients. Research in 1949 found improved root development in plants treated with one of these preparations (Transplantone, which contains both auxin and thiamine), but noted the importance of auxins in this response. Further research throughout the last half of the 20th century investigating the application of auxins to root systems suggested that auxins may stimulate root growth, but that vitamin B-1 on its own does not.

Indole butyric acid (IBA) is one of the most common auxin formulations especially in tissue culture. In cuttings, it has been found to increase the number of roots, to increase rooting percentage, to increase both parameters, or to do neither. IBA has had some success in root regeneration in transplanted trees; it may help redirect resources to the roots by suppressing crown growth.

Naphthylacetic acid (NAA) is also a commonly used auxin and often the active ingredient in commercial preparations. NAA tends to be toxic to seedling root development, as it inhibits primary root growth and enhances lateral root growth. This latter activity may account for NAA’s success in regenerating roots of transplanted and root-pruned trees. Like IBA, NAA apparently suppresses crown growth, which also may redirect resources to the roots.

Vitamin B-1 (thiamine) is an important component of tissue culture media, in which isolated plant tissues can be propagated. Its use for stimulating root growth in whole plants is not supported in the literature and one study reported that root growth was greater in the control treatment (water) than with thiamine. Plants in the field manufacture their own source of thiamine and it is therefore unnecessary to add any additional levels. Many fungi and bacteria associated with plant roots also produce thiamine, so it’s likely that healthy soils will contain adequate levels of this vitamin without amendment.

The Bottom Line

• Vitamin B-1, aka thiamine, does not reduce transplant shock or stimulate new root growth on plants outside the laboratory.
• A nitrogen fertilizer is adequate for transplanting landscape plants; avoid use of “transplant fertilizers” that contain phosphate.
• Healthy plants will synthesize their own thiamine supply.
• Healthy soils contain beneficial microbes that synthesize thiamine as well.
• Difficult-to-transplant species may be aided by application of auxin-containing products in addition to nitrogen, but read the label and don’t add unnecessary and potentially harmful chemicals (this includes organics!).
• Adequate soil moisture is crucial for new root growth; be sure to irrigate new transplants frequently and use mulch to reduce evaporation".