First, the study of vitamins as they are used by plants is relatively new. The factual data is limited, while the assumptions and false claims are already running rampant. Before adding anything to your soil, conduct a lab-based soil test.
 
Next, let me tell you that the currently available research is some pretty thick reading. I’m not going to delve deeply because I want you to keep reading and I want what you read to be useful. If you want more in-depth information, check out  “Benefiting others and self: Production of vitamins in plants” by Yufei Li, et al, and “Vitamins and Their Effects on Plant” by Hayder Abid Alrazzaq, et al.
 
We will take a far more simplified view while retaining the facts.
 
What are vitamins?
 
There are four nutrient groups: amino acids, fatty acids, minerals, and vitamins. Vitamins are molecules, or groups of molecules, used in very small amounts by living things for proper metabolism. Very often, plants can make or synthesize their own vitamins, but rarely can they produce as much as they need. The rest must come from elsewhere.
 
How do plants use vitamins?
 
Plants use vitamins much the way we do. Vitamins are like puzzle pieces [coenzyme regulators] that bring together important physiological processes:

• Counteract environmental stress
• Fight disease
• Increase crop yields
• Maintain proper cell function
• Protect against rot
• Regulate growth and development
• Resist salinity stress
• Support photosynthesis

 
But too much of a good thing can be a bad thing. For example, too much vitamin B6 can make diseases worse for plants.
 
Which vitamins do plants use?
 
Plants use many of the same vitamins we do. I can tell you that reading the Latin names of some of these made it easy to see why we use abbreviated letters and numbers!
 
Here is a list of the vitamins used by plants and what we currently know about them:

• Ascorbic acid (C)—Promotes vegetative and reproductive growth, activates photosynthesis, enhances seedling growth but delays flowering
• Biotin (H)—Regulates construction and destruction within the plant, critical to the Krebs cycle
• Cobalamin (B12)—Acts as a cofactor for several enzyme functions
• Ergocalciferol (D2)/cholecalciferol (D3)
• Folates (B9)—Promotes vegetative and reproductive growth and cell division, supports photosynthesis, helps fight against Pseudomonas syringae, cucumber mosaic, and several Xanthomonas/leafspot diseases
• Niacin/nicotinamide adenine dinucleotide (B3; NAD)—Primary focus on root development, DNA repairs, metabolism, pollen fertility, silique growth, and stress responses
• Pantothenic acid (B5)—Promotes vegetative and reproductive growth, supports metabolism and photosynthesis
• Phylloquinone/menaquinones (K)
• Pyridoxine (B6)—Critical to early root development, an important part of most biochemical changes related to growth
• Retinol/β-carotene (A)—Growth regulator at the cellular and tissue level
• Riboflavin (B2)—Used in breaking down amino acids, photosynthesis, and other metabolic processes, helps combat bacterial speck in tomatoes, downy mildew, Alternaria leaf spot, and tobacco mosaic, helps produce growth hormones (auxins)
• Thiamine (B1)—Functions as a growth regulator and stimulator, reduces membrane permeability, improves photosynthesis, activates antioxidant enzymes, especially important when growing corn, helps fight leaf blight and sheath blight, and is a major player in the Krebs Cycle, nitrogen assimilation, and the Calvin cycle
• Tocopherol/tocotrienol varieties (E)—Maintains membrane stability, found throughout the plant in chloroplasts where it supports photosynthesis, regulates growth and development, and reduces the negative effects of physical stress

 
We also know embryonic and early seedling death can occur when the synthesis of vitamins B1, B2, B3, B5, B6, B7, B9, and E is disrupted. Note that I said disrupted and not absent from the soil. Plants manufacture many of these vitamins.
 
But how does all this help you be a better gardener?
 
Your soil test will not tell you which vitamins are present. Vitamin deficiencies and toxicities in plants is a relatively new science. There are no handy tips, tools, tests, or solutions. Not yet anyway.
 
As the nutritional values of many food crops continue to decline, research has focused on increasing vitamin levels in the plants we eat. This process is called biofortification. In many cases, these plants are genetically modified (GMOs). Other times, it is simply a matter of selective breeding. Unfortunately, I do not have access to a list of which is which at this time. The good news is that as more research is conducted, we are likely to have access to more useful information.
 
The best way to ensure your plants have everything they need to grow and thrive is to top dress your soil with alfalfa meal, blood meal, compost, and aged manure. And keep reading and learning about new discoveries related to plants, vitamins, and gardening!

Alfalfa is a legume, like peas and beans, so it can fix atmospheric nitrogen. But it grows more like oats and barley. Before it goes to seed, deep-rooted alfalfa plants improve soil structure and make more nitrogen available to neighboring plants.
 
If you cut those plants down, ferment, dry, and grind them up, you have alfalfa meal.
 
How does alfalfa meal help in the garden?
 
Alfalfa meal adds nitrogen, a fatty-acid growth stimulant (triacontanol), and trace minerals, like Vitamins A, B, and E, magnesium, and iron to your soil. Triacontanol stimulates root and stem growth in young plants. Generally speaking, alfalfa meal has an NPK value of 3-1-2. This means it contains three parts nitrogen (N), one part phosphorus, and two parts potassium.
 
Amending your soil with alfalfa meal improves its structure by helping to build better soil aggregates. Those are the clumps of soil that hold water and nutrients while allowing roots and gases to move around freely.
 
What is alfalfa meal?
 
While you can certainly mulch your garden with alfalfa hay, it may take a while to break down into nutrients your plants can use. Alfalfa meal eliminates that lag time by grinding dried alfalfa up into a fine powder. The powder is then used as-is or pressed into cubes or pellets. Because these pellets are made from a finely ground powder, they decompose quickly. They decompose so quickly that they can jump-start your compost pile if conditions have slowed the heating process.
 
How to use alfalfa meal
 
Alfalfa meal decomposes so quickly that it can create significant amounts of heat. Alfalfa meal is spread on top of the soil. You can either rake it in or cover it with mulch to prevent it from blowing away, using the following application amounts:
 

• Light applications—12 pounds per 1,000 sq. ft.
• Medium applications —25 pounds per 1,000 sq. ft.
• Heavy applications—50 pounds per 1,000 sq. ft.

 
You can also sprinkle ¼ to ½ cups of alfalfa meal around individual plants.
 
Problems with alfalfa meal
 
Alfalfa meal can attract mice, rabbits, rats, and other herbivores to your garden. You can get around this problem by using loose meal instead of pellets. Apparently, those creatures find licking up alfalfa powder too time-consuming.
 
Alfalfa meal is generally free of weed seeds, but lower-quality alfalfa meal may contain alfalfa seeds. In my opinion, that’s fine because alfalfa is a great addition to the landscape, but you may feel differently, so buy accordingly.
 
Most livestock-grade alfalfa is genetically modified and specifically engineered to withstand heavy doses of pesticides. [The name ‘Roundup Ready’ should be a clue.] If you want to avoid GMOs and keep those chemicals out of your garden, buy organic alfalfa meal from a reputable seller. Look for the OMRI-certified label on the container.
 
Of course, you can always grow your own alfalfa. Its roots reduce soil compaction, the flowers are lovely and attract pollinators, and once it starts growing, plants can live for up to 20 years! Read my post on alfalfa to learn more about growing your own.
 
How to make your own alfalfa meal
 
If you want to make your own alfalfa meal, cut your alfalfa when plants start to flower and ferment the silage for a couple of weeks in an anaerobic environment. This is then dried and ground into a powder. Personally, I’m not sure my coffee grinder or food processor would be the same after grinding up a load of alfalfa. Of course, buying ready-made is simpler, but alfalfa is still nice to have in your landscape.

Some people use alfalfa meal to make a fertilizer tea. If you’d like to try your hand at this, use the following steps:
 

1. Put 5 gallons of tap water in a large bucket and let it sit for three days to allow the chlorine to dissipate.
2. Stir in 4 cups of alfalfa meal (any form) and cover with a lid.
3. Stir once or twice every day for one week.
4. Apply your alfalfa tea as a foliar spray or pour it on the soil.

 
Whether you use alfalfa meal or alfalfa tea, the best time to apply it is after your seeds have germinated.

Alfalfa contains chemicals that can slow or halt the germination of many crops. But the nutrients provided will help your seedlings thrive once they’ve sprouted. Research has shown that soil amended with alfalfa has a healthier microbial community than soil amended with only composted manure. Those bacteria support plant health, resulting in earlier and better yields. Your strawberries will be bigger, sweeter, and ripen earlier.
 
Alfalfa meal is also said to make life difficult for root-knot nematodes, but the research does not support these claims. In fact, nematodes are alfalfa pests. Oh, well.