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How to Use Probiotics in the Garden to Nourish Plants

Amelia has been an avid gardener since childhood and enjoys experimenting with natural and sustainable gardening methods.

I use garden probiotics throughout my yard. They really help with transplant shock and boost growth.

I use garden probiotics throughout my yard. They really help with transplant shock and boost growth.

Probiotics Help Your Garden's Health, Too

You have heard how important probiotics are to your health, but what about the health of your garden? Have you considered fortifying your perennials with a probiotic foliar spray or giving your fruit trees a probiotic boost next time you water? I had not even thought of this myself until recently, but I'm excited about the results seen in my garden.

What Kind of Probiotic Do You Use on Plants?

While you really could use just about any probiotic to give your garden a boost, I use a solution of cultured molasses because of the impressive mineral profile. Molasses is rich in iron, magnesium, and calcium, all of which are as necessary for plants as they are for people. A recipe for this culture is provided below.

Do Plants Need Probiotics?

Just like us, plants need beneficial bacteria to protect them inside and out. With a healthy probiotic colony, plants are protected from molds or other pathogens and are even better equipped to deal with insect attacks.

Their use dates back at least to 17th century Japan when an agricultural revolution swept the country. Family farmers developed potions called bokashi, specially adapted to their area, to nourish and protect their crops. Today, bokashi is manufactured commercially in Japan and is available elsewhere under the name "effective microorganisms" or "EM."

Wholesome Sweeteners makes a wonderful and nutritious molasses.  I measured only to verify the recipe for the sake of accuracy, but once you get the hang of it, you will be able to add a good-sized dollop instead.

Wholesome Sweeteners makes a wonderful and nutritious molasses. I measured only to verify the recipe for the sake of accuracy, but once you get the hang of it, you will be able to add a good-sized dollop instead.

How to Make the Starter Culture

This recipe can be used to start garden probiotics from scratch as well as to propagate your culture in batch after batch.

Supply List

  • 2 one-quart mason jars with bands and lids
  • 1/4 cup unsulphured, organic molasses for each batch
  • 1 capsule quality probiotic OR 1/4 cup garden probiotic from your last batch


  1. Add 1/4 cup molasses to one of the jars.
  2. Open probiotic capsule and empty contents onto molasses in jar OR use a quarter cup of garden probiotic from your last batch.
  3. Add water until fluid reaches the jar's shoulder.
  4. Cover with lid and band and shake until molasses is dissolved.
  5. Place in a warm place (80 to 90 degrees Fahrenheit) until a white/gray substance settles on the bottom (1 to 7 days).
  6. Use or refrigerate.

What a Successful Batch Should Look and Smell Like

  • A white/gray substance on the bottom is the result of successful culturing.
  • If the culturing was successful, the result should be bubbly and possibly have a thin white film (not mold).
  • It should smell like molasses, but brighter. If you like molasses, you will probably also enjoy the flavor (go for it! It is great for you as well as for your garden).

If you have been successful, this will be the starter culture for future batches (instead of the probiotic capsule).

Tips and Tricks

  • Whenever a jar gets down to about half a cup, add another 1/4 cup molasses and water up to the jar's shoulder and repeat. Refrigerate.
  • To tell how far along the process is, look for the white substance at the bottom. If it is completely white, the process is probably complete.
  • There is a fair amount of leeway on the timing of the culturing process. There is a lot of sugar in molasses, and the beneficial bacteria will keep on eating it for some time. I use the culture before all the sugar is used up so that the bacteria will have something to eat as they begin colonizing the plants. It also tastes better that way. However, make sure it is nice and bubbly so that the solution will not attract bugs.
  • Other factors affect culturing time as well. Up to around 100 degrees Fahrenheit, the warmer the solution, the faster it will culture. Also, in my experience, the first batch takes about a week, but subsequent batches take less time. If used and refreshed frequently, the culture stays stronger, and culturing will go faster.

How to Apply the Garden Probiotics

Garden probiotics can be used three ways in your garden:

  1. Diluted and used for watering
  2. Diluted and used to spray foliage
  3. Added to livestock water

I occasionally water the trees and shrubs with it, but normally I use the foliar spray because foliage can absorb the nutrients more efficiently than roots (since the solution diffuses in the soil and not all of it makes it to the root), and the beneficial bacteria will be able to colonize the foliage immediately.

I aim to use the foliar spray every 2 to 4 weeks during the growing season. If you use kelp liquid fertilizer or another natural liquid fertilizer, it can be mixed in with this application.

Method 1: Watering

To water with garden probiotics, simply:

  1. Dilute one part garden probiotics with 10 parts water. That's about 3/4 cup per gallon of water.
  2. Use immediately on any plant.

This is a great way to get your perennials off to a good start early in spring. Use it again in the fall as the plants go dormant. A good culture will also help your indoor starts.

Method 2: Spraying Foliage

To make a foliar spray, simply:

  1. Dilute one part garden probiotics with 10 parts water in a spray bottle. Many spray bottles come with marks for dilution. Fill the bottle to the 10:1 mark, then fill the rest of the way with pure water.
  2. Replace nozzle and spray on any part of any plant.

Method 3: Adding Probiotics to Livestock Water

To share it with your chickens or other animals, simply mix a small amount with their water (about 10:1). My birds love it.

Best Probiotic

Which Ingredients Are Best?

  • You will get what you pay for. That said, the original batch of starter culture cost me about 65 cents, and subsequent batches cost less than 30 cents per quart. A quart can make several gallons of foliar spray.
  • Starting with a quality probiotic means you have billions of organisms in dozens of strains. You are unlikely to acquire all these strains unless you start with a good base.
  • Using organic, unsulphured molasses means a pure substrate, free from poisons that may kill desirable bacteria or even the plants you are trying to nourish.
  • Using pure, unchlorinated water means no harmful chlorine or fluorine to jeopardize your culture.

Strengthen Your Garden With Probiotics

This method of nourishing plants and ecosystems has stood the test of time and deserves to be a part of our gardening. Probiotics can enhance the health of your plants and garden as a whole, making it stronger and more resistant to infestation.

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

Questions & Answers

Question: Are you using probiotics mix capsules made for human consumption or ones that are specifically for plants? I haven't been able to find capsules specifically for plants.

Answer: I use probiotics for humans.

Question: Why does this recipe require a cup of molasses but you only used 1/4 cup?

Answer: Good question. That was not clear, and I will change it. However, to keep your culture alive, you will want to continue to make new batches, using 1/4 cup molasses each time. Thanks for point this out.