A BRIX Boost Recipe

If you’ve been following along our BRIX post series, you know that high BRIX levels come from healthy soil, happy microbes, and efficient photosynthesis.

Consistent, long-term high BRIX levels happen when we support the soil and microbes over time. But while we’re working toward that, we can help our dahlias along with a temporary BRIX boost foliar spray / soil drench.

A Foliar Spray for Temporary BRIX Boosts

This past season on our farm, we experimented with an all-natural foliar spray that included humic acid, fulvic acid, kelp meal, fish emulsion, and unsulfured blackstrap molasses. We didn't just pick these ingredients willy nilly. From our understanding:

• Humic acid helps unlock nutrients in the soil

• Fulvic acid helps carry nutrients into plant cells

• Kelp meal encourages stronger, healthier leaves and roots and is packed with micronutrients

• Fish Emulsion is an organic nitrogen source with trace minerals that helps with leaf growth

• Unsulfured Blackstrap Molasses is microbe candy, or quick energy for microbes, also with trace minerals

I am certainly not the only one doing this and I didn't make this concoction of ingredients up on a whim. I checked the ingredient lists of other products on the market—including Warren Vigor's Vigor Plant Booster that people rave about—and then sourced my own concentrates of those ingredients from my fancy farm store, Amazon.

There are other products on the market that have a similar ingredient list but may be missing one or two of them. One of them is Nature's Way Soil Liquid Humic & Fulvic Acid Concentrate. It seems to be easier to get your hands on than the Vigor Plant Booster (which is sometimes out of stock) but it's missing unsulfured blackstrap molasses so to those who use this one on their dahlias (like my parents), I recommend purchasing a molasses concentrate to add it to the mix.

An early-season photo of our dahlia field.

Our Farm’s BRIX Boost “Recipe”

Here's the "recipe" we used last season! Please note that we calculated these amounts per gallon of water by reading the label on each product. So depending on what product you find, please please follow the application rate on the product you purchase.

• 2 Tbsp. unsulfured blackstrap molasses

• 1/4 cup liquid humic and fulvic acid combo (I can't find the one I used to use. This one looks like it has both)

• 1/4 cup liquid kelp

• 2 Tbsp. fish emulsion (stop using once buds start forming)

We applied this every two weeks last season, and we plan to follow a similar schedule.

The Results

As I mentioned in a previous blog post, the results of us using this spray every two weeks were promising: dark green thick leaves, fewer leaf-chewing pests (idiot grasshoppers were around and even on our dahlias but largely left them alone), and rare leaf chlorosis.

Because what we saw on our farm was so encouraging, I've continued digging into others' research in the off season. This podcast and this article are AMAZING reads.

What I’ve learned is that while our dahlias clearly responded well to foliar applications of these micronutrients, applying them directly to the soil may offer even greater long-term benefits—increasing available nutrients and more directly supporting the microbes that sustain our plants.

Why I'm Moving Towards a Soil Drench Instead

This article put out by the folks at Washington State University was helpful in explaining that foliar feeding works best for delivering micronutrients (not macronutrients like nitrogen, phosphorous and potassium) when soil pH that is either too acidic or too alkaline keeps nutrients locked up in the soil so plants can't use them. Foliar feeding is a quick fix but...the boost doesn't last long, the nutrients don't go down into the roots and leaves can only take in so much. So that means soil drenches are usually a better choice.

When nutrients are applied directly to the soil, roots take them up with the help of soil microbes. This not only feeds the plant but also nourishes the soil life, building long-term fertility. Soil drenches may take a little longer to show results, but over time they encourage healthier soil and more stable BRIX levels. We'll lean heavily on the soil drench method over foliar feeding this upcoming dahlia season and report back! Our next blog post in this series dives into why plants with higher BRIX values have less pest pressure.