Foliar Sprays for Market Gardens

We’ve come to the end of our series about market gardens. So far we’ve covered four steps:

1. Creating the right physical environment
2. Adding biology that has been lost
3. Feeding biology with mulch or cover crops
4. Providing balanced mineral nutrition

If you’ve followed these steps, your soils will be on track to develop thriving biology that can provide most, if not all, of the nutrition needed to grow vibrantly healthy crops. However, the process of building soil to such a state of health can take time. So how can we speed that process along, and how can we provide the nutrients that our crops need in the meantime?

Fundamentally, the way to maximize our farm’s performance is to maximize photosynthesis. Plants that are photosynthesizing better produce excess sugars, which they feed out through their roots to the soil biology. The most effective way to increase plant photosynthesis is by providing the minerals they need to build chlorophyll molecules and the other important components of their photosynthetic engine.

One of the best ways to quickly get these nutrients into plants is through foliar sprays. Foliar sprays are nutrient applications directly onto the leaves of plants. Living plant tissue absorbs those nutrients, and the plant transports them to where it needs them. Foliar sprays have many advantages:

• Nutrients in the soil can become tied up and inaccessible to plants.
• Foliar-applied nutrients are available to plants almost immediately. It may take months or even longer for soil-applied nutrients to get into the plant.
• Foliars can be applied throughout the growing season and their effects can be monitored and measured.

Synergistic Stacks

We have found that the most effective foliars (and other applications like fertigation) are built on the principle of synergistic stacks. A synergistic stack includes many ingredients, each enhancing the functions of the others, and attains an effect greater than the sum of its parts.

A synergistic stack of ingredients in a foliar spray could be

1. compost tea
2. microbial inoculant
3. seaweed
4. plant nutrients
5. trace minerals

Market Gardens Foliar Formula

Here’s a general purpose recipe for a foliar spray that we have been recommending to market gardeners:

• 4 parts MacroPak™
• 1 part MicroPak™
• EITHER: 4 parts Accelerate™ (if the plants are fruiting) OR: 4 parts SeaStim™ (if they’re not fruiting).
• Micro5000™ as a biological inoculant.

(find more detailed information on application rates here)

To this you could add other ingredients you have on hand, such as compost tea or biostimulants. Spray it onto your plants every 2 weeks. Foliars are more effective when they stay liquid on the leaf surface to give the plant as long as possible to absorb them, so apply them in the evening.

You could alter the recipe based on what Critical Point of Influence your plants are in. The nice thing about this recipe is it provides a broad range of nutrients that can assist a range of plants at many different stages of growth, and so is practical for market garden settings with a diversity of crops.

Water Quality

An important note about foliar sprays is that water quality can really impact their efficacy. Chlorine in municipal water or high levels of bicarbonates in well water can affect calcium availability and the viability of AEA products.

Generally speaking, rainwater is the best water to use for foliar sprays. If you are using well water or municipal water, it’s a must to get your water tested to be aware of any potential issues. If you find high levels of chlorine or bicarbonates, here are some ways to correct them:

Bicarbonates:

• The lower, the better. Below 60ppm is ideal.
• Concentrations above 120ppm should be filtered by reverse osmosis, or replaced by another water source such as rainwater.
• Lowering the pH to 6.5 neutralizes about half the bicarbonate in the water. Conventional growers can inject sulfuric acid or phosphoric acid to lower pH; organic growers can use sulfur burners.

Chlorine

• HumaCarb™ is a very good chlorine binder. If being used to remediate chlorine only, I would add HumaCarb at a rate of 0.25% of the solution, or 1 qt per hundred gallons (~1/4 cup per 5 gallons).
• You can let small amounts of chlorinated water sit for 24 hours. Much of the chlorine will evaporate.

Conclusion

These steps should add some key pieces to your toolkit as a market gardener. Hopefully they will help you rapidly improve your soil and grow quality produce.

I wish you many bountiful harvests!