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The unit comes with several tip options. We like the brass sprayer (beware of lead, though).

New Toy: Compost Tea Sprayer

Last year after taking Dr. Elaine Ingham’s Soil Food Web intensive, I ran out and purchased a piston-pump sprayer to take my compost tea to the next level. Compost tea is great for plant roots and soil health, but it also makes a great foliar feed (using said compost tea sprayer). Plants respond with a jump in growth, and a reduction in surface- or soil-born fungal infestations.

Since tomato season is here, and blight is never far behind here in coastal Los Angeles, we’re acting preemptively with compost tea to keep it at bay. After all, with the right balance of fungi and bacteria, you can combat almost any plant disease or pest. It all starts with good quality compost tea, brewed at home or obtained from a professional.

Backpack sprayers are easy to carry and use.
Backpack sprayers are easy to carry and use.

We chose the Solo 4-gallon piston-pump backpack sprayer that was recommended among colleagues during the Soil Food Web course. It took a few minutes to assemble and we we’re off and running.

Solo is made in the USA and sold at many hardware stores.
Solo is made in the USA and sold at many hardware stores.

In order to prevent clogging, we adjusted our compost tea recipe to put the bulk of the ingredients in the tea bag instead of in the bucket. So we used Soil Revive (instead of fish hydrolysate) in the bucket, and soluble kelp, alfalfa meal, insect frass, humus (humic acids) and of course, compost in the tea bag. We brewed for 24 hours with aeration. Now we’re ready to go.

The unit comes with several tip options. We like the brass sprayer (beware of lead, though).
The unit comes with several tip options. We like the brass sprayer (beware of lead, though).

The sprayer nozzle is the most important part of a compost tea sprayer, because it has to have at least a 400 micrometer opening to allow microbes through. The standard spray nozzle with this backpack is sufficient.

Coat tomato leaves top and bottom to prevent infestation and promote vigorous growth.
Coat tomato leaves top and bottom to prevent infestation and promote vigorous growth.

It’s ideal to spray on a non-windy day, when temperatures are mild. Hot temps can fry wet leaves and kill your microbes. We also accompanied the foliar spray with a soil drench of the same compost tea that we diluted with rain water for added benefit (remember, chlorine and chloramine kill microbes). A watering can with a rose that has larger holes is best.

The pump handle can be installed for left or right hand use.
The pump handle can be installed for left or right hand use.

We sprayed down all our veggies and fruit trees, then added a soil drench to all beds to inoculate our existing soil with a fresh batch of microbes. Be sure to clean all your equipment immediately following use. Residues breed anaerobic bacteria, which is bad for plants and soil.

In a week or so, we should see the results of the application. In the past, with just a soil drench, we’ve seen plants jump and bloom. We’ll report back our findings on the changes we see this season because of the foliar application.

This Post Has 5 Comments

  1. Jeff

    Gardener Nerd,

    It is great you pointed out spray nozzle that comes with Solo sprayer is not proper for microbial application.
    However, you did not specify what nozzle to get and where, would you mind sharing that information please?

    1. Christy

      Hi Jeff, I didn’t say that. “The standard spray nozzle with this backpack is sufficient.”

  2. Malte

    Hey,
    maybe I am overthinking this but I am searching for a good spray nozzle for my tea sprayer right now.
    The one I have right now looks like yours from the outside and has a small plastic diffuser inside which swirls the liquid into a mist and then pushes it out against the metal. I am thinking the angle between the spiral inside and the metal part is almost 90° and might be too much force to reliably get living microbes through.
    Do you have any experience with different nozzle types?
    Greetings from Germany
    Malte

    1. Christy

      Unfortunately I don’t have much experience on that subject. But – I remember doing some research when I wrote this article and as long as your mesh is 400-600 microns, those microbes are getting through so I wouldn’t worry about it too much.

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