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Compost Tea Guide

Garden Tea Co.‘s Guide to Brewing Actively Aerated Compost and Garden Teas

High quality compost, possessing a full-diversity of biology, is the key to brewing quality compost teas.  Different food sources and techniques used to produce the compost to be used in brewing compost teas will offer differing results.  Food sources added to compost teas can be used in-order to select for the growth of specific target organisms.  Biological assessments or working with ones own microscope are the only means to ensure that the full diversity of biology is present in compost or compost teas.  Ensuring that the proper biology is present in your  compost is necessary to achieve the desired results from brewing compost teas.  Either purchase compost from a source willing to provide biological assessments of their product or have your own compost tested.  Testing your soil or your home produced compost is a useful tool in assessing the life in your soil and the potential benefits of your compost teas.

Biological Testing Labs:
    http://www.soilfoodweb.com (located in Corvallis, OR)

    http://rodaleinstitute.org/shop/soil-lab-test/  (located in Kutztown, PA)
Start with chlorine free water:
The microbes in compost teas are highly sensitive to anti-microbial agents such as preservatives and chlorine in many municipal water sources.
If you have a municipal water source you will want to evaporate as much of the chlorine as possible.  This can be achieved by allowing your water to sit in your brewer without a lid overnight.  You can also aerate your water for 15-20 min prior to use.
Fresh rain water is a great alternative to the tap.

Maintain Constant Temperatures:

  • High temperatures can kill microbes.
  • Low temperatures slow microbial activity.

The microbes that are cultivated in your compost or garden teas stand a higher chance of survival when applied to the soil or a leaf surface that is the same temperature as your tea.  Starting your teas at temperatures as close to the temperature of the soil or leaf zone where the tea is to be applied is your best option.  Place your brewer in a warm shaded spot outdoors or in a basement or garage.
*An aquarium heater can be used to maintain constant temps for more precision brewing and shorter brew times.  Brewing time can be reduced in half when starting with room temperature water.

Customize your teas for the intended plant types, disease, or pest:

  • Bacterial Tea: Use on vegetable crops, lawns, flower and herb gardens, or to control pest outbreaks.
  • All-purpose / Balanced Tea (equal Bacteria to Fungi biomass ratios): Use on vegetable crops, lawns, flower gardens, softwood trees and shrubs, fruit trees, strawberries, berry canes, or to control some pest and pathogen outbreaks.
  • Fungi/ Humus Tea: Use on softwood and hardwood trees, shrubs, berries, lawns, acid loving plants, or to control pathogen outbreaks.  Fungi dominated teas can also be used to enhance the growth of moss.

Brew Times:

  • Bacterial Teas: Brew for 12 - 24 hours to encourage bacterial biomass.
  • All-purpose / Balanced Tea (equal Bacteria to Fungi biomass ratios): Brew for 24 - 36 hours to encourage a more balanced compost tea.
  • Fungi/ Humus Teas: brew for 24 - 48 to encourage a fungal biomass. After 48 hours compost tea begins to express protozoa dominance which mainly feed on bacteria.

Brew times may be reduced by up to half if you are starting with room temperature water.

Ensure a quality extraction:
In brewing compost teas we are attempting to cultivate a rapid growth of the beneficial aerobic organisms present in mature compost into a liquid suspension that can be applied to plants.  This is achieved through active aeration and providing food sources that act as a catalyst feeding the active and dormant organisms into a rapid population growth.
Follow appropriate brew times per compost tea recipe for best results.
Compost may be contained in a filter bag or allowed to float freely throughout the brewing process and filtered at the end of the brew cycle.  The level of filtration for compost teas will depends upon your application method.  If you are applying the compost tea as a soil drench it is not necessary to contain the compost unless your watering vessel has fine holes.  If using a spray applicator it will be necessary to filter your teas prior to filling your sprayer.  We generally filter our teas after the brewing process has been completed.  This method required a second bucket and a filter, but allows for the compost and organisms to float freely throughout the liquid.  Once your brew-time has been reached, filter the finished compost tea into another bucket through a five gallon filter bag.  Lift the bag from the bucket with two hands and gently shake to break the surface tension and allow the tea to drain.  We do not recommend squeezing or pressing the filter bag as you may force sediment thru the mesh which could clod your spray nozzles.  You can also allow the tea to decant for a few minutes and draw off of the top.

Apply teas as soon as possible:
Compost teas are best if used immediately at the end of a brewing cycle.  Be sure to use compost teas within 72 hours of removal from active aeration in your Garden Tea Brewer.
Compost teas can be refrigerated for up to 30 days.  Garden teas such as plant extracts or home brewed fertilizers may keep for longer periods in refrigeration.  Allow teas to slowly return to room temperature and re-activate teas with aeration for 2 or more hours.
Always test the smell of your stored teas.  If they smell foul most likely oxygen levels have been depleted and the compost tea is void of oxygen or anaerobic.  It is best not to apply anaerobic foul smelling teas, instead apply to your compost heap(s) lawns or away from precious plants.     

Mycorrhizae or “fungus” “root” describes the mutually beneficial relationship between a plant and root fungus.  More than 90 percent of plant species in nature form a symbiotic relationship with the beneficial mycorrhizal fungi. Mycorrhizae bond with the roots of a host plant and exchange valuable nutrients and minerals with one another.  Mycorrhizal fungal filaments extend far into the soil and act as an extensions of root systems. Root fungi mine water, minerals and nutrients more efficiently than roots themselves and greatly expand a plants absorption capacity.
Apply mycorrhizal fungi spores at the end of a brew cycle and prior to application (mycorrhizal fungi should be applied as a soil drench):
Mycorrhizal are a bit more fragile than bacteria and should only be added to teas after the brewing process has completed and active aeration has finished. Garden Tea Co.‘s
Application Guide for Compost and Garden Teas

When to apply compost teas:
For best results apply monthly or at more regular intervals throughout the growing season.
In late winter or early spring spray all trees, shrubs, and perennials with fungal dominated compost teas brewed for 36 - 48 hours at least once at the following times:
    - Before the formation of flower / leaf buds.
    - Apply when flower / leaf buds break but have not opened.
Apply a fungal dominated compost tea as a soil drench around trees, shrubs, and perennials monthly or more frequently during the growing season.
Apply at the first sign of any disease or insect infestation.  Fantastic results have been reported with bi-weekly applications as a preventative measure.
Treat disease such as blight and leaf spot with fungi or balanced teas.
Treat insect infestations with a bacterial dominated compost teas.  Severe insect infestations are a sign of a nutritionally deficient plant.  Heavy infestations may need to be treated with an organic pesticide to quickly kill the majority of the infestation or herbicide / fungicide where necessary.  This action should be followed the next day with a bacterial compost tea to ensure the proper biology is present and to help strengthen the sick plant.  This will act as a pro-biotic for your plants and soils.  Repeat this process weekly or as needed.

How much tea do I apply?
Undiluted compost and garden teas work great; however, they can be diluted at any ratio up to 15:1.  A 15:1 ratio is easily achieved by using a hose siphon to apply filtered teas.)
You can never apply too much compost tea.
Repeated applications of compost teas will only help to increase the diversity and populations of beneficial microbes.
Compost teas can be applied as a soil drench or root dip when transplanting.  Compost and garden teas can also be sprayed directly onto a leaf surfaces or diluted with a hose siphon for easy application.
As a root drench apply 5-10 gallons (full strength) or diluted up to 15:1 per 1/4 acre.
As a foliar spray apply 5-10 gallons per acre.

How To Apply Compost Teas:
It is best to apply compost teas when plants and soil are moist.  Early mornings with humid conditions help to ensure that beneficial organisms cultivated make good contact with leaf and soil surfaces and stay and remain active.
Soil Drench (soil and root inoculant)
It is best to apply when the soil is moist early in the morning or late in the evening.
Apply at regular watering intervals for outstanding results.
Apply from the base of plant as far out as the plants drip line or root mass.
Use plastic watering vessels as bacteria can eat-away at the zinc in metal.

Foliar Spray (applied to leaf surface as an inoculant)
Use a clean hand pump or pressurized sprayer. It should be noted that not all sprayers are built alike.  Some allow for larger particles to pass through the spray nozzle(s) with ease. Diaphragm sprayers work great for this type of application. We have experienced good results with the Solo brand backpack sprayers. If using a Gilmore or equivalent brand 2 gallon type of handheld sprayers we suggest upgrading the sprayer wand with a more durable and versatile sprayer wand.
Do not exceed 70 psi (slow dispersion is better). Most hand pump and diaphragm sprayers will not exceed 70 psi.
Spray pattern should be wide and gentle with no hard splattering
Teas should cover 70% of the leaf surface for maximum effectiveness and remain moist for 15 minutes or longer.
Avoid spraying open flowers and fuzzy-leafed plants, like African violets.
In dry conditions, spray teas early in the morning or in the evening to allow the organisms in the tea to remain moist and active after application.

What is the best time of day to apply compost and garden teas?
Ultraviolet rays from the Sun can kill microbes so it is best to apply teas before 10:00am or after 6:00pm regardless of cloud cover and the time of year.
Avoid spraying teas in heavy rain or prior to a rainfall.  
Moist and misty mornings or after rain is an excellent time to apply compost teas.

Apply teas as soon as possible:
Compost teas are alive and as oxygen levels in the tea decreases so will the populations of the active aerobic organisms you have cultivated.  Teas are best if used immediately after removal from the highly aerobic environment of your Garden Tea Brewer.  It is best to use all your tea within 72 hours of removal from your Garden Tea Brewer.
If your tea sits too long and smells foul then discard in a compost heap.
You can never apply too much compost tea.
Undiluted AACT’s work great; however, teas can be diluted at any ratio up to 15:1. This 15:1 ratio is easily achieved by using a hose siphon and a watering wand.
Repeated applications of compost teas will only help to increase the diversity and populations of beneficial microbes.
Compost teas can be applied as a soil drench or root dip when transplanting.  Compost and garden teas can also be sprayed directly onto a leaf surfaces or diluted with a hose siphon for easy application
Clean your brewer, watering vessels, and/ or spray applicators immediately after each batch of tea or application: (remove all tea and or bio-slime residue as soon as possible)
Thoroughly clean brewer bucket, hose, and air diffuser and sprayer after each batch of tea.
Use dish soap and a scrub brush to clean all of the residue known as bio-slime from all of your components before storing.
The air-diffuser included with our Garden Tea Brewer can be safely cleaned in the dishwasher.
Hydrogen Peroxide can also be used to sanitize your equipment.  Hydrogen Peroxide will kill many microbes and using a it with dish soap and warm water works as a thorough cleanser.
Baking soda can be used as an abrasive cleanser.
“No Rinse Cleansers”, such as One Step, used to sanitize bottles and equipment for the home brewing of beer and making wine works well to sanitize your equipment.