Rob's "Recipe" for Peat (tannic) Tea
This solution can be useful in correcting pH and nutrient problems which mainly occur in plants that have been in the same pot for a long time and are showing signs of nutrient deficiencies (pale/incorrect color.) Peat tea can often increase coloration in red-pigmented plants and is very helpful in maintaining acid conditions in media with a lot of drainage materials, such as perlite, sand or other mineral aggregates. To avoid aggravating potentially salt/mineral laden media, thoroughly rinse out the media before applying peat tea.
This recipe is slightly modified from the original article appearing in the Carnivorous Plant Newsletter.
1. In a large, stainless steel or enameled container: add 2 gallons pure water (distilled, reverse-osmosis,etc.), 3/4 gallon new, unleached peat moss-tamped slightly,and a ball of long-fiber sphagnum (dead,dry) about the size of a grapefruit, compressed slightly. You can also substitute many acidic humus sources for the sphagnum, including leaf humus (partially decayed) from pine, oak, hemlock (Tsuga) and mixed forests. These will tend to float; stir them down with a stick, I use bamboo, until the ingredients are saturated.
2. Add one more gallon of pure water.Stir.
3. Bring this mixture to a high temperature. There are many soil chemists who prefer to keep the temperature at 160-170°F, due to the perishable nature of some soil enzymes, but I bring the mixture to a low simmer for 20-30 minutes to nearly sterilize the concentrate. This mix will require occaisional stirring to prevent boil over and is best done on a camp stove outside!
4. After 30 minutes, remove from heat and wait about 5 minutes, for some settling and cooling.
5. This is the tricky part; be careful as the hot concentrate is not easy to handle. You may wish to cover the liquid and let it cool before straining. I'm familiar with handling it and prefer to strain it hot into containers so it will keep better (about 2-3 weeks in a covered milk jug.)
Stretch a nylon stocking over a clean, large funnel or galvanized watering can, leaving some slack for the solids. Secure this if needed so it won't slip. Slowly pour the concentrate to ONE SIDE of the stocking to strain it. If you pour too quickly, the solids will plug the nylon and cap the receptacle, spilling the brew over the top! You can use the stirring stick to hold back the larger chunks while pouring. Avoid skin contact as this will add bacteria, possibly burn you (if hot) and decrease the storage life of the concentrate. With experience, this filtering will get easier as you adapt your technique to your equipment.
6. Once cool, add about 1 1/2 cups of this concentrate to a gallon of pure water and aerate the diluted "peat tea" by vigorously shaking in a partially filled jug. For those of you with test equipment, I standardize this tea by adding either concentrate or water to achieve a pH of 4.5-5.4 and a conductivity of about 18-22 microsiemens. The above dilution ratio should get you close enough for most applications, so exact meter readings aren't usually needed. The solution should be dark tea colored and can be used to drench the soil of the plants you wish to treat. Store the concentrate in clean, covered plastic milk jugs. Use diluted (ready to use) tea within a few days, or it will start to grow microbes (mostly harmless water molds.) I do not recommend using the concentrate without dilution.
I apply this once every month or so, mostly to plants that have been in the same pot for years. Be sure to leach the soil between applications or evaporation can concentrate further the chemicals in the soil. I haven't tested this stuff enough on Dionaea, but since flytraps like to be repotted every year in fresh peat, I believe they would benefit from the tea, which can lower the pH in older media. Pinguicula planifolia does benefit from this tea, as do most Nepenthes.
This recipe makes about 1 1/2 -2 gallons of concentrate, which is a lot for most people; you can divide the recipe in half or quarters, as needed.
Many plants can take, may benefit from a stronger solution, but I wouldn't use over 3 cups concentrate per gallon of water unless you have experimented and found it safe for your application.
I hope some will find this information useful. After the article in The Carnivorous Plant Newsletter was published, I received several letters and phone calls from growers who had "problem plants" perk up a few weeks after using this tea, most likely due to pH improvement. Some created their own recipes and techniques. One grower uses "blackwater" which is naturally formed tannic water found in some wetlands. The basic technique has had many successes, but if your plants are growing fine, I wouldn't bother; don't fix what isn't broken!
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