@Underdog
Hi Mark,
Yes, you can use it. Yes, it is concentrated. That means you should use less per gallon. So the first question is how strong do want your fertilizer solution?
For tomatoes and vegetables in the ground where we are pushing absolute rapid growth, 1000 ppm as Nitrogen is "label strength" for most Vegetable garden fertilizer dosages. This I believe is TOO STRONG for bonsai.
Most bonsai fertilizer seems to end up in the 72 to 200 ppm concentration as N range. This is good for general fertilizing. This is where fertilizer is applied weekly or every 2 weeks.
If you are one of the "continuous feeding" persons, where you are fertilizing every watering, somewhere around 40 to 72 ppm as Nitrogen might be right. You don't want overly rapid growth.
One other thing to note, this fertilizer has no Phosphorous, P, in the formula. Plants hang on to phosphorous, it is not flushed out of plant tissues to any degree by watering. So it would be perfectly acceptable to water with the lawn fertilizer once every week for 3 weeks, then hit the trees with a fertilizer that contains phosphorous. Now trees really do not need a huge amount of phosphorous. A fertilizer balanced for the needs of the tree would actually be 12-0.8-4-12-4-2 being Nitrogen-Phosphorous at less than one - Potassium - Calcium - Magnesium-Sulfur. The list of nutrients goes on, but the rest are "micro-nutrients" in that they are generally less than 1% on this scale.
So what is the right dose?
Note 1 teaspoon is roughly 5 milliliters, and is based on the assumption fertilizers weight roughly 1.5 kilograms per liter volume. This is only an approximation, but works out pretty close, give or take 10%.
1/2 teaspoon of 29-0-4 to one gallon = 191 ppm as N, 22 as K (potassium) and the TDS added will be 213 ppm tds.
1/4 teaspoon of 29-0-4 diluted to one gallon will yield a solution that is 96 ppm as Nitrogen, zero P, Potassium = 11 ppm and the tds added to the water will be 107 ppm tds.
The half teaspoon and the quarter teaspoon doses seem to be in the "acceptable range" for bonsai
One teaspoon of 29-0-3 diluted to one gallon = 383 ppm as N, 44 ppm as K and the solution adds 427 ppm as TDS
One tablespoon, (3 teaspoons or 15ml) of 29-0-4 per gallon of water = 1148 ppm as N, 131 ppm as K, and adds a total of 1279 ppm as TDS.
You can see the 1 tablespoon strength, (15 ml) per gallon strength is in the acceptable for tomatoes and peppers, but "too hot" for growing bonsai slowly with short internodes.
But if you understand how to dilute the fertilizer, you can use any number configuration.
How did I do the calculations, I cheated of course. I used the "fertilizer calculator" available on First Ray's website. You can use this to model any fertilizer you want.
A simple Fertilizer TDS Calculator to help you truly manage your feeding regimen.
firstrays.com