Help with quantities to mix in a hose sprayer for fertilizing

[Henderson]

The last 2 years I've been fertilizing my outdoor planters and hanging baskets weekly with a 2 gal watering can and mixing the solutions, which takes at least 6 can fulls and lugging it around, probably more this year as I've added a few more planters, and it takes quite awhile to do. So you can see why I'd love to be able to use a hose end sprayer with the mixture, but I want to be sure my thinking is right about how to do the mix so I don't kill the plants. I've tried posting at gardening forums but I'm not getting any help there, so here I am.

The lowest setting on the sprayer is 1 teaspoon per gallon mix. I have 2 solutions I want to combine and do at once. One solution requires 1/2 teaspoon per gallon, the other 1/4 teaspoon per gallon.

So my thinking is to dilute the 2 mixtures and combine them in the container to use in the sprayer. The solution needing 1/2 teaspoon per gallon would be diluted 2 parts fertilizer and 2 parts water. The one needing 1/4 teaspoon per gallon would be diluted 1 part fertilizer and 3 parts water. Mix both in the container, then set the sprayer to 2 teaspoons per gallon flow.

Is my logic and math right about this? I don't want to burn the plants and kill them. Nor do I want to dilute the mix too much so that it's ineffective and I'll just be wasting my time and product. I originally thought the sprayer should be set to 1 teaspoon per gallon, but the solutions are actually being diluted twice by the fact that there are 2 of them mixed in the container, correct?

Thanks for any advice and help.

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[Dr.Peterson]

The last 2 years I've been fertilizing my outdoor planters and hanging baskets weekly with a 2 gal watering can and mixing the solutions, which takes at least 6 can fulls and lugging it around, probably more this year as I've added a few more planters, and it takes quite awhile to do. So you can see why I'd love to be able to use a hose end sprayer with the mixture, but I want to be sure my thinking is right about how to do the mix so I don't kill the plants. I've tried posting at gardening forums but I'm not getting any help there, so here I am.

The lowest setting on the sprayer is 1 teaspoon per gallon mix. I have 2 solutions I want to combine and do at once. One solution requires 1/2 teaspoon per gallon, the other 1/4 teaspoon per gallon.

So my thinking is to dilute the 2 mixtures and combine them in the container to use in the sprayer. The solution needing 1/2 teaspoon per gallon would be diluted 2 parts fertilizer and 2 parts water. The one needing 1/4 teaspoon per gallon would be diluted 1 part fertilizer and 3 parts water. Mix both in the container, then set the sprayer to 2 teaspoons per gallon flow.

Is my logic and math right about this? I don't want to burn the plants and kill them. Nor do I want to dilute the mix too much so that it's ineffective and I'll just be wasting my time and product. I originally thought the sprayer should be set to 1 teaspoon per gallon, but the solutions are actually being diluted twice by the fact that there are 2 of them mixed in the container, correct?
​

I think I'd want the result to be the same as if you separately diluted each substance in its own gallon of water. So in two gallons of water, you want 1/2 tsp of one, and 1/4 tsp of the other. That means you want to put, in each (one) gallon, 1/4 tsp of the first and 1/8 tsp of the second. I'm not sure this is right, but it seems to be the safe way to go. (This is more than just a math question.)

Now, this amount has to be in the one tsp that the sprayer adds to each gallon of water. So each unit of diluted solution will consist of 1/4 (2/8) unit of A, 1/8 unit of B, and the rest (5/8 unit) water. So mix them 2:1:5 (A:B:water). Then you can spray at 1 tsp/gal.

Does that make sense? Note that my thinking is based on focusing on the result, which can be checked, rather than just on the procedure.

 

[Henderson]

Now, this amount has to be in the one tsp that the sprayer adds to each gallon of water. So each unit of diluted solution will consist of 1/4 (2/8) unit of A, 1/8 unit of B, and the rest (5/8 unit) water. So mix them 2:1:5 (A:B:water). Then you can spray at 1 tsp/gal.

Does that make sense? Note that my thinking is based on focusing on the result, which can be checked, rather than just on the procedure.

Yes, it makes sense and that was my original way of thinking as well. Maybe I started to overthink everything and that's when I thought it's diluted again in half by the presence of the 2nd solution. When mixing into that small container on the sprayer, it seemed like it would make a difference compared to hand mixing the solutions in a 2 gallon water can, where it wouldn't make a difference at all.

But when I used the 2 teaspoon per gallon setting, it seemed to eat up the solution much faster than expected, so I'm thinking I'm going to set it to the 1 teaspoon per gallon rate. I used half my container solutions into the sprayer and at that rate, and I don't think it will last half the summer of weekly fertilizing. Last season mixing it by hand in the 2 gallon water can, I only used half of the solutions for the entire summer.

Btw, I also wrote to the company that makes the sprayer, there are a few videos out on YouTube about how to mix solutions in this particular sprayer and thought they should know. But I got a terse reply saying they're not chemists :lol: and wouldn't recommend mixing 2 solutions at once. But it has to be doable and get the right quantities.

But for now, I'm going with your recommendation and setting it back down to my original thoughts of 1 teaspoon per gallon flow. The proportions I used were exactly 2:1:5 (A:B:water) as you also came up with, I just split it up into each solution's own formula of 2:2 and 1:3 (AB:water) when I explained it above, and it works out the same.

Thank you for the help with this, the part about using 1 or 2 teaspoons per gallon flow was making my brain hurt!