I use the stuff routinely for veggies. That first number is big because, well, there is a lot of nitrogen in it. You use too much, and you will burn the plants. Actually MG fertilizer is mostly urea, which decomposes in soil into NH3, which is nitrified. Now, be aware that NH3 is a gas that floats away readily, so you really want that decomposition to happen inside the soil where the gas can get trapped, and not on the surface. Soak, don't sprinkle, the liquid.

My soil has loads of P and K, so I just use it for a N boost. Adding P and K to my soil would be useless. In fact, slow release lawn fertilizer works for me too. Pure ammonium nitrate. But it's not as convenient, and dosing is more chancy. I'd like to find an economical source of urea, which I could dissolve in water, but haven't located that yet.

Many use it and yes, your math is basically correct. But using a quart container would seem to be the issue since you might be able to water some small house plants sufficiently with only a quart of mix, it isn't nearly enough water ot fertilizer for most vegetables in containers (assuming properly large enough containers). Think in terms of gallons, not quarts for them.

Dave

Also, be advised that MG is not a slow-release fertilizer. You get BOOM! lots of nitrogen, and that nitrogen will leach out. So if you really want to use it with maximium effectiveness, you'll be applying every few weeks and, as Dave says, you're applying it many quarts at a time. So all in all, you're really putting out plenty of stuff.

The quart bottle is just for the seed trays and smaller transition pots in my grow rack, where it's hard to get the gallon water can into. Plus it's got the gentle drip/spray nozzle so it doesn't wash out the smaller tender plants. When they get bigger, I use the big water can.

Thanks for all the responses. I figured it must be correct, but I'm just surprised it really takes such a tiny amount, and wanted to confirm I wasn't off-base somehow. This stuff must really be super concentrated. I know it's not slow-release (both pros and cons to that one), so I do try to add some to the water can/bottle every 2 weeks or so. Although I really need to get better at actually keeping track.

Don't fertilize new seedlings at all. They won't need it until they are photosynthesizing, so the rule of thumb is not until they have some true leaves.

Seedlings under lamps are going to be photosynthesizing like crazy. Full leaves will appear within days of germination. That's correct, I wouldn't fertilize ungerminated or barely germinated seeds. But seedlings, yes. Half or quarter strength.

Yeah, I made that mistake last year before finding out later not to fertilize until after true leaves appear. But I still have them in seed trays at that point until they get somewhat bigger.

I should say that you don't need to wait for true leaves. Cotyledons, left to their own devices, will start to photosynthesize as the seed nutrients run out.