Gardening Advice and Macronutrient Ratios

I was listening to a gardening program on the radio the other day, and the expert on the show was recommending even N-P-K plant foods to everybody. 10-10-10 for some, 20-20-20 for others. Out of curiosity I checked the N-P-K on Advanced Nutrients Micro and Grow, the products that we use to feed our lettuce.

Micro turned out to be 5-0-1, while Grow’s N-P-K is 2-1-6. For non-gardeners, this measurement indicates the percentage of Nitrogen, Phosphorus, and Potassium in your fertilizer. So if I factor in the N-P-K of SensiCal Mg Mix Grow—2-0-0), which is a calcium supplement that we regularly feed our lettuce, our combined N-P-K comes out to 9-1-7. A far cry from what this so-called expert on the radio was talking about.

To educate myself, I called the Advanced Nutrients technical help line. I reached a very knowledgeable man, who assured me that recommending an even N-P-K ratio to the general public is a cop-out. If you do genetic specific testing on the vegetables you grow, you’ll find that each of them has a slightly different need for these basic macro-nutrients.

He went on to say that Micro and Grow are designed to cover a wide array of flowers, fruits, and vegetables. “What if the N-P-K ratio isn’t exactly what my lettuce crop needs?” I asked. “Don’t worry,” he said, “plants eat only what they need. Your combined N-P-K is perfectly adequate to meet the basic needs of any vegetable you may decide to grow.”

He added that if I were growing tomatoes, of course, I would have to add the N-P-K of Bloom, which is 0-5-4, which would bring my combined ratio to 9-6-11. “There is a lot of vagary, where N-P-K ratios are concerned,” was his final comment on this topic.

In terms of the mixing ratio of the Advanced Nutrients 3-part, he said that 1:1:1 works best, although some growers might want to follow the traditional 3:2:1 then 1:2:3 regimen. Whichever proportions you select, Micro goes into the mixing tank or reservoir first, mix it well and wait until it dissolves, then add Grow and Bloom, in that order. Never mix the 3 parts in their concentrated form.

I reminded him that I wasn’t using Bloom, since I didn’t want my lettuce to start flowering and go to seed. He said that’s fine, the 1:1 ratio would still apply.

When I mentioned that my partner and I were using SensiCal regularly in our reservoir, he said that it could also be used at half the strength as a foliar spray. However, don’t spray for a few weeks before harvest, since this process would leave a chemical residue on the lettuce leaves. I said I would rather just mix it in the Nutrient Pond, and stop using it near the harvest end of the pond for a few weeks before harvest.

SensiCal has been designed to provide the proper synergestic balance of Calcium, Magnesium, and the other minerals it contains, which include Boron, Cobalt, Copper, Iron, Molybdenum, and Zinc.