First Ascocentrum hybrid seedling spike

[orkkid]

Originally Posted by estación seca

Yes indeed.

I have Martin Mote's book Florida Vanda Growing Month by Month. It's... ummm... here on my desk somewhere under this neat pile of paper.... I bought it through the Motes Orchids Web site, and I strongly recommend it to anybody who wants to grow Vandas, even if you don't live in Florida.

Well, on the bookshelf is also Mote's Vandas: Their Botany, History and Culture. This is an older book which I found used from Amazon.

He writes Vandas grow constantly if light, temperature and water are correct. They grow much faster and bloom better if fertilizer is correct. They need much more fertilizer than any other orchids. He says to fertilize to the point the new pale green growing band at the base of the developing leaves is a centimeter long. If not that long, they need more nitrogen. If the band reaches 2cm long, that is too much fertilizer.

He writes that, for Vandas growing in warm and bright conditions, he fertilizes at every 5th watering. He waters at least once daily, twice during the hot dry season in Florida. So he fertilizes every 3-5 days.

When he fertilizes, he uses 20-20-20 at the rate of two tablespoons / 30ml of powder per gallon / 3.78 liters of water, or 1 gram per 2 liters. Yes! Two Tablespoons. That yields 1,600ppm of nitrogen, according to the calculator on the First Rays Web site.

The MSU nitrogen number is 13; to get to 1,600ppm you would need 9.3 teaspoons per gallon, or 3 Tablespoons plus one teaspoon. This volume of powder is about 12ml per liter.

He does say that with suboptimal light or temperatures, less fertilizer is needed. But he says always to judge fertilizer by the width of the pale green band at the bases of the developing leaves.

That is a large osmotic load for a plant. He uses hard, highly mineralized Florida well water in between, and to dilute his fertilizer. I guess strong Vandas aren't too concerned with high osmotic loads. Motes wins awards.

I have warm and bright conditions all year. I fertilize at almost every watering, and Motes fertilizes at every fifth watering, so I should be using about 1600/5 = 320ppm or 1.8 teaspoons per gallon / 2.4ml per liter of MSU powder.

I have noticed my growth bands are less than a centimeter wide, so it's time to binge.

In the Month by Month book he also discusses magnesium, which is not mentioned in the older book. If your fertilizer doesn't have it, you need to alternate Epsom salts solutions with fertilizer. The book is in this neat pile of paper that I don't want to disturb just now so I will have to write about that later. The MSU from First Rays has magnesium so I haven't bothered with the Epsom salts.

Do you still follow this mantra? It seems in line with what I have heard