First Ascocentrum hybrid seedling spike

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At the end of July I received an order of Vanda seedlings from Motes, including #1944, Vanda christensoniana x ampullacea (or Ascocentrum christensonianum x ampullaceum depending on your orientation.) I put them into vase culture.

Last night I sprayed the roots with fertilizer solution as usual. This morning I went to pour fertilizer into all the vases for a regular all-day soak and noticed a spike forming that wasn't there last night.

They are in a sunroom with 4-6 hours of sun through the window daily. Temperatures vary from the 80s F / upper 20s C by day to minimum 60F / 15C at night. Humidity is 50%-60% by day and 70%+ at night.

I try to water the plants at least once per day. Most of the time this is a spray bottle to the roots, which I try to do in the morning. But if I don't have time, I'll do it at night, before the room cools too much. I try to fill the vases for a 12-hour soak at least once per week, and it seems 3 times per week is even better.

I'm using 1 teaspoon / 5ml powder per gallon / 3.78 liters of MSU rain formulation 13-3-15-8Ca-2Mg in rain water for almost all soaking and spraying. This works out to about 175ppm nitrogen. Once a month the long soak is rain water with 2 teaspoons KelpMax per gallon. I got the MSU and KelpMax from First Rays. There are always lots of new root nubbins formed after the long kelp soak.

[wintergirl]

Happy for your spike I just started using the MSU fertilizer for r/o water today and noticed your mixture is twice the mixture recommended on the bottle.

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Originally Posted by wintergirl

Happy for your spike I just started using the MSU fertilizer for r/o water today and noticed your mixture is twice the mixture recommended on the bottle.

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.

[wintergirl]

Is that measurement of the growth band different in smaller vanda types such as your as compared to a larger vanda? Just curious because I am an under fertilizer and my vandas are growing well.

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He doesn't make a growth band distinction between seedlings and adults in the books. In fact, he writes seedlings need even more fertilizer than adults.

Thinking about it as a plant, it shouldn't matter. Elongation is produced by cell division, then engorgement with water. The rate of apical meristem cell division shouldn't vary much among healthy plants of different ages in similar circumstances. The size of the meristem might vary. Smaller Vandas would be expected to have smaller leaves in cross-sectional area, but they should elongate at about the same rate. When I upped my fertilizer from 40ppm to 100ppm, and again from 100ppm to 175ppm, I noticed almost immediate increases in growth rate. However, I have also been leaving them to soak for increasingly longer periods of time. This would increase their exposure to fertilizer and allow them to absorb more.

[wintergirl]

It will be interesting to see how your care of your vanda advances or changes over time.

[vlhart]

Wow--I had no idea how much I was under-fertilizing my Vandas. Thanks for this info!

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Update: It might be a vegetative offset, not a spike. I also though the Darwinara/Vanda Deep Blue Seas I bought in flower from First Rays in early summer 2015 might be pushing two spikes, but those also look like vegetative offsets.

I wrote Martin Motes to ask about fertilizing Vandas. He said since the Michigan State study came out, they have been fertilizing less than he recommended in his books, but always with the aim of having a centimeter-wide band of light green new growth on emerging leaves. He also told me that if any of my plants have any red tinge I should give them more magnesium via epsom salts dissolved in the water. People used to think red coloring was normal on Vandas, especially Ascocentrum and their hybrids, but Dr. Motes said this is magnesium deficiency, especially if more prominent in cooler weather. I didn't ask how much to use, since this would vary a lot with the local water. I also asked about what water to use. He uses Florida well water on his plants when it hasn't rained, or for fertilizing. His well water is extremely high in dissolved solids and has a high pH, similar to mine. He said rain would be better, but Vandas would do OK with my tap water, similar to his well water.

Then I got to thinking about calcium supplementation - it seems silly for me to buy calcium fertilizers when my tap water has so much in it:

City of Phoenix Water Quality Report

So I'm going to use a quarter tap water to three quarters rain on my orchids and see how things go. Right now I have plenty of stored rain, but you never know when it will rain again.

I was also interested to learn the pH of my water is a little lower than it has been in the past. In previous water quality reports Phoenix varied from pH 7.5-8.5, and now it's down to 7-8.

I'm also watering my Vandas more and more and the plants are much happier for it. My growing area humidity varies from 50% in the daytime to 70% at night, which is lower than ideal for Vandas, so they probably need more water than they would in south Florida.

I soak the Vanda's roots in fertilizer solution for 10-12 hours every 2-4 days if it's sunny and their growing room is warm. If I don't have time to put them to soak I try to spray the roots at least twice every day, though I don't do that on cloudy, cold days.

I now have much better root growth on most Vandas, and new roots are much thicker than old roots. Ascocentrums and hybrids are not making as great roots like the Vandas are, but they are making leaves.

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It's a vegetative offset, not a spike. That means more flowers in the future!

[Miri the Wildmage]

Sorry, by 'the pale green band at the base of the leaves' I'm not quite sure which bit you mean! I'm sure it's just me, since other people all seem to understand you, but do you think you could post a picture showing what you mean? Possibly it could just be that my vanda is so underfertilised this band isn't there at all, but...