Dendrobium Seedlings just not growing

[greyblackfish]

Hi dendrobium growers,

I've got 3 dendrobium phalaenopsis seedlings that I've had for 2 months. My other seedlings (oncidiums, cattleya, phalaenopsis) are growing like crazy in these hot summer months, my dens aren't growing at all. They get a lot of light in the morning and evening and in mid day they get a weaker grow light.

The little bulbous one is the New Hope Mini which isn't growing but doesn't have any bad history in these two months. I've kept them in sphagnum moss and keep them hydrated. They just don't grow.

The other two have been kind of the experiment ones. They started out in bark mix combined with a bit of moss. They wouldn't stay hydrated at all and I have recently repotted them in all moss. The sad one with the single leaf arrived with a pretty cane but the cane and leaves dried up very quickly and I cut it off. Yes I know that I'm not supposed to cut off canes but I was worried about disease and it was dried up. Anyway the surviving cane has hung on. When I repotted, I saw no growth at all.

Are they simply in dormant stage even when it's growing time? Please help

[estación seca]

The one is unfortunately dead.

If you let these tiny seedlings dry out for more than a day, they are set back badly. It takes a long time to begin growing again when that happens. The nobile types are even more susceptible to drying out than the phal types. I keep both types in soggy wet sphagnum most of the time. They won't rot when it's warm.

I suggest you not repot Olympic Orchid Den. seedlings, or seedling-sized mericlones, until they outgrow the pot. The sphagnum arrives fresh, and they are set back badly by premature repotting.

I would not use slotted pots for Den. seedlings. They dry out too rapidly.

Water them before the moss goes dry. I try to keep them soggy wet. If yours have damaged roots i would let them dry somewhat and not keep them soggy until they make new roots/growth.

Fertilize at least weekly. As long as it's warm and humidity is reasonable they will push new growths one after another, each larger than the previous.

This is a Den. Triple Fantasy mericlone from Olympic Orchids in sphagnum in the original 2" / 5cm pot. I got it about a year ago. The moss is old. The newest growth is on the right. I could repot, or I could wait until the growth after this. I've tried rerotating it but it doesn't work on my phone.

[greyblackfish]

For starters, I'm going to take care of that one until it dries up into a husk

Yeah I've realized I should have kept them in the pot they arrived in. The moss was definitely fresh but I thought they would dry out too fast. Well.. that's why I'm a novice. I'm sure I'll order small seedlings again and not rush to repot so I can do it right next time. The other two came unpotted from another seller.

I fertilize every other week. I will try every week instead. That might be the key since my mature denphal also has not grown bigger canes and I've had it for two years. If you'll see the attachment, this picture is from a month ago and the new cane is bigger but still not as tall as the original one.

Thanks as always.

[greyblackfish]

Also that is a very nice plant. Could it be that dens like to stay dormant the first year after adjusting to a new place and then they grow the following year? The other one of mine did the same thing.

[estación seca]

When seedling-sized plants are given proper conditions, they take off growing immediately. Den. phal hybrids are fine with temperatures well into to 90s F / 28-32C. More heat means faster growth, with reasonable humidity.

[Shadeflower]

plants 2 and 4 look healthy - nothing wrong with them even if they are not growing much yet, dens can be slow to adjust to a new environment.

Plants 1 and 3 were fished out of a backbulb bin and sold as something when it should have remained in the bin.

I am guessing plants 1 and 3 came from this other seller? I wouldn't go so far as ES to say that they are both dead - dendrobiums can sprout keiki's but if the canes are weak and shrivelled then ES might be right and they are essentially dead already, I'd tend to agree that 1 & 3 really look on the worse end of things.

[Ray]

Originally Posted by greyblackfish

I fertilize every other week. I will try every week instead.

Before you do that, what is the formula and exactly how much fertilizer are you giving them? (Please give teaspoons/gallon or some other real measure, and not the nebulous “half strength”.)

Fertilizer is a very low-demand item for orchids, and might not be the issue at all.

[greyblackfish]

Originally Posted by Shadeflower

plants 2 and 4 look healthy - nothing wrong with them even if they are not growing much yet, dens can be slow to adjust to a new environment.

Plants 1 and 3 were fished out of a backbulb bin and sold as something when it should have remained in the bin.

I am guessing plants 1 and 3 came from this other seller? I wouldn't go so far as ES to say that they are both dead - dendrobiums can sprout keiki's but if the canes are weak and shrivelled then ES might be right and they are essentially dead already, I'd tend to agree that 1 & 3 really look on the worse end of things.

Actually my bad, I didn't do a good job of explaining. Plant 3 and 4 are the same plant but pic 4 is the before and 3 is the after. 1 and 3 are from the same seller and most of the orchids I received were janky. I had one cattleya with no roots that died on me pretty quickly.

Plant 3 was mostly my fault for not knowing how to pot it. All the plants I got from Olympic orchids came very well packaged and are doing great. I believe plant 2 is growing new roots but I haven't seen much growth in the youngest cane. For almost 2 months now plant 1 and 3 have looked that way and stayed the same. It wouldn't be hard to believe that they might be dead.

---------- Post added at 01:53 PM ---------- Previous post was at 01:49 PM ----------

Originally Posted by Ray

Before you do that, what is the formula and exactly how much fertilizer are you giving them? (Please give teaspoons/gallon or some other real measure, and not the nebulous “half strength”.)

Fertilizer is a very low-demand item for orchids, and might not be the issue at all.

I use a powder fertilizer of 30-10-10, just the miracle grow brand off Amazon for $5. I usually make 1 gallon according to instructions and when it's time for feeding I dilute it down to half since I would rather feed a little less than more. I use rain water when I can but sometimes I just use tap water that has sat out for a day. Most of my orchids get the half diluted solution once every two weeks.

---------- Post added at 01:56 PM ---------- Previous post was at 01:53 PM ----------

Now with all my dendrobium failures I kind of want the challenge again and see if I can do better with some new ones.

[estación seca]

Before you get more... what are your day/night temperatures, now and in the winter? Humidity?

[greyblackfish]

Originally Posted by estación seca

Before you get more... what are your day/night temperatures, now and in the winter? Humidity?

Well I keep them indoors. Day's high is 85 F and night's low is 72 F. In the winter it's more like high of 75 and low of 65. That's indoors. The humidity in my area is usually 50-80%.

Outdoors, the temperatures are more extreme. 75-100 in summer, 40-75 in winter. Humidity is always pretty high.