Dendrobium griffithianum Care Tips?

[mgxoxo]

Hi! New orchid grower here. Picked up a Dendrobium griffithianum when a breeder came into town. Any tips for successful growth? Mainly wondering if my potting mixture is suitable (perlite, orchid bark, and SunGro Black Gold All Purpose Natural Potting Soil Fertilizer Mix 0.13-0.04-0.13), about watering frequency and quantity, if the potting space is okay, and if I should place a humidifier near it.

Here are notes I’ve taken for how-to care so far: 


Dendrobium griffithianum Care

Water:
-Water in morning ~1-2x per week. Allow potting medium and roots to be almost dry between waterings.
-Use distilled water or rainwater.
-Leaf drop indicates a need for more water, humidity, and warmer temperatures. Begin decreasing water for winter rest after blooming. Do not allow pseudobulbs to shrivel. Increase water again in spring when new growth appears.

Potting Medium:
-Mix of perlite, orchid bark, and SunGro Black Gold All Purpose Natural Potting Soil Fertilizer Mix (0.13-0.04-0.13)

Placement:
-On slightly shaded south facing windowsill.
-The pot that is used should only be slightly bigger than the plant’s root ball.
=Keep in mind that temperatures close to the window on a windowsill will be colder or hotter than your general house temperature.

Fertilizer:
-When new roots begin to grow, apply a high nitrogen fertilizer (9-3-6) in spring and a high phosphate fertilizer (3-12-6) from late summer to fall. liquid fertilizer three out of four weeks. On the fourth week, flood potting media to rinse fertilizer salts.

Humidity:
-75% humidity is ideal with 65% in winter. Use a humidifier if necessary and a fan set to low to provide air movement. Home growers: remember 50% is the maximum recommendation.

Sources:
-https://gardens.si.edu/collections/plants/orchids/orchid-care-sheets/dendrobium/#:~:text=Since%20Dendrobiums%20are%20often%20large ,in%20the%20spring%20and%20summer.
-https://www.aos.org/orchids/culture-sheets/novice-dendrobium.aspx
-https://www.thespruce.com/grow-cane-and-dendrobium-orchids-1902862

Thanks!

[Roberta]

Welcome!

the potting soil part of your mix is not good - just orchid bark + perlite would be desirable.

Don't bother with the various fertilizers - The nitrogen is fine for growth, but the so-called "bloom boosters" are not useful. In the fall and winter when growth slows down, just skip fertilizer altogether and reduce (but don't eliminate) water. In nature, these encounter little rain in winter, but get heavy dew. With little rain there isn't as much cloud cover as in summer, so the brighter you can keep it the better. Near a window to be cooler in winter also desirable. In fact, you may get some leaf drop in fall/winter and that is fine - indicating that the plant is resting, and so doesn't need as much water, and no ferftilizer becaue it's not growing much.

In general, orchids are light feeders and fertilizer is the LEAST important factor in culture. When in doubt, use less. Start with half the strength prescribed on the label, once a week or every other week is fine.

Where do you live?

[estación seca]

Welcome to the Orchid Board!

You don't need to post questions twice. Just pick whichever Forum you think is best. If it's truly in the wrong place the moderators will move it.

If you're using regular potting soil in your mix, that won't work. Most Dens. are epiphytes, needing lots of air at the roots. Potting soil has small air spaces easily filled with water. This suffocates orchid roots.

Most Dens. have very small diameter roots. They do well in fine to medium bark mixes, depending on your growing conditions

There is a huge number of Den. species from many different climates. Care is not generalizable. You need to read about species before you buy them so you don't buy something you won't be able to grow. A good starting point is the Internet Orchid Species Photo Encyclopedia, IOSPE, at orchidspecies.com. You can read about Den. griffithianum there. Its relatives in the widespread Asian Section Densiflora take somewhat similar care, though different species need different temperatures through the year, and different amounts of winter water. Most are not easy in a home because they require high Spring-Summer humidity. This one doesn't like getting cold in the winter.

The Smithsonian, AOS and The Spruce have a lot of useful information. The care sheets above are so general as to be completely useless. They don't apply to many hundreds of species of Dens. Sadly, most orchid growing books are the same.

I do recommend the AOS book The American Orchid Society Guide to Orchids and their Culture.

You can also use the Search feature here. From the top menu select Search then Advanced. In the top left search term box put griffithianum. At the right from the scroll forum box select the Dendrobium forum.

[mgxoxo]

Hi Roberta,

Thank you very much for the advice! I will go ahead and remove the soil from the mix and repot with just bark + perlite.

I live in the Southeast (humid subtropical). I don’t want to place my orchid outside because the city air quality isn’t great, and pests have destroyed any plant I’ve put on the porch. My orchid is right by a south-facing window that receives a good amount of indirect light. I can place a humidifier near it if you suggest that may help with conditions.

Originally Posted by Roberta

Welcome!

the potting soil part of your mix is not good - just orchid bark + perlite would be desirable.

Don't bother with the various fertilizers - The nitrogen is fine for growth, but the so-called "bloom boosters" are not useful. In the fall and winter when growth slows down, just skip fertilizer altogether and reduce (but don't eliminate) water. In nature, these encounter little rain in winter, but get heavy dew. With little rain there isn't as much cloud cover as in summer, so the brighter you can keep it the better. Near a window to be cooler in winter also desirable. In fact, you may get some leaf drop in fall/winter and that is fine - indicating that the plant is resting, and so doesn't need as much water, and no ferftilizer becaue it's not growing much.

In general, orchids are light feeders and fertilizer is the LEAST important factor in culture. When in doubt, use less. Start with half the strength prescribed on the label, once a week or every other week is fine.

Where do you live?

---------- Post added at 10:39 AM ---------- Previous post was at 10:31 AM ----------

Hi Estación,

Thank you for your guidance and the links! Based on your and Roberta’s comment, I will remove the potting soil from the mix so it’s just perlite and bark. Hopefully adding a humidifier nearby will help out. I’ll keep researching the resources you’ve provided and D. griffithianum on this site.

Originally Posted by estación seca

Welcome to the Orchid Board!

You don't need to post questions twice. Just pick whichever Forum you think is best. If it's truly in the wrong place the moderators will move it.

If you're using regular potting soil in your mix, that won't work. Most Dens. are epiphytes, needing lots of air at the roots. Potting soil has small air spaces easily filled with water. This suffocates orchid roots.

Most Dens. have very small diameter roots. They do well in fine to medium bark mixes, depending on your growing conditions

There is a huge number of Den. species from many different climates. Care is not generalizable. You need to read about species before you buy them so you don't buy something you won't be able to grow. A good starting point is the Internet Orchid Species Photo Encyclopedia, IOSPE, at orchidspecies.com. You can read about Den. griffithianum there. Its relatives in the widespread Asian Section Densiflora take somewhat similar care, though different species need different temperatures through the year, and different amounts of winter water. Most are not easy in a home because they require high Spring-Summer humidity. This one doesn't like getting cold in the winter.

The Smithsonian, AOS and The Spruce have a lot of useful information. The care sheets above are so general as to be completely useless. They don't apply to many hundreds of species of Dens. Sadly, most orchid growing books are the same.

I do recommend the AOS book The American Orchid Society Guide to Orchids and their Culture.

You can also use the Search feature here. From the top menu select Search then Advanced. In the top left search term box put griffithianum. At the right from the scroll forum box select the Dendrobium forum.

[Roberta]

If you are in the southeast US, I would doubt that you need a humidifier. Don't worry about "bad air" for growing outside. I have a yard full of orchids in southern California... Pests are another issue... and rodents. But if you can avoid those, outdoors is really better as long as temperatures are in range. This species comes from a region where there is a large temperature range - the Baker culture sheet gives a range from 104 deg F to 38 deg F. So unless frost is a danger (when it will need to be brought in) I suggest growing it outside. I have a very small greenhouse, have found that anything that can grow outside does better outside.