Which orchids in YOUR collection get a winter rest?

[RoseSD]

I would like to understand the reason thay Dendrobium needs to rest in winter. Is it because it grows mostly outdoor and winter is cold in most places? Where I live in southern CA the winter evening never goes lower than 50. Do mine still need this rest?

[Roberta]

It depends which Dendrobium. Some come from monsoonal climates where they get heavy rain in the summer, but very little rain in winter (when it is also cooler, and brighter with no clouds) Particularly at higher elevations and higher latitudes. Others come from more tropical climates where they don't get that drying out. I somewhat dry the nobile-types and dry Den aggregatum more, but in southern California you have to temper the advice a big... in habitat they still get dew. They don't get days of 90 deg F with 10% humidity. Most important is to stop fertilizer. I have found that then the drying-out is less important, for those outside... the cold is also a trigger for spring blooming. (Your nights get only down to 50 F? A lot cooler at my house... occasionally close to freezing. ) The cold nights don't harm those Dens. If you have the so-called Den-phals, they are tropical and need more like Phalaenopsis temps (but more light) and don't want to dry out.

Remember, the hybrids have characteristics that go back to their ancestral species. The ones that want a winter rest (no fertilizer, reduced water, chilly nights in some combination) have ancestors that come from places like the Himalaya foothills, southwest China, northern parts of southeast Asia, Japan, Taiwan etc. and coastal southern Australia. The ones that don't have ancestors from sea level and low elevations near the equator.

[RoseSD]

I have a Dendrobium antennatum and a Dendrobium linawianum. Both are seedlings. Should they be watered less? How much less?

[Roberta]

D. antennatum is a tropical species. Warm, no rest. D. linawianum is from China and Taiwan, around 1000 m. That one can take cold, and reduced water. However, being a seedling perhaps both in moderation. How is the D. linawianum potted? Or is it mounted? Andy doesn't dry anything out... all are in the same area based on temperature. But mounted plants dry fast. I'd cut out any fertilizer. If it has been indoors so that it hasn't been acclimating, maybe put it near a window where it can be cooler but likely best to not put it out now. If it has been outside, it would be fine if on the dry side. Next year, outside for that one.

[RoseSD]

Both are in pots. My D. linawianum is smaller, packed in loose moss. D. antennatum is larger from a different supplier but packed in barks and dries pretty fast. They sit together in a sunny spot by the window but it is a pain to water antennatum more often!

[Roberta]

Well, they have different needs... Once you see new growth, you might want to repot the D. antennatum in smaller bark. But over time, they're going to get different treatment anyway. You will need to continue to grow the Den. antennatum indoors, particularly when night temperatures get below 60 deg F/15 deg C or so... it's a warm grower. Phalaenopsis temperatures but a lot more light. In the spring, you'll want to move the Den. linawianum outside, and long-term, grow it there. It will get the cool winters that it wants. Again, when you see new growth you'll probably want to repot, into bark. Then, if it dries fast that will make winter maintenance even easier since you'll be able to water with the the rest of your outdoor orchids without worrying about overwatering. For this winter, just baby them a bit. Over time, Den linawianum will be the easier one... it'll grow outside all year around where you live, not need a lot of TLC. Getting enough light for Den. antennatum indoors, especially in winter, is likely to be the bigger challenge. (If not enough, it'll grow but be more reluctant to bloom)

[RoseSD]

Here they are getting additional desk light lol. I use wet paper towel instead of moss to top the bark wet. Hope it is not a problem?

[Roberta]

Shouldn't be a problem. Is the big one the antennatum? Looks like a good healthy plant. Actually both look excellent.

[RoseSD]

Originally Posted by Roberta

Shouldn't be a problem. Is the big one the antennatum? Looks like a good healthy plant. Actually both look excellent.

Yes!

[Roberta]

Well, Den. antennatum is the larger plant when mature (they can get rather large). So Den. linawianum is actually a bit larger than a "seedling" ... looks very healthy.