Orchid winter rest

[MCSchrum]

I'm sort of confused over this whole dry-cool-winter rest period. I have several different orchids that will require a winter rest period in order to flower next spring. However, I haven't been able to find much information about the duration of this rest period for the individual types of orchids? How long must an orchid rest in order to gain the benefits of this rest? How long is too long? I grow all my orchids on a windowsill. I currently have Dendrobium kingianum, Dendrobium aggregatum, Dendrobium cucumerinum, Dendrobium wassellii, several different Dendrobium Latouria hybrids, Cattleya walkeriana, and several cattleya type hybrids. Can I treat all of these plants about the same during winter, or do the have significantly different requirements for their winter rest periods? I'd appreciate any advice.

[Missanna]

In general orchids that require a dry rest will grow in their season (many make their growths in spring-summer) then they will complete that growth. This is when you start to reduce the water. Instead of watering them as soon as the mix dries out, you will start to wait more days before you water again. This is also when the temperatures drop as well, so the mix will also take longer to dry. Anyway, basically just watch them for signs of dehydration and don't let them get too wrinkly. Some of the dendrobiums really like to dry out, but I can't really give much advice on those. I just grow cattleyas. Anyway, usually they will start growing again in the spring and that is when you start increasing the frequency of watering. Just watch them and listen to them. They will tell you what they need.

[catttan]

Most East and South-east Asian dendrobiums and vandaceous that need a cool, dry winter rest to initiate flowering come from monsoonal areas with a dry 'winter' season lasting between 2 - 4 months (e.g.. your aggregatum or lindleyi. wassellii or wardianum ) the Latourias don't need a winter rest. Most cattleyas including walkeriana don't need a winter rest.

[MCSchrum]

Thanks Cattan, for your response. I live in the Midwestern US. It can get very cold here, -10 F, from late December to early March. I think I will try giving those Dendrobiums a rest for that full three month period. Hopefully that will bring me lots of flowers in the spring.

[78Terp]

Watch them for dehydration. If they start to shrivel, then water them. Don't let them die of thirst. I hear some people mist them once every week or 2. I understand the traditional time frame for the winter rest is Halloween to Valentines Day. That is the schedule I am going to try (this will be my first year of a winter rest for dendrobiums).

[MCSchrum]

Thanks Terp. I may try that too. Those holidays would be pretty good landmarks, so that you don't forget when you began your winter rest. I imagine that your temps in CO during the winter will be similar to my temps here in northern MO, though I bet you get a lot more snow.

[raybark]

The important thing about the rest period is "free from nutrition", not "free from water".

I think a good general recommendation is to keep them hydrated, as Terp suggested, but withhold all food until you see new growth begin in the spring. Folks sometimes wait until there's about 3" root growth on catasinae-types.

[silverstoli]

The important thing about the rest period is "free from nutrition", not "free from water".

I think a good general recommendation is to keep them hydrated, as Terp suggested, but withhold all food until you see new growth begin in the spring. Folks sometimes wait until there's about 3" root growth on catasinae-types.

So, they are removed from the pot and media completely during the rest?

[MCSchrum]

Raybark, that sounds like a very important piece of information. So I guess you shouldn't let your plants turn to orchid jerky, but you should let them dry out and starve them for a few months?

[78Terp]

No, leave them all potted up as they are now. Just stop fertilizing during the Halloween to Valentines Day. Use only water.

After new growth resumes around Valentines Day, then you can begin to add fertilizer to the water again. And increase to your normal watering regime.