Winter rest for mounted orchids

[Nicolasdperez]

I have a mounted dendrobium aggregatum and neo falcata which I know need a winter rest. Since they get good air circulation, can I get away with watering 1-2 times a week or should I completely lay off the water? Thank you for your help.

[Roberta]

The Neo doesn't need a strong rest... the drying out that happens naturally with a mounted plant should be plenty. I haven't had consistent results with Den. aggegatum (now lindleyi), dryer or wetter, potted plants bloom some years and not others. Mounted should be better... My point of reference is a lot of visits to Andy's Orchids. Andy groups plants by temperature and light needs, and greenhouses/shadehouses get watered throughout the year. There is no effort to separate the "winter rest" ones from the "no winter rest" ones, it would be physically impossible to manage that with tens of thousands of the "winter rest" ones mixed in with the hundreds of thousands of total plants. And they bloom anyway... most are mounted. So the drying that the mounted plants get just in the matter of normal drying seems to be sufficient. I do the same (of course with a lot fewer plants) and get similar results.

What DOES happen at Andy's, and also in my back yard, is winter temperature variation... most of these can grow on the cool side, so are in unheated ambient or barely-protected shade houses at Andy's (and outside at my house) So I strongly suspect that lower temperatures, especially at night, may also be a "bloom trigger" that may compensate for lack of drying-out. (In nature the plants experience much more humidity and dew even if it doesn't rain, so "dry" in habitat is a lot wetter than "dry" in southern California)

[Shadeflower]

I agree.
I will add that reducing water should not be seen as a beneficial thing to do or anything that will "trigger" anything to happen.
So many people think their orchid won't flower if you don't give it a rest. This is not the case.
A rest should be seen as a time for an orchid to build up energy. But in this time orchids can be susceptible to rotting more, cold + wet is not a good clong term combination. But it is hard to keep a mounted orchid too wet that receives the right care.
By this I mean giving it the right kind of rest. When I read someone recommending to give their orchids a rest I picture locking them in a cold cupboard and forgetting about them for 3 months. That would be a death sentence for them. Winter is still an important time for orchids. They never stop growing. That is if they get the right care. So in winter this means giving enough day temps that they can grow and low enough night temps that they don't lose too much energy through transpiration. If you keep them cold all winter they won't grow and if you keep them too warm at night they will lose all the energy they have stored up during the day.

So resting in a lot of cases actually involves providing more light. In nature the leaves fall, they get full sunlight even if it is weaker winter light, this warms them lots. They grow, they store energy, then when the sun goes down they chill right down, neo's can handle down to 5c apparently. This doesn't mean they need 5c to flower or to do well. The aim is just to make sure they keep growing and don't lose too much energy in between. It's more about achieving a 6 degree C difference day and night and having the right humidity.
One important thing to note is that pretty much all orchids stop growing under 18 degrees C, even neofinetia's. So day temps shouldn't be lower than that. Note that in nature the sun warms orchids and even if they might be exposed to a cold winter day they will always be a lot warmer in nature during the day.
Warming an orchid, whether it is the morning sun or a heater will dry it.

So rot should not be an issue but the orchid dehydrating is an issue. Ideally you don't want to water just before dark because that is when it will get cold and things won't dry.

So it's a matter of just not letting the orchid dry too much, you can see how hydrated it is by the plumpness of the bulbs.

In pots in winter orchids will drink less than in summer. You have to weigh the pot or get a good feel for when it is wet or dry and water accordingly. It is very easy to carry on watering and not notice that an orchid might have practically stopped drinking and this leads to a soggy pot that doesn't dry which will kill an orchid easily hence the advice. But like any well meant advice if it is taken too literally then you might end up doing just as much harm by keeping the orchid too dry.

[Nicolasdperez]

Originally Posted by Roberta

The Neo doesn't need a strong rest... the drying out that happens naturally with a mounted plant should be plenty. I haven't had consistent results with Den. aggegatum (now lindleyi), dryer or wetter, potted plants bloom some years and not others. Mounted should be better... My point of reference is a lot of visits to Andy's Orchids. Andy groups plants by temperature and light needs, and greenhouses/shadehouses get watered throughout the year. There is no effort to separate the "winter rest" ones from the "no winter rest" ones, it would be physically impossible to manage that with tens of thousands of the "winter rest" ones mixed in with the hundreds of thousands of total plants. And they bloom anyway... most are mounted. So the drying that the mounted plants get just in the matter of normal drying seems to be sufficient. I do the same (of course with a lot fewer plants) and get similar results.

What DOES happen at Andy's, and also in my back yard, is winter temperature variation... most of these can grow on the cool side, so are in unheated ambient or barely-protected shade houses at Andy's (and outside at my house) So I strongly suspect that lower temperatures, especially at night, may also be a "bloom trigger" that may compensate for lack of drying-out. (In nature the plants experience much more humidity and dew even if it doesn't rain, so "dry" in habitat is a lot wetter than "dry" in southern California)

Thank you once again for your help both of my mounts are from Andy’s so I will be following your advice. I look forward to seeing how the aggregatum does mounted.

---------- Post added at 07:13 PM ---------- Previous post was at 07:10 PM ----------

Originally Posted by Shadeflower

I agree.
I will add that reducing water should not be seen as a beneficial thing to do or anything that will "trigger" anything to happen.
So many people think their orchid won't flower if you don't give it a rest. This is not the case.
A rest should be seen as a time for an orchid to build up energy. But in this time orchids can be susceptible to rotting more, cold + wet is not a good clong term combination. But it is hard to keep a mounted orchid too wet that receives the right care.
By this I mean giving it the right kind of rest. When I read someone recommending to give their orchids a rest I picture locking them in a cold cupboard and forgetting about them for 3 months. That would be a death sentence for them. Winter is still an important time for orchids. They never stop growing. That is if they get the right care. So in winter this means giving enough day temps that they can grow and low enough night temps that they don't lose too much energy through transpiration. If you keep them cold all winter they won't grow and if you keep them too warm at night they will lose all the energy they have stored up during the day.

So resting in a lot of cases actually involves providing more light. In nature the leaves fall, they get full sunlight even if it is weaker winter light, this warms them lots. They grow, they store energy, then when the sun goes down they chill right down, neo's can handle down to 5c apparently. This doesn't mean they need 5c to flower or to do well. The aim is just to make sure they keep growing and don't lose too much energy in between. It's more about achieving a 6 degree C difference day and night and having the right humidity.
One important thing to note is that pretty much all orchids stop growing under 18 degrees C, even neofinetia's. So day temps shouldn't be lower than that. Note that in nature the sun warms orchids and even if they might be exposed to a cold winter day they will always be a lot warmer in nature during the day.
Warming an orchid, whether it is the morning sun or a heater will dry it.

So rot should not be an issue but the orchid dehydrating is an issue. Ideally you don't want to water just before dark because that is when it will get cold and things won't dry.

So it's a matter of just not letting the orchid dry too much, you can see how hydrated it is by the plumpness of the bulbs.

In pots in winter orchids will drink less than in summer. You have to weigh the pot or get a good feel for when it is wet or dry and water accordingly. It is very easy to carry on watering and not notice that an orchid might have practically stopped drinking and this leads to a soggy pot that doesn't dry which will kill an orchid easily hence the advice. But like any well meant advice if it is taken too literally then you might end up doing just as much harm by keeping the orchid too dry.

Thank you for your help. I was wondering why my neo was pushing out new growth if it was going to go into rest, thankfully you have answered that. I don’t think I need to worry about too low temp given I grow them in my room, but should I put them close to a window so they get some variation in temperature at night?

[Shadeflower]

My neo's are still growing a new leaf at the moment but I'm still a newbie when it comes to neo's. Maybe someone who has gotten them through a few more winters than me can advise. If humidity is not too low by the window then that might be beneficial at night but you'd have to remember to move it every morning. I've heard people growing and flowering theirs regularly in comsamt 20 degrees C... I consider them highly adaptable compared to really needing strict conditions but that is just what I've heard

[Roberta]

With regard to the temperature tolerance of the Neofinetia falcata, remember where they come from... Japan gets chilly (even cold) in winter. These were cultivated by the samurai in their homes. Houses didn't have central heat. So these are quite cold-tolerant. Peter T. Lin (Diamond Orchids) grows them (quite a few AOS awards) in inland southern California in an unheated shadehouse in an area that typically experiences frost several times during the winter. That area also gets summers over 100 deg F/38 deg C so Neos are heat-tolerant too. When cold, they need to be kept much drier, and they are fine. Neos may be little, but they are tough!

Neofinetia falcata is used to make cold-tolerant Vanda hybrids (like Neostylis, Ascofinetia, etc.)

[Fairorchids]

I have never given Neos a winter rest, other than the reduced watering frequency I apply to the entire greenhouse.
In the past I went from twice a week to once a week.
In current greenhouse, I water 3 times a week in summer, and about every 5 days in winter.

For winter rest Dendrobiums, irrespective of what Shadeflower suggests, and what Andy does (in his business, it is not important to induce flowering), I strongly advocate a true winter rest for mature plants. What I do:

Sept 15th, no more fertilizer until buds near opening. Thus, the restart of fertilizer varies somewhat. This rule is critical! If you fertilize during the rest season, you get keikis and no buds.

Watering after Oct 15th:
Australian dendrobium (kingianum, speciosum and their hybrids): Reduced to once a month.

Den nobile and it's hybrids: Reduced to once every 2-3 weeks.

Den. jenkinsii & aggregatum: I stop entirely till I see buds. If canes start to shrivel, I might relent and give them a little, but in my high humidity greenhouse, that is rarely necessary.

Once inflorescences have clearly formed, I start watering again, but I do not resume a full watering schedule till the buds near opening.

Younger plants I keep in areas that get both water and fertilizer year round, as they need to grow up.

In a home environment with lower humidity, you would need to apply a little more water during the rest period, but keep it to a minimum (water only if canes start to shrivel).

[Nicolasdperez]

Thank you so much for your info, but I have some questions:

1) drought, not temperature change, is responsible for flowering in den aggreg?

2) I recently got some den nobiles in bloom, so in order to rebloom them next year I should lay off watering around October?

3) I gave my den aggreg fertilizer twice and watered normally since sept 15th…. Does that rlly mean no blooms for me this year?

[Roberta]

Originally Posted by Nicolasdperez

Thank you so much for your info, but I have some questions:

1) drought, not temperature change, is responsible for flowering in den aggreg?

2) I recently got some den nobiles in bloom, so in order to rebloom them next year I should lay off watering around October?

3) I gave my den aggreg fertilizer twice and watered normally since sept 15th…. Does that rlly mean no blooms for me this year?

1. if you ask 5 people, you may get 8 opinions. It's nickname is Den. "aggravatum". Since everybody's conditions are different, there' are likely to be several "right" answers.

2. If your Den. nobile hybrid is in bloom now, it has been hybridized with other species and hybrids that likely have less need for winter rest than the species Den. nobile. That being said, the advice of "no water from Halloween to Valentine's Day" is a good way to kill the plant... I learned that the hard way, it may work in Hawaii or south Florida with high humidity, at my house it is far too severe. I'll reduce the frequency of watering but not eliminate it.

3. You'll find out next spring.

[Ray]

Not “drought”, per se, but a critical side effect of less water - less food.

In nature, many orchids rely on rainfall to deliver much of their nutrition (microbes can also deliver some). Less rain = less nutrition, especially nitrogen.

In my experience, water reduction is unnecessary, but food reduction - even elimination for some plants - is critical.