Cold snap

[tenman]

Growing in a greenhouse in Ohio with mixed genera, I can't always give each group of plants perfect conditions at all points of the year. Hence, some go outside during the warmer weather for more sun (schomburgkias, laelia anceps, rupicolous laelias, etc.), the disas go outside during the same period for sun and temperature control (special cold-water flowtray set-up), etc. Now, in addition to the laelia purpurata group, I have put maybe 150 or so paphs out as last year, only this year hope for at least 4-6 weeks of 40-45F nights, to induce blooming. All BS parvis not currently in spike, all bulldogs not currently in spike, same for strap-leaved ones, including the barbigerum group, etc. But not the maudiae types.

I feel these have underperformed in the past and am thinking this is the next thing to try. I'd like to get that 30+ growth micranthum to put out more than one inflorescence this year (hear that, Leo??), have several henryanums I've had at least 20 years which have never bloomed, and others in the same boat as well, for example. It's been as low as 40 a couple nights and may get down to 37 this week. I'm wondering how low I can let them go without substantive damage to the plants. Ideally, as I said, I'd like to leave them out for at least 4-6 weeks of this treatment. Our weather took a downward spike quickly last year so they only had two weeks of this treatment (which di result in the first-ever blooming of the monster micranthum I've had for eleven years, albeit only one flower). I can cover them if necessary for a one-night cold snap but once it's regularly going below 40 or so they'll have to come in.

I'm interested in hearing input on this.

 

[Leo Schordje]

Paph micranthum and armeniacum are probably good to 35 F or 2 C. Brief light frosts, and hour or so at dawn, probably won't hurt them.

Just before or at sunrise, cold air aloft mixes down, you can get a short but rather cold downrush, that may be rather local, so your weather station might say the low was 37 F at the airport, but you might have local spots with 29 F for an hour or so in low open areas. So leaving true tropicals out into the 30's at night is tricky.

I used to put plants in trays, and do the in & out dance with them. I'd bring them in the one or two nights a week in October when the temps would be below 40 F, and leave them out the other nights when it would be above 40 F at night. Once they were in more than 4 or 5 days, I would give up and put them back into the collection.

Now that my back is giving me trouble, I no longer do this, I have 'the helper' bring the plants in once. It usually costs me either dinner or drinks later.

Himalayan & Chinese species are probably good to the low 40's and upper 30's. I would be cautious about the complex Paphs, I think they will resent temps below 40. Phrags, which are supposed to be cool growers, do not like temps in the 30's. I have lost a few Phrags that way, even besseae and lindleyanum.

The logic is good, but the weather is hard to predict with enough accuracy.

 

[Ernie]

In Aurora, we would grow some plants (couple hundred) outside in, essentially, a cold frame. We could close it down to protect the whole bunch without carrying in and out, and for frosty days, we'd put a small propane camping heater in the cold frame- Coleman SportCat. Really handy to have around the house in general, and pretty cheap ~$35. Ours heats gently for about 12-14 hours on one 16.4 oz propane cylinder. We'd put it in before going to bed and it'd heat through almost to lunch time the next day. We have a Buddy Heater too- it heats stronger, but only lasts 4-6 hours on one tank, but you can hook it up to a big cylinder (grill size) with a hose. This usually let us keep cool tolerant stuff out until the first of November. Will use the same basic idea down here, but hopefully won't have to tote much in at all.

 

[goldenrose]

...... have several henryanums I've had at least 20 years which have never bloomed, ......

I'm in shock!!! What are your night time lows in your GH? I've not had any problems blooming henry or it's hybrids, I have a night time low of 50, last year I upped it to 55, for the multis, can't say it's helped them any. Birk's book says low of 44 so maybe that's what yours need? it's certainly worth a try, you have nothing to lose.
I keep trying a handful of plants, playing the in & out game when needed, haven't had much luck, would think with you being further south, you could get a couple more weeks than where Leo & I are.
Good Luck tenman!

 

[tenman]

I'm in shock!!! What are your night time lows in your GH? I've not had any problems blooming henry or it's hybrids, I have a night time low of 50, last year I upped it to 55, for the multis, can't say it's helped them any. Birk's book says low of 44 so maybe that's what yours need? it's certainly worth a try, you have nothing to lose.
I keep trying a handful of plants, playing the in & out game when needed, haven't had much luck, would think with you being further south, you could get a couple more weeks than where Leo & I are.
Good Luck tenman!

The minimum night temp is set at 55, but right now with it closed up at night it's going down only to 60 or so. I have the vandas, bulbos, phals, and catasetums to consider. I tried a low of 50 briefly last winter. All the catts got botrytis and I had cold damage on some phals and bulbos. The vandasd just stopped doing anything for 6 months and mostly didn't bloom this year.

When I grew out/in, before the GH, I did leave the cold-tolerant stuff out til it was around 45 or so, but it didn't seem to be enough. As you say, nothing to lose from plants that don't bloom anyway. The worst that can happen is I get more freed-up shelf space for plants that WILL bloom.

 

[NYEric]

This is the first year I put plants outside to cool down, some dendrobium kingianums and some hybrids. I will try putting some parvis outside too but its still gettting warm in the daytime. I'll leave them outside for a few weeks and see if the cool nights help any.

 

[Justin]

i grow all my plants inside the house, so we just leave some windows open this time of year to give them a little chill down into the 50s. I think this morning the temp in the house was right around 60F. Works great for roths and other multis, but I'm not growing any difficult species like Tennis.

However, I also have seedlings and I'm also still trying to establish one small roth division (roth 'Sam's Best') from last spring. That was a small division from last February that was set back to just two leaves left and almost died. Still waiting on new roots but the plant is now growing again so i think it is going to make it. I am going to start turning on the furnace at night just for that plant.

 

[Eric Muehlbauer]

I bring in my coldest growing plants when temperatures drop into the 30's. My feeling is that its not too many degrees difference between 37 and 32....so I don't take the chance. I have only seen cold damage in a paph once. It was a night that was supposed to go into the low 40's. A hirsutissimum and a masdevallia both suffered cell collapse. My warm growing Miltonia, completely forgotten, was unscathed.

 

[SlipperKing]

I'm not so sure that temperature is the only key to blooming some of these more difficult-to-bloom plants. I feel a combination of temperature drop, light intensity increase and a change in what you feed the plants. In South Texas we get large changes in temperature from night and day, mid 50's to the mid 80's. It's common to have the heater on at night and the exhaust fans on during the day. My GH is under a fair number of trees which loose their leaves and the light increases. I cut my nitrogen fertilizer in half. From 100ppm to 50 and then I add 2 teaspoons per 50 gal of water of Epson Salts to the water. I will probabily increase the Epson some but did get deformed Phrag flowers when I added 1 tablespoon per 50 gal of water for an extended peroid of time.
I don't recommend high concentrations for a long time peroid, like all winter.
I don't think you'll get the results you're looking for going below 50*F

 

[Bolero]

I think that both temperature and light intensity play a part but I can't be precise about how this affects each species.

 

[rob]

I not sure I should say this but here it goes. I always thought low temps helped parvis, species and primaries, set bud and they might. This year we had one of the most hot and dry springs and summers I can remember in New England, and most of my multi-growth Gloria Naugles, Dollgoldi, Harold Koopowitz, fumi delights and others spiked and bloomed. Could just be maturity, but we are talking 10 + growths. Therefore I think high temps can't be discounted as one of the potential conditions as bud initiators esp. for primary parvis. Not scientific but just an observation of a large primarly parvi collection that I have been growing for quite some time.
Rob

 

[Eric Muehlbauer]

The only time I ever got armeniacum to bloom was after a really warm fall...so warm that none of my complex paphs spiked.

 

[tenman]

The only time I ever got armeniacum to bloom was after a really warm fall...so warm that none of my complex paphs spiked.

Oddly enough, when I pulled plants to set out for the cold snap, I found malipoense and armeniacum already in spike.

 

[Ross]

While changing light and temperature can help initiate flowering, I believe some difficult to flower plants may be that way because of genetics, also.

 

[tenman]

While changing light and temperature can help initiate flowering, I believe some difficult to flower plants may be that way because of genetics, also.

Yes, in fact I have several 'rare, nonblooming varieties' of some species with which I would be willing to part for the right offer