Overwintering Cacti

[Mr. Bowser]

So, I brought the cactus collection inside the house for overwintering. They receive light from a metal halide currently 14/10. I've stopped watering the large trichs, and am still watering the year old trich seedlings (about 10-20 cm tall now).

I'd like to keep the seedlings growing steady through the winter if possible, while keeping the large ones dormant. I'm thinking that 14/10 is too long of a day length for dormancy, some of the large trichs seem to be getting thirsty/hungry. If I drop the daylength to 12/12 or 10/14 can I force dormancy in the large ones, while keeping the seedlings active just by watering/feeding?

Thanks!

[shruman]

Its more the temperature than the hours of light they get that will send your cactus into dormancy. Not exactly sure what temperature is needed to make them go dormant but if your house is comfortable they probly will not go dormant.

If they are warm with little/no light they will etiolate ( grow tall & skinny searching for light & may lack chlorophyll).

I overwinter in the shed ;)

[Auxin]

Yeah, dormancy in trichs is not a factor of day length. And lots of light will not assure no etoliation, as hot lights will cause etoliation (I've grown directly under 400 and 1000 W MH, cacti etoliated under both, I'm told its the infrared from the heat of the bulbs)

I just made most of my collection go dormant. I went 3 weeks without watering them to get the soil dry and moved them to cold windows and a cold pantry I made out of a bedroom. They wont grow until spring, but that also means they wont etoliate.

[Mr. Bowser]

Cool thanks! I wasn't sure what triggered dormancy, and kept getting unsightly etoliation when overwintering in the house using MH

Come to think of it last year, the cactus I was lazy with and kept outside until it got really cold seemed a bit less etoliated in the spring than the ones I brought in earlier while it was still warmer out.

Guess I could put them outside and out of the rain to get them to go dormant, its probably cold enough now to make them go dormant but not cold enough to be harmful.

So once they're dormant, can I bring them indoors without breaking dormancy? Would distant MH light be ok without breaking dormancy? Or should I just let them have very minimal light to maintain dormancy?

Ambient temp in the house in the winter is 15-20 C, it would be ok, but not ideal to have them in a room at around 10 - 15 C

[Evil Genius]

5b, whats that? Europe? Must be sometimes like my climate so i would recommend you to water large cacti as soon as you take em in. Cold an dark. Most houses are a lot warmer than how they should be for cact. 5 degrees is pretty good for Trichos. Not sure how big your 1 year olds are but i wouldnt water my small ones over winter either. Because you should only water them if you have it warm and the moment you turn up the heat you get all kind of other trouble inside. But it all depends, you know. In the thread about the rock dust from the other day i posted a pic of my one year olds. If yours are a lot smaller than these, i think its better to overwinter them warm and under a good Lamp hat has at least 150 Watt. Without light, its a pain in the ass.

Edited October 6, 2012 by Evil Genius

[Mr. Bowser]

5b in USDA... but the last few winters were much warmer than 5b.

The little seedlings in question are actually 2 yr olds (I was mistaken of their age) and are about 10-15 cm, and don't seem to be etoliating under the MH yet.

The larger ones I'll stick outside until they go dormant. Its supposed to be 5-10 C and dry for the next week hopefully they'll go to sleep since they haven't been watered in a while.

Thanks for the advice!