Is overwintering in total darkness possible?

[DesertSun]

Hello everybody. I currently have all my cacti in total darkness, as I did not want them to become etiolated. The light is definitely not enough for the cacti in winter, even though we live in a country with plenty of sunlight even in winter. Light levels are never
the same inside and day is short. For now I haven't noticed anything going wrong, but I wanted to ask your opinion. I kept them bone dry since day one I got them a couple of months ago. I cannot give accurate info about the species as they were not labeled, so I took the risk with putting all of them into a dark room, kept the window open at all times so temp. is not high, but neither too low, we have moderate winter temperatures.
Has anyone tried this? Thank you, Marina~~~

[DaveW]

Really it can depend on how high a temperature they are stored at since it is lack of light that causes etiolation if the plants are still growing. If stored a few degrees above freezing you may be OK with them stored in a dark room. I would think your winter light levels are just as great as the UK in winter and if dry and cool winter light would be desirable. The problem will not be the light in winter causing etiolation if dormant, but whether the temperature during the day in your room or greenhouse is sufficient to keep them in growth.

Cacti can be kept in total darkness overwinter if cool. I remember reading about growers in E. Europe before the Berlin Wall came down who could not obtain fuel for heating greenhouses. They used to take their plants out of their pots at the start of winter, wash the soil off the roots, dry them out for a day or so then wrap them in newspaper and store them in their cool cellars over winter. Taking them out and repotting at the start of the next growing season when warm enough.

I have never tried such drastic measures, but my plants in my unheated greenhouse are often covered with newspaper for a week or so in very cold weather with no problems. Obviously the plants would need to be totally dry and dormant and kept cool so there was no chance of growth during the winter for such storage methods, but light would not be the problem since it is only growth without sufficient light that causes etiolation.

[ElieEstephane]

Overwintering in a dark room is doable but not recommended. I used to store a few cacti in the dark but now i leave everything on sheltered balconies. Daiv who is the administrator of this site overwinters all his cacti in a dark cold room (around 7 degrees i think).
However, several problems can arise from this method, namely sunburn in spring. In addition, some plants can still grow if the conditions are suitable even when they are bone dry for several months. I've had that happen to me with two of my pilosocerei. They're on a shaded balcony and last week the temperatures were consistantly 15-22 degrees so they etiolated quite badly. They were my 2 best specimen.
I know that photoperiod does not affect cactus flowering, but light could be better for general health
For mor info, see:
http://cactiguide.com/article/?article=article27.php

[DesertSun]

Thank you both for your answers! Uh oh, someone made a mistake...Let us hope they do not etiolate, at the moment they haven't shown any signs of it. Next year I will leave all my cacti outside, but protected from rain. You are right Elie, sunburn is what I must be most aware, I will acclimate them very slowly. Thank you Dave, I don't have very cool temperatures, this winter has been extremely mild overall.

[DaveW]

If they are going to grow at all due to warmth in what should be the resting season you want maximum possible light during the day to stop etiolation. By that I mean normal winter day length (photoperiod), not artificial lighting increasing the day length or that itself may induce winter growth.

http://www.cactus-art.biz/note-book/Dic ... period.htm

[PresidentKang]

I am currently trying a fully dark, cold overwinter. I had no other feasible option in a small, centrally heated apartment. I'm in the northern US, so we get long, cold, dark winters. I'm basically following Daiv's advice and so far I haven't had any problems.

The last water was in early October, and I let them dry out on an eastern windowsill for another month or so before I put them in the cold dark storage.

I have my plants in a hole in the wall, essentially. It's the metal-lined and vented spot where the air conditioning unit would usually be. Since it's basically open to the elements at the back (it has a vented metal cover but that's it), I lined it with some thin styrofoam from a craft store, and some plastic window sheeting to block drafts and moisture. I covered the front with some cardboard and a heavy curtain, so it blocks the light and the interior heat pretty well. The temp has consistently been between 38 - 45 F (3- 7 C) with low humidity, and it's fully dark all the time.

I just pulled my plants out yesterday to check and everything looked good. All the plants seem to be holding their color well, and apart from some very minor etiolation on one Echinobivia pup (the main plant is still perfect, it's just one pup), none of my plants are etioliated or appear to be stressed. My plants are all your average big box store plants: Echinocactus, Mamillaria, Echinobivia, echinopsis, Parodia, etc. Nothing too fussy or demanding except for one Astrophytum ornatum and even that one seems to be doing just fine. Some of them are a bit shriveled but nothing I didn't anticipate.

My plan is to pull them out when the outside temps start averaging around 35- 40 F, and then keeping them on a shelf about six inches below the windowsill. I'll have some cheesecloth over the top so they'll get indirect filtered light for a few weeks from the window at first, and then gradually introducing a grow light (HOT5 fluorescents with 6500k and 3500k bulbs) and then to the windowsill shelf which gets unobstructed eastern exposure with the grow light supplementing.

I've been taking pics throughout the process and hopefully I will have a photo album update with some blooms this spring! This board has been fantastic for me, as a well-intentioned but occasionally clueless novice, so I'm really hoping I can return the favor with an example of a successful project!

Good luck!!

[DesertSun]

@PresidentKang, I somehow missed your answer, thank you very much! It seems amazing to me, but all the cacti that were kept in total darkness, but one that lost its roots and that I remember was unstable the minute it was bought), seem perfectly fine with it!
No signs of etiolation, no instability that would suggest loss of roots, but of course, they were bone-dry. And comparing it with the Mammilaria that I bought without me noticing that it was watered by the nursery girl, that one I kept in full window light, it took weeks to dry out, and of course, it shows etiolated growth. What that tells me, is that dark and bone dry is very much possible, but inside in room temperature and wet will cause etiolation. Thank you for sharing your way to go method, it is interesting and so informative to see what people do differently in cultivation of their cacti collection.

[PresidentKang]

@PresidentKang, I somehow missed your answer, thank you very much! It seems amazing to me, but all the cacti that were kept in total darkness, but one that lost its roots and that I remember was unstable the minute it was bought), seem perfectly fine with it!
No signs of etiolation, no instability that would suggest loss of roots, but of course, they were bone-dry. And comparing it with the Mammilaria that I bought without me noticing that it was watered by the nursery girl, that one I kept in full window light, it took weeks to dry out, and of course, it shows etiolated growth. What that tells me, is that dark and bone dry is very much possible, but inside in room temperature and wet will cause etiolation. Thank you for sharing your way to go method, it is interesting and so informative to see what people do differently in cultivation of their cacti collection.

Happy to help! But this is my first attempt at anything like this, so I don't want to be too optimistic until they survive the transition and start to show healthy new growth. But so far, everything looks good. The new grow light is on the way, a massive upgrade from the old LED setup I had. I'm really looking forward to seeing how they respond to the light during the growing season.

[DesertSun]

I guess what we have to fear of, or let's say be overly cautious now, is the gradual acclimation of them into the sunlight.
They are very prone to sunburns if I am not mistaken, as they had been in darkness for months. What I will do is when I move them to my balcony, I will first put them into a shaded position, and gradually move them into brighter shade, until they get into sun exposure.

[CACTUSCANADA]

Really it can depend on how high a temperature they are stored at since it is lack of light that causes etiolation if the plants are still growing. If stored a few degrees above freezing you may be OK with them stored in a dark room. I would think your winter light levels are just as great as the UK in winter and if dry and cool winter light would be desirable. The problem will not be the light in winter causing etiolation if dormant, but whether the temperature during the day in your room or greenhouse is sufficient to keep them in growth.

Cacti can be kept in total darkness overwinter if cool. I remember reading about growers in E. Europe before the Berlin Wall came down who could not obtain fuel for heating greenhouses. They used to take their plants out of their pots at the start of winter, wash the soil off the roots, dry them out for a day or so then wrap them in newspaper and store them in their cool cellars over winter. Taking them out and repotting at the start of the next growing season when warm enough.

I have never tried such drastic measures, but my plants in my unheated greenhouse are often covered with newspaper for a week or so in very cold weather with no problems. Obviously the plants would need to be totally dry and dormant and kept cool so there was no chance of growth during the winter for such storage methods, but light would not be the problem since it is only growth without sufficient light that causes etiolation.

Your able to leave your cacti in the an unheated greenhouse all year in the UK Dave? What kinda of interior temps are your experiencing inside the greenhouse?

[DaveW]

The tender ones get brought into the house over winter, but most get down to freezing or just below at times. However they have usually been dry since late September until the end of this month. They are usually covered with newspaper on very frosty nights and days. When they are not growing the papers can be left on for a couple of weeks if needs be without them etiolating. However they would probably do better if the greenhouse was kept just above freezing since the cold makes for a later start in the growing season, plus obviously a shorter growing season, meaning less growth per year.

Should your heating ever break down covering your plants with a couple of layers of newspapers could often save most of your collection.

[NJGardenGuy]

This is a fascinating topic. I have had all of my Cactus indoors since October. Most on tables in front of my living room windows,
but my larger floor plants are in my foyer which is relatively dark (These are all Echinopsis species and hybrids). They have all done
amazingly well. However, I have lost about 20 Cactus that were on the trays in front of the windows. I suspect as a result of No
Water over the winter. They just totally collapsed in their pots. The Temperature of course in the house was warm, because this Winter was extremely cold. My collection has dwindled quite a bit, but the Echinopsis in the dark did very well indeed.

[PresidentKang]

Quick update on my dark winter attempt:

It went pretty well, overall. I took them out at the end of February and spent March reacclimating them to full light. They're under the grow lights full time now, in an east facing window. No sunburn or damage so far!

I had some minor etiolation on some Echinobivia offsets, but other than that they all look the same as when they went in.

They had their first water a week ago, and now the shriveled ones are starting to fill out again and I'm keeping an eye out for new growth or blooms.

So it's definitely possible, I'll consider it a full success when I get some blooms! (Maybe next year, but I'm just glad my collection survived intact!)

[DaveW]

One of the less risky ways to start them into growth again is regular mist spraying, since it does not wet the soil as much at first and dries out by evening, then when you see new spines in the crown start watering.

[J-M]

All my mature cacti are on a north exposed windowsill in a small room in the basement. Most of winter snow was covering the window so they were in almost total darkness. Temperature was between 40-54 F (4-12 C) depending on outside temp. They are still dormant, no sign of growth. Most did shrink, some a lot, but others are as good looking as 6 months ago ! Last watering was mid September.

I plan to take them out in 1-2 weeks and expose them sllloooooowwwwwlllyyyyy to the sun. Wait 2-3 weeks and give them some water !