Wintering, how dry is too dry?

[graffiti]

Good morning all.

After two months of almost no rain here in CT, I'm looking at a two day rain storm tomorrow and Friday. Which makes me think it's about time to bring my small but growing collection back inside.

Now, I should state that I've had a few cacti for years (P. turecekiania and the R. muscula are about 10ish years old), but I've never really taken correct care of them through the winter, apparently. So I'm reading here and realizing that I need to find a place that gets cool/cold and keep them real dry. But that worries me. I grew up around bedding-plant greenhouses and the idea of completely dry soil makes me think desiccation which is the easiest way to kill C3/C4 plants dead. I nearly killed my Aloe humilis 'Hedgehog' by, I assume, keeping it too warm and not watering it enough two winters ago, or maybe just not watering enough.

All of that said, however, I do feel I have the right place to winter my cacti. My bedroom faces south and is unheated in the winter. On cold nights, (guessing here, I don't have a thermometer in my bedroom) temps will get down near freezing, and probably a little below. Maybe a lot below when we get a windy night down around -20°f.

I'm going to toss up a list of the species I have for advice on which ones can and can't take winter treatment of below freezing.

So without further ado here's the list. I'm going to put pot size and material with each one, as I'm sure that effects how much water they will need.

Astrophytum capricorne v minor SB323 (3-1/2" plastic)

Chamaelobivia 'Rose Quartz' (6" terracotta)

Coryphantha pusilliflora (3-1/2" plastic)

Echinocactus grusonii (3-1/2" plastic)

Echinocereus carmenensis SB1476 (3-1/2" plastic)

Echinofossulocactus crispatus N83.001 (3-1/2" plastic)
Echinofossulocactus erectocentrus SB1150 (3-1/2" plastic)
Echinofossulocactus lamellosus CH260 (3-1/2" plastic)

Espostoa lanata (2-1/2" terracotta)

Ferrocactus latispinis (2-1/2" terracotta)

Gymnocalycium baldianum (3-1/2" plastic)
Gymnocalycium quehlianum v albispinum R103A (3-1/2" plastic)

Lobivia haematantha v elongata MN19 (3-1/2" plastic)

Mammillaria bombycina (4" terracotta)
Mammillaria huitzilopochtli FO-13 (3-1/2" plastic)
Mammillaria elongata crista (6" terracotta)
Mammillaria matudae (4" terracotta)
Mammillaria spinosiss (4" terracotta)
Mammillaria nejapensis (4" terracotta)
Mammillaria gracilis fragilis (2" plastic)

Matucana haynei KK275 (3-1/2" plastic)

Neoporteria taltalensis (3-1/2" plastic)

Opuntia ficus indica (3-1/2" plastic)
Opuntia subulata crista (6" terracotta)

Parodia turecekiana (8" terracotta)

Rebutia muscula (8" shallow terracotta)

My biggest concern is for the ones in small terracotta pots. Seems that my house in the winter would be too dry even for cacti. I'd rather not kill any of them. My real concerns are as follows. The R. muscula was just repotted this past weekend. I didn't realize it but the roots were taking a severe beating due to being in a pot that was too deep and never drying out. The P. turecekiana was the same way this spring, but I've done my best to keep it from getting over watered. Should I let the R. muscula go with no water until spring? Or should I give it a week, water it, then let it dry out?

Otherwise the E. lanata and the F. latispinus have been going through a lot of water. I'm worried about them (and really any in terracotta pots) getting too dry and dying over the winter. I'm not super worried about the ones in the 3-1/2" plastic. Those, for the most part, came from Mesa this spring and look wonderful (except for the [L. haematantha v elongata[/i] which I over-watered and it split, but it's healed and is growing nicely now).

As I said, my current plan is to bring all my Cactaceae in tonight and let them start drying for winter while it's still warm and I have 13ish hours of sun. It's just that this is the first time I'm going to consciously try to put my cacti into dormancy, and that worries me. Should I be watering shallowly during the winter once a month or something? Misting daily? It seems counter intuitive that any plant (even cacti) can go six or more months with no water.

Thanks for all the help and info you fine people have offered, and thanks in advance for the help you will offer in the future!

[iann]

Doesn't really matter whether they're in terracotta or plastic when the soil is dry. The difference is how fast they get dry.

All the species you list are good down to freezing or a little below, some of them a lot below. Plants that have never seen freezing weather before might suffer though, and generally they'll be better frozen just for short periods. Leaving any of them entirely dry for several months in cool conditions shouldn't be a problem. If the conditions are warm they could suffer, though. Most of my cacti go through at least four months without water every winter, and other than shrinking quite a bit they do well. Seedlings might get pampered under lights when they obviously get watered.

The transition into and out of winter dryness is always difficult - it helps to be psychic so you know what the weather is going to be like for the next few weeks.

[DaveW]

As Ian says depends on how cold hardy the plant is and temperature they are kept at over winter. In cool conditions they can go dryer longer since they dehydrate slower. Some cacti with contractile roots also pull themselves down into the soil in winter.

Eriosyce (Thelocephala) malleolata in habitat.

malleolata.jpg (126.34 KiB) Viewed 1527 times

malleolata4.jpg (126.25 KiB) Viewed 1527 times

If your plants have been grown soft and lush though they may not like such cold conditions.

[graffiti]

Hmmm. Well, I'm thinking some heat will be in order. Don't know if a seed mat on a thermostat would be the way to go or just a small electric heater to keep everything above freezing.

[7george]

All of the listed cacti can go whole winter or even 6 months with no water. I would not be worried about seedlings at least 1 cm in diameter. A cactus need much more time to die from draught, at least a year depending on the size and species. Just keep you plants in cool conditions, ~ 15 degr. C or cooler, more or less shaded. The thing that can kill them in winter is some remnant moisture in the soil. If you suspect some wet pots left after the last storm, better take the plants out of it and keep it bare-rooted until March. Provide regular air circulation. That is my experience from many years. Spraying on is possible but not necessary if plants are dormant.

[graffiti]

I was thinking about dormancy yesterday, and instead of starting a new thread, I figured I'd bump this one.

My question is this: Is sunlight bad for dormant cacti? It seems as though the would get plenty of sun even in cold months in habitat, but I always see people talking about putting them in a dark place. I'm wondering how much the dark part of the equation matters. My plan is to winter mine in a mini greenhouse in a south-facing window. Now I'm wondering if that's a bad idea or if I'm just over thinking.

[Steve Johnson]

I was thinking about dormancy yesterday, and instead of starting a new thread, I figured I'd bump this one.

My question is this: Is sunlight bad for dormant cacti? It seems as though the would get plenty of sun even in cold months in habitat, but I always see people talking about putting them in a dark place. I'm wondering how much the dark part of the equation matters. My plan is to winter mine in a mini greenhouse in a south-facing window. Now I'm wondering if that's a bad idea or if I'm just over thinking.

As long as cacti are dry and dormant in winter, light (or lack thereof) doesn't matter. The reason for putting them in a cool, dark place would be if warmth indoors might encourage them to grow, which in turn leads to etoliation when they don't get enough light. Your mini greenhouse should be fine. In fact, if you plan on growing Discocactus and/or Melocactus, heating it to keep the overnights at about 40 would be perfect.

[greenknight]

I keep most of mine where they get little light, and they get a bit faded looking by Spring. They have to be gradually accustomed to the sun when they come out of dormancy or they can sunburn. Some sun is better, actually, but it's not real important.

[graffiti]

Thanks gentlemen.