Water for winter conditions in L.A.?

[Steve Johnson]

Back in June I purchased a small collection from the California Cactus Center (Pasadena, CA). Their cactus mix seems to be working well. I'm adding an additional 20-25% pumice for 3 Astrophytums, a Cephalocereus senilis, and a Melocactus matanzus. I'm a few miles south of downtown Los Angeles, so I wanted to find out what the general rule would be in terms of winter. The winters in my part of L.A. generally don't go down much beyond the mid-40s (F) at night, although believe or not we can get very occasional frosts.

I keep all of my cacti under a shade cloth enclosure, with a clear plastic sheet on top during the wintertime to avoid drenching rains. Under those conditions, would monthly watering in winter be acceptable for most cacti? On the flip side, are there certain types that should stay dry before they come back into spring? For example, I find Melocactus rather tricky, and I won't let mine stay outside if it gets below about 45. I don't know if it should get any water at all in winter.

Thanks for giving me some advice on all this.

Steve

[vlani]

If it stays above freezing I'd just keep them outside, no shade for the winter.
Most plants tolerate occasional frost, but there are exceptions.
Melocactus would like it warmer, so windowsill for it.
I'm in Bay Area and we do get real frost here at nights. I have to use heat in my GH.

[CoronaCactus]

That about covers it. I'm not that far away in Corona (Riverside) but i'm probably much more dry and probably 10*+ warmer. Frost happens rarely. For most species, i leave them go very dry, as in zero water until mid February-ish. I cover a shadehouse with polycarb and wrap the top half in plastic leaving the bottom open for airflow. Some get a drink here and there, otherwise they all stay on the wagon I do have a M. azureus in the ground, 4 years and it's still there. Fighting off a raging Echeveria

At the nursery, i keep Melocactus in a GH that can dip into the low 40's by night, but can also jump to the low 100's by day.

[Tony]

Im in the Chino valley where all the coldest air seems to end up, so I do see quite a bit O frost. Without a heater, Adeniums are out!
I have already been scraping ice off my truck, three days in a row now.
That said, I grew a Melocactus matanzanus and M. peruvianus(I think)in the ground here for 5 years with just a clear overturned bowl for protection on the coldest nights, 34f or less.
They looked so good infact, that I potted them both up for a show and the M. matanzanus died soon after.

I grow all my special plants(with the exception of most Dudleyas) on covered benches that get wrapped in plastic. These are the ones I am trying to keep looking perfect, doesn't always work out but definitely helps.
During long dry warm spells, I do give my melos (now all in pots) discos and some notocactus and mamms, particularly species that have already been proven in the ground, a little drink during the winter months.

I keep all my astros dry from now until spring, but know some folks that grow some in the ground with no problems as long as they have great drainage. Im going to start experimenting with them next year.
I did have three large Cephalocereus senilis in the ground but lost them all and dont know why(Gopher+ excess moisture?). I would just keep them mostly dry, with just a little water if its going to be warm for a few weeks?

[RichR]

We are all concerned about our outdoor cacti getting wet and cold in the winter for fear of rot. Where exactly does the danger lie? If it rains on my cactus bed in December, how cold does it have to get the next day to fall into that dangerous "wet and cold" category: 50F? 40F 30F?

A cactus nurseryman in San Antonio told me he has never lost a plant in the ground to wet and cold conditions. San Antonio gets lots of both every winter. He's been in business for 20 years.

[iann]

We are all concerned about our outdoor cacti getting wet and cold in the winter for fear of rot. Where exactly does the danger lie? If it rains on my cactus bed in December, how cold does it have to get the next day to fall into that dangerous "wet and cold" category: 50F? 40F 30F?

A cactus nurseryman in San Antonio told me he has never lost a plant in the ground to wet and cold conditions. San Antonio gets lots of both every winter. He's been in business for 20 years.

Fickle thing, memory. Probably he hasn't lost anything for many many years because anything that wouldn't survive in the ground died decades and so and he doesn't grow them any more

The ground is also very different from a pot. Open ground drains very quickly and the top inch or two in particular can be dry in hours. In a pot only a certain excess of water drains past the bottom of the pot and the rest is stuck right where a cactus doesn't want to be wet and where it can freeze easily.

[RichR]

What about the first part of my question:

We are all concerned about our outdoor cacti getting wet and cold in the winter for fear of rot. Where exactly does the danger lie? If it rains on my cactus bed in December, how cold does it have to get the next day to fall into that dangerous "wet and cold" category: 50F? 40F 30F?

(I need to remember not to ask more than one question at a time--folks tend to focus on the last thing I said and forget the first.)

[iann]

Depends on the cactus. Pediocactus love to be watered when it is below freezing at night. Echinocereus don't much care for it, but they won't die. Try that with a Pilosocereus and I don't think it would live long. So ... how long is a piece of string?

[RichR]

Thanks, Ian. Nothing like trial and error to find out, I guess. My in-ground cacti are mostly the Chihuahuan Desert cold-hardy type: echinocereus coccineus & pectinatus, various escobarias, some coryphantha echinus and echinocactus texensis and horizonthalonius.

Of course we are in a long-term drought that is forecast to continue through at least winter, so it's probably not going to be an issue this winter anyway.

[cactushobbyman]

iann, I agree about the mind. 90% of my cacti garden is outside and over the years if they make it, they make it, and if they don't, I stay with the ones that make it. My ground is heavy clay and stays wet throughout the winter and we have may frost days. This years I have put some cacti in the garden that I know will not do good in the frost and I made mini greenhouses out of the left over scraps of the poly. from my greenhouse. Come spring I'll know if that works.

[Steve Johnson]

Thanks for weighing in, everyone. I must confess that I was late in the game on my plastic sheeting, but I finally put it up last weekend -- just in time for the downpour we got on the 20th. The plastic over my shade cloth stays up until early April. I add a piece of sheeting over the front of my enclosure, but only for days when there is a chance of rain. When there's no rain, the front comes off and my plants get plenty of ventilation. While all this won't be totally 100% waterproof, it's as close as I can make it, and I hope good enough that if there's any small amount of rain sneaking in it won't bother my "babies". Now, if you don't mind, I want to ask a question:

The plastic sheeting I use is clear (or something close), and I find that the enclosure looks like a little greenhouse. Problem is that I just don't have the time to keep taking it off and putting it back on over the shade cloth while I manage the winter situation. When it's wintertime and the weather is sunny, do you think my plants will still get enough light? Here's a photo so you can get a look (hopefully it'll give you a decent idea):

Just for reference, I took this in L.A. earlier today, about 12 noon. Front of my enclosure faces south, and you'll see the sun go unobstructed from east to west every day.

I'm onboard with what CoronaCactus said -- cacti in the winter need to stay dry. However, I just want to make double-sure about the specific cacti I have in case there's some info I should know:

Astrophytum asterias, capricorne v. senilis, and myriostigma
Cephalocereus senilis
Copiapoa hypogaea (has a bunch of pups, and a new one just came in)
Echinocereus pectinatus v. rubrispinus
Espostoa lanata
Gymnocalycium ochoterenae
Mammilaria microcarpus and spinossissima
Melocactus matanzus
Neoporteria nidus v. senilis
Opuntia articulata
Sulcorebutia rauschii
Turbinicarpus macrochele v. polaskii, schmiedickeanus, and swobodae (Think schmiedickeanus and swobodae may have been misidentifications by the California Cactus Center. These are still Turbs, though.)

Guess my primary concern is that some of my cacti may need a touch more than "set it and forget it" for the whole winter. I know we can get days of unseasonbly hot weather over wintertime here, so any thoughts on your part will be greatly appreciated. Oh, one more thing (call me Columbo!). I was reading up on Melocactus at Cactuspedia. I saw this passage which I found rather confusing: "Melocactus rests from October to April but can’t stand cold, or even fairly cool temperatures, so is indispensable to keep it above 8-12°C at all times, severe damage or death occurring at temperatures that the great majority of cacti wouldn’t mind in the least and prefer more frequent water in winter than other cacti, say once a month." Okay the first part about cold conditions was fine. Then I couldn't figure out what the guy was trying to say. Maybe it's because I sometimes get "senior moments", although personally I think the wording was just clumsy. Anyway, is it correct that Melocactus should get some watering once a month during the winter? If so, and my M. matanzus is in a pot, should this be a light amount of water, or draining through to the bottom of the pot?

Thanks again!

Steve

[iann]

Yes, that's it. Melocactus prefer to get some water in winter but absolutely only if they are good and warm. They aren't really unique in that but they are probably the most popular globular cactus in that category.

[Steve Johnson]

Yes, that's it. Melocactus prefer to get some water in winter but absolutely only if they are good and warm. They aren't really unique in that but they are probably the most popular globular cactus in that category.

Thanks, Ian. Your advice is spot on, and I'm keeping an eye on winter temps here in L.A. every day. Yes, I'm that nuts as I even look at the 10-day forecasts on weather.com. For example, we've had a few days of about 80 degrees, and it'll be going right back down to the 60s. Given our overnight temps (mid 40s to low 50s), I think my Melocactus isn't due for some watering anytime soon. However, I'll definitely keep monitoring the weather situation.

By the way, I saw some photos of your lovely Lophophoras. Unfortunately Lophs are strictly verboten by law under California. Too bad, because I would've enjoying having one in my own collection.

Steve