Fall is here, dormancy is near

[zacharybright]

Well, Fall Equinox was on the 23rd this month, and although I don't think anybody's plants are going dormant yet in most zones, I'd like to begin a discussion on what we cultivators do to keep our plants healthy over the winter. What techniques are being used to prevent death from freezing, pests, and disease over the cold months, and what mistakes have we all learned from? 

Here's my dormancy story: Last winter, I had a terrible epidemic of rhizome-rot in all of my sarracenias, killing some very dear ones and leaving the rest frail. It seems to me that the contributing factors were keeping the plants too wet when the temperatures weren't freezing and not checking on the plants regularly. I was able to save some of the plants by bare-rooting them, separating all of the growing points, severely excising all of the brown, infected tissue, and then treating them all with fungicide. If anybody else is reading this who lives in a humid climate, I would advise keeping your sarracenias well-drained and checking on them regularly over the winter months, especially if it isn't freezing out. 

[jdallas]

Hi Zach,

Here in the Pacific Northwest I find a common mistake of newer growers is to try and baby the plants too much. There's a tendency to want to move plants to sheltered areas for the whole winter. I've done this myself, and often paid for it. Leave the plants out in the rain in shallow trays for the winter. You want them to be rained on since it has a constant flushing effect, and the plants are exposed to UV light and wind that keeps fungal spores at bay. Be sure that the water trays are shallow, because being too deep can cause problems, especially for Venus Flytraps. Having plants in larger pots or planters helps out immensely too. Only shelter them when we are threatened with an Arctic cold spell. When you cover plants, or bring them to a garage that is when you need to spray with a fungicide. When we are back to our regular cool rain, right back out they go.

Good hygiene is also important. Clip off any dead material since that is where fungus likes to grow. I recommend cutting off all leaves of tightly growing species such as S. rubra varieties to open up the rhizome some, and minimize places where fungal sprores can get a start.

Over the years I've lost 10 times the number of plants that I've tried to keep in some kind of greenhouse or cold-frame for the winter. My very first S. x Adrian Slack I lost because I wanted to "protect" it. It was in a glass cold-frame, I didn't pay enough attention to it, and lost it to Botrytis. I have another one now, it stays outside in our pools, not a problem. We cover the pools when it gets very cold, and last winter we had two spells, one that got down to 7 F, and the other 8 F. We have very few losses. The covering is removed as soon as the weather warms back into the 40's.

Winterizing is different for folks in much colder parts of the country, but in our Maritime climate of the PNW, I've had good results with these techniques for decades. Much of what I originally based this on was information from Adrian Slack's books back in the 80's and 90's. The UK has a very similar climate to ours, so his techniques have always worked well for me.

Jeff

[fredg]

I agree with Jeff, I originally tried to give too much protection, extra bubble insulation on the greenhouses and a heater to keep them frost free. I managed to acquire botrytis and rhizome rot. Nowadays I keep the vents open full, no insulation and no heating. Very rarely do I get a problem. My plants have been down to 0F a few winters back. The Sarracenia that appreciated it the least were minor and psittacina which seemed to take an age to restart growth in spring.

[zacharybright]

Thanks for the tips, Jeff and Fred. I'll make sure to give my temperates some tough love this winter. One thing I remember doing is filling the trays all the way up to the soil when it began to freeze, because I heard that water could be a good insulator. It seems like that isn't necessary, though. I'll check out some of Slack's work, too.

[jdallas]

Hi Zach,

One point I do want to stress for Pacific Northwest growers is that you do need to pay attention when we might be having an Arctic weather system coming through. Plants need to be covered or sheltered when temperatures are going to be in the teens F. Plants in pots will have trouble with dehydration during cold, dry spells that low. They just shouldn't be covered or sheltered all winter here. That's what leads to mold issues. If you get our nursery newsletter, starting this winter, we will send out alerts to PNW residents when we might be having a weather system like that come through. We watch the weather closely since we have to cover a quarter acre of pools when temperatures are going to be very low. You can PM me if you want more information about that.

Jeff

[fredg]

I'm not so sure flooding the pots in winter is a good idea. Wrapping the pots in bubble insulation may be however. or a sand plunge to insulate the pot sides. Then it just needs horticultural fleece on the tops when the arctic weather fronts are forecast.

[jdallas]

When I mention pools in our nursery, each one has holes cut in the sides to maintain roughly a 1" water level. We try to avoid having the pots totally flooded. I have to check pools throughout the winter to make sure leaves and other detritus doesn't cause the pools to flood. The one exception would be S. psittacina that is adapted to such flooding.

Bubble wrap is a great idea for smaller collections. What does the sand plunge consist of? Do you just bury pots in sand?

Jeff

[fredg]

Yes on the sand plunge Jeff. It's just a sunken or raised bed filled with sand and the pots plunged into it. Great for insulation.

A large planting tub or a cheap children's plastic paddling pool*, with the appropriate drainage holes cut, filled with sand would suffice for a small collection.

* Example:- www.discountpoolproducts.co.uk/intex-45-crystal-blue-pool---new-1166-p.asp

[zacharybright]

Thanks for the heads-up, Jeff. I'll subscribe to your newsletter so I can get those critical forecasts.

I really like your sand-plunge idea, Fred. It sounds like a great substitute for water as an insulator. Do you suppose I could use fall leaves instead of sand?

[fredg]

I would prefer the sand but a good mulch with leaves is certainly better than flooding in winter

[isteveb]

Anybody have any thoughts on flytraps in South Florida? I just moved here and am concerned that the plants will not get cooled enough to trigger a good healthy dormancy period. It does get down into the high 40s on occasion but not consistent enough..mostly only down to the 50s and 60s F.