Artificial Vernalization of Potted Cypripediums

A few days ago I took my Cyp. reginae f. albolabium seedling out of vernalization. This is the only Cyp that I have growing in a container currently, and I'm doing this because it is a fragile young plant - I never plant seedlings out until they are 2-3 years old. Anyway, I wanted to discuss the issue of dormancy in Cypripediums when you are container growing. This applies to seedlings and mature plants alike. Because Cyps are temperate plants, they require a cold winter dormancy in order to survive. During this period the plants die to the ground and rest for 3-4 months. Obviously in the garden nature takes care of this, but if you are container growing, you have to simulate it. The best option with mature plants, if they are hardy in your region, is to sink the pots into the ground for the winter. But if you are growing seedlings, this is undesirable as conditions outside are quite harsh for such tiny plants (although some people simply plant them in protected sites). As well, some people like to have mature Cyps growing at specific times of the year, ie for shows and such. Finally many people grow the more tender species in northern areas and can't overwinter them outside. In these cases, we use a method called artificial vernalization, in which basically the plants are refrigerated for a few months.

Cyps do not need freezing temperatures during their dormancy; in fact this might kill them in pots. Outside, the plants are insulated from the cold by the ground, mulch, and snowcover. In pots they don't get this insulation. So, temperatures of around 3-5 C are adequate for dormancy. Any standard refrigerator works for this. The next thing is soil moisture. Although the plants should have significantly less moisture during dormancy, they should still not be bone dry. As dormancy approaches (signalled by the yellowing of the leaves), gradually reduce watering so that by the time the plant is brown it is just being kept slightly damp. Now, place the pot in a Ziploc bag and seal it, and place it in the crisper drawer of the refrigerator. This will create a humid environment so that the soil doesn't dry out, and the bag should help keep fungi out. However, as there is moisture and there are cool temperatures, you could get mold growth on the soil so watch for this throughout dormancy and pick it out as it appears. I like to prick holes in the Ziploc bag to vent it, which I find helps reduce mold growth. This doesn't work as well for everyone though, I've heard. Also throughout the dormancy, check the soil moisture every once in a while and dampen it a little if it gets dry.

With mature plants, it is usually not feasible to refrigerate them because the pots are too big. For them, you probably have to store the pots in the garage (unheated) or a really cool room in the basement over the winter. In the case of an unheated garage, simply cover the pots really well with blankets, etc. to keep it from freezing.

And that's basically it! All you have to remember besides that stuff is that the plants need 3-4 months dormancy depending on the species (and formosanum appears to only need 2 months). When the time is up, just remove the pot from the fridge and start watering it (put it in a bright location). If the plant starts emerging from the soil while it is in the cold treatment, remove it immediately. I'll be posting pictures of my seedling in the coming weeks.

Spring is Coming...

Although it is bitterly cold outside today, I have hope, because this Paph delenatii, which is generally a spring bloomer, is spiking. This is a first bloom seedling from awarded parents. I am delighted to have it spiking so quickly after I bought it in October at the FOS show. It originates from Paphanatics, the famed Paph breeder. This is a sure sign of spring!

Phrag schlimii 'Allan's Red'

It's always difficult to get a good picture of these because the flowers are petite and are often held at a weird angle. I have found that this species is quite variable in terms of flower quality. This is my second one, which I just bought yesterday. It's not much better than my other one, but as my other one is struggling and this is a robust division, I bought it. This is a difficult species to grow well - I think the key is to use pure water and keep it wet. I have to try to pay more attention to my schlimii plants so they do better - they are temperamental and need lots of TLC.

This species is quite hard to find, but all the serious Phrag growers/collectors have at least one. It is an old species and is obviously very attractive, and is one of the most compact Phrags there is, and a founding species of both pink Phrag hybrids and compact ones. Whilst being compact for a Phrag, this plant is still at least 16" or so in leafspan, and growing in a 1 gallon pot - they get rather large as they clump up and mature. Characteristically, the sequentially flowering stems are short and few-flowered. The flower is less than 2" across but has a light fragrance. While the single open flower on this plant looks ridiculous with so much foliage, when it clumps up more it will have multiple stems flowering at once which looks quite impressive. A specimen plant of Phrag schlimii is always a magnificent sight to behold. Here's to Colombia's most beautiful orchid (in my opinion)!

Mega Fanaticum and Something Enchanting

I know, I know... I said I was going to CUT BACK on tropical orchids, but at this weekend's OSA meeting, I couldn't resist a couple exceptional plants. Pictured are Paphs Harold Koopowitz (malipoense x rothschildianum) and Fanaticum (malipoense x micranthum). I call the latter a "Mega Fanaticum" because the flower is HUGE - 4.5" x 4.5". It is in a vase because the stem broke on the vendor's way to the meeting, but he left it there to show off the plant's potential. You can't tell by the photo, but the pouch is actually collapsing from old age. He said the flower had already been open for about a month - pretty much as long as these last.

Harold Koopowitz is an example of what I call the ultimate Paph hybrid - a Parvi x multifloral cross. Paph rothschildianum always produces the best of these kinds of hybrids. They have enormous flowers on relatively compact plants, with great color and form - what more could you ask for? These flowers are nearly 7" across!

I also bought another Phrag schlimii at that meeting, which I will likely post on later. So much for cutting back... maybe I will build that growing room after all?!