Do you know anybody growing them? Why not to ask for a cutting (could be as little as one leaf) and root it? If you have a specific cultivar in mind you could find a good selection of them at the Braeheid Gardens Ltd. in northern Alberta. They ship across Canada. You will probably have to wait for a warmer weather though, so your plants will not arrive frozen. You could also search the Net for plants exchange groups in Canada hoya plants exchange canada - Google Search
I bought my Hoya Kerrii and Hoya Kerrii Variegated at cactusenligne.ca/collections/tropical-plants In Quebec. They deliver I think anywhere in Canada only. Mine came with 2.3 x 3.5 inch leaves. Eight leaves in a complete circle. In a 6 inch pot. The picture does not do it justice. I'm waiting now for my Hoya Kerrii I ordered today with 7 other plants. If you buy $75 worth you get free shipping for as many plants as you want to buy it is free after $75 purchase minimum. They ship now. They come within 2 days of shipping. I'm in Ontario and I ordered mine Jan 13th 2020 on my last order, I got them on the 20th. But they once they send you a notification that they are shipped. You do get them in 2 days from Canada Post to your door. They don't ship in January until the middle of the month. But after January it is every Monday they ship out.
Oh and by the way. Mine already gave me 4 new leaves. I took one off on each end as soon as I got it, and out of the 8 leaves I now had 6. Then 2 weeks later I got 2 new leaf shoots on each end of where I took 1 leaf off. So I guess it will give 2 new leaves for every 1 you take off. I'm new at this and still learning. They are cute leafs half the size of a rubber tip on a pencil. They will be heart shape in a few weeks, then grow bigger from there. I keep mine under grow lights aimed at it 9 inches away 24 hrs a day when there is no sun out in winter. If sun comes out, they get 4-6 hrs sun in my window in the winter now. Then at 2pm back to the bathroom. I also have in my bathroom a portable 1 gallon humidifier on the floor running 24 hrs a day on low. If it is not raining or snowing out to make my home more humid, then I have to run it higher to keep my bathroom humidity up to %35-40. That is all I've been doing except I've misted it once a week, and watered it once in a month. I've fed it plant food of Shultz 10-15-10 for tropical plants one time half a dropper full mixed into 2 cups of water and it is still in the 6 inch nursery pot it came in.
Your very welcome. Though mine in the window with full sun is only okay now as it is not strong sun as it will be after March is over. So keep it away from the window a few feet so it don't burn. Also mist it in the morning before strong sun. You don't want wet leaves sitting in the sun to burn and draw the sun more to burn it. I don't water mine if the leaves are able to stand up without laying down or looking wrinkly some is sign of thirsty. They tell me when they need watering. When I mist them I make sure the water is not going into the pot. I want to know how much they drink and they will get their drink when I water them, not by via way of the mist. So i tilt my pot as not to water the soil top. I don't want the roots trying to come back up to the top of the pot to try drink the misty that might get on the top soil. I want my roots growing down. So I only saturate the soil and let it drain once a month. Though for a plant that new and is rooting it need the soil to be constantly moist.
I don't have any experience with growing Hoya kerrii but my Hoya carnosa likes very different growing conditions. I started it from cuttings which I got from a friend over 20 years ago. It resides in a very small pot hanging in the N-W facing window. I water it regularly every five days and fertilize it with an all-purpose liquid plant fertilizer. I prune it occasionally to keep it in the desired shape. During the hot summer days I may sometimes draw a curtain over the window in the late afternoon to protect it from the scorching sun. I never re-potted it. My thermostats are set at 15 degrees C.
Yes the sunlight through sheers is great for Hoya of any kind. Keeps them safe. Right now it is only spring and the sun is not hot or strong enough through my windows. I have a foot deep window sill I keep them on the edge away from the window. By the time the sun reaches North/West windows it is not so strong. I actually have a west/north. As my huge window is like a 1/2 bay window looking out to the the west. Then off to the right is another 2 foot wide adjoining pc of glass that lets me over see North So it helps the plants to get sun longer coming from the North, but I am on the side of the building. So I don't get the North sunlight coming through once it passes to the front of the building. Today it reached 90 on my window sill with the sun beating through glass. I had to open the window a crack and run a fan so my plants would not find it too hot too soon before they get climatized from bathroom temperature of 73.5 to 85-90 sun through glass. I will have to close over my slats quite a bit come late spring for them with a fan.
Here is pictures Hoyanut. I guess my new baby Hoya Kerri Variegata will get some cream later. One looks like it has some slight cream on it. Sundrop I'm going to buy a Hoya Carnosa Variegata next order. I did order an all green Hoya Kerrii and asked them not to deliver until it is warmer outside, but paid for them in advance as they sell out fast.
I watered my kerri when it is really really dry and let the water drain, but one of her leave still fell off. :(
Google & YouTube is your best friend to research plants. You need to have proper drainage soil for Hoya kerriis soil mix of 50% regular potting soil + 25% perlite + 25% Orchid Bark. Plants love the water to pass by their roots not to sit in wet potting mix. Only moist. Some people only feel the sides one finger deep but not nearest to the plant roots to see if moist. Best is Winter once every 3-4 weeks. Summer sun more as you see fit once a week and half or so. Forget watering until you see the plant leaf droopy or tilted more then usual flat instead of standing up perky. They are happier drier then they are over watered. You see how flat in a circle my hoya's are them 8 leaves. They lay flat because they are due for a drink. They stand up off the pots edge when I watered them. The next day perked up high.