Olga didn't tell you that primula has scented leaves. The new leaves, on moist warm days, are scented of Old Spice. And it has those wing thorns. The new thorns are ruby-red and perfect triangles. The setting sun sets the new canes alight with red droplets of color. Olga, there's a primula at the MN Landscape Arboretum that's at least twenty feet wide and ten tall. In bloom, its a-buzz with humming bees. A rose that sings. I love this plant! Lovely pictures I have primula and a new 'Canary Bird' sitting in a pot.

I've given up on vermiculite. The so-called "coarse" stuff these days is always medium grade, whenever I come across it. I use bark mulch instead. If you can get it graded and delivered, that's probably your best bet, but I've had to use the bagged stuff from Home Despot - not the dyed stuff, this is Mountain Magic Premium grind. There is a good bit of wood chips in there but it hasn't caused a problem. If you have the space, aging it for a few months before use is a good idea for any bark mulch you are going to use for raised beds or potting soil. I live in a desert, there isn't a lot of choice for mulch here.

It's easier to start with relative humidity. Relative humidity means: "relative to the temperature, how much humidity (water vapor) is present in the atmosphere?" Why relative to temperature? Because at warmer temps, the atmosphere can hold more moisture. You can see at 100% relative humidity, there is twice as much water in the air at 32C as at 20C. 30 grams per kg instead of 15 grams per kg. Dew point is, as the graph indicates, this temperature of maximum absolute humidity (the amount the atmosphere can hold in actual grams per unit area) - meaning the point where the relative humidity is 100% and no more water can be held without rain starting to form. One should think of the atmosphere as a system governed by natural rules, and that system must return to equilibrium. Rain or fog are the processes that shifts the equilibrium back to this chart. You can't have more water in the atmosphere than what is indicated here. (nope, sorry, cheesy motivational speakers - nobody can give 110%, ever!) In maritime climates, relative humidity can of course be very high - near 100% when it's raining, but it's still not very uncomfortable because the dewpoint is down around 17C/62F. (and usually isn't that high in a place like Seattle.) OTOH, in the southeast, dewpoints from 70-75F or higher, are not uncommon. Even though in the afternoon on a very hot day, RH might drop to 50-60%, there's still more moisture in the air than a maritime climate where the RH is 100% but the air temp only 17C. (staying with degrees C because the chart is in C!) Notice on our chart 98F/37C at 50% humidity (green line) - very possible in parts of the south in summer - has much more absolute humidity, i.e., the actual amount of water vapor in the air - than the PNW during a May rainfall, which would at most be maybe 18C at 100% humidity. (red line) source https://en.wikipedia.org/wiki/File:Relative_Humidity.png

http://www.walterreeves.com/gardening-q-and-a/maple-pruning-to-make-taller/ So pruning forces growth in other areas....obviously there is a limitation to how much you would want to do at a time. I have noticed from personal observation of mature trees that have been trimmed on the bottom, end up adding height. I used the word probably because not all trees are the same, and some might just have no energy to grow anymore but from what I have observed, trees will grow to make up for parts that have been trimmed. http://urbantree.org/Raising.shtml This other site explains as, "Removing too many low branches shifts future growth to the top of the tree." So maybe its not a healthy thing to do? I don't know because I'm not an expert. That was just my observation.