I've made a hypertufa alpine planter, and I decided to put an Edelweiss plant in it (Leontopodium alpinum). I've read that it likes rather alkaline soils with some sort of limestone in it. One soil mix I've found on the web is:

5 parts grit
1 part compost
1 part crushed limestone

I can't really find any sort of limestone in garden centers except for something called "gardenlime". It says it is "derived from dolomite lime" and that it is "the finest grade of pelletized, dolomitic limestone available." It is a bunch of small, black/gray pellets. Can I use this?

I realize that the concrete I used to make the planter is also very basic (alkaline), although I am planning on soaking it in water for a few days to reduce the pH. Although, will it be necessary to use lime pellets if I don't wash the trough?

Thanks a ton,
-Ben

Crushed limestone may be as close as your front door. Single color tan gravel driveways are usually made of crushed limestone. The paver base that you would buy from a place like Home Depot for underlayment of patio bricks or retaining walls is crushed limestone too. Realize that these would also contain very fine particles, and seiving or washing to get the dusty stuff out will help keep your final soil mix porous (as edelweiss and other alpines like).

The pelletize limestone would be usable, I think, too. But I think I would only use one-fourth of a part. I am not sure how fast it would react in the mix.

I'm not completely sure as to how long to soak it for; would a few days be alright? The trough still isn't done curing though; it's only been about a week and a half. I'm going to probably let it go for 3 weeks.

Yeah, I think I saw paver base at the store; it looked like what I would expect crushed limestone to look like. The pelletized limestone apparently reacts slowly and "doesn't pose the hazards associated with hydrated lime."

Sorry for all the questions. I'm new with this kind of stuff. I just was also wondering if 3"-4" of depth is enough for something like Edelweiss? And would Sempervivum species tolerate the added lime?

Thanks,
-Ben

Some people don't soak their troughs at all. Others do it for a week, changing the water every day. It's really not that important if you are going to plant with lime loving plants. I would at least do a few days. It will keep the possibility of residue forming under the planted troughs (on you deck, for instance).

Minimum curing is 2 weeks, and the longer it cures, the stronger it will be. Curing does stop when the trough dries, but the slower it cures, the stronger it will be. Cement (and hypertufa) cures even when wet (or under water), but keeping it moist will slow the process. I keep mine sealed up and moist in a bag during curing. If I make a trough in the winter, it stays sealed up and moist for more than a month.

The pelletized limestone apparently reacts slowly and "doesn't pose the hazards associated with hydrated lime."

Correct. But I suspect the lime pellets will still react a lot faster than limestone itself (although there are different kinds of limestone too).

Alpines in general, including edelweiss, naturally grow roots deep in the soil compared to topgrowth. Four inches would not be deep enough for an in ground garden. But in a trough, plants will adapt, even though they would prefer a longer root run. Sempervivums are native to limestone outcrops, and prefer alkaline gritty soils, althought they are very adaptable.

I've heard that putting some vinegar into the bath can help neutralize more lime, so I might try that for one of the days that I soak it.

I've got another question, regarding the soil mix I posted above:

When I put a small sample of it together, it looked like it wouldn't hold much water at all. I used sharp #20 grade pool filter sand for the "5 parts grit", and it just seems like too much sand. Since my trough is mainly for Sempervivum, and the Edelweiss is just a last minute thought, would a 60/40 mix (grit/compost) be ok?

Thanks,
-Ben

Regarding your growing medium, it is recommended that you use different sizes of grit, rather than all one size. However I have use only sand for my grit component seemingly without detriment. I can't say for sure, but it works. Larger sized grit allows for even better drainage, which, even compared to just sand, is advantageous for alpines.

Sempervivums are very adaptable to all kinds of various soils. They will grow just about anywhere that allows for drainage. But not so for edelweiss. It will need the lean, mineral soil. Below is a link to a trough of mine with soil that was too rich. This is one thing that can happen - overgrowth. With edelweiss, it would probably just grow too lush and limp, with few or no flowers.

You could probably get away with
2 parts compost
5 parts grit
1 part crushed limestone

Yes the medium looks very pourous, un-water retentive and with no nutrient value. That is how it should be. You can always give it a little fertilizer if you need to, but you can't do the opposite once your plants are planted. In years that I do fertilize, my alpines get one fertilizing, in early to mid spring, and nothing more for the rest of the season.

Dunno if it's healthy or not, but if it makes it through the winter I'll be pretty pleased.

Speaking of winter, can the plant tolerate being exposed in a plastic pot outside during a zone 6 winter? Or would it be better if I put it into my garage?

Thanks,
-Ben

The plant also looks like it is planted somewhat high above the soil, compared to regular plants. This is also good. Alpines like their necks "high and dry". It is one of the most common mistakes with newer alpine gardeners - planting too deep. But you can put a topdressing of gravel, pea rock, etc., even perlite if you like. Actually, it would be advantageous, as most alpines like lots of sun but not hot temperature, especially the soil.

For winter, the best thing would be to sink the pot in the soil on the north side of your house where it will receive little or no winter direct sun. Second best would be east side, or somewhere else where it is shaded in the winter. This will be your next big hurdle to overcome in edelweiss culture. Like most alpines, a wet winter (called winter wet) spells death for edelweiss. Of course, they need moisture, but not too much. Another reason for the excellently draining soil.

Barring those possibilities, I think you could keep it in the garage, but only for your coldest 2 months of the year, and no water unless you are sure that is the cause of wilting. When the ground freezes, of course watering will do no good, and in fact will cause problems. The rest of the winter, keep it outside so it gets good air circulation, and in the shade.

Yep, those longs leaves were there before I transplanted it. Its compost is mostly perlite and sand. The reason it's kinda high up outta the soil is because I think some of it washed out, but I'll leave it like that now I guess or add some more stuff like ya said.

Ok, yeah I figured putting it in the ground would be best. But, why does it want shade in the winter? It's not like the plant would move on its own naturally. Or, do alpine areas get shade in the winter? We have plenty of snow (usually at least 1-2 feet).

Also, another question: is it bad for the plant to keep it in this plastic container for the rest of its life? I've read that that can cause the plant do deteriorate, although it is a very deep pot (around 8").

Also, do you think that there is a good chance that this plant will flower in spring? I can't wait for the flowers, as half of my family is German.

Thanks again,
-Ben

As alpine like edelweiss hate hot temperatures (and humidity) of our lowland summers, you may find it would prefer some midday shade in summer too.

Shade in the winter will help keep it dormant (less temperature fluctuation), and the snow that covers it dry (not melting). If all you get for the whole winter is 1-2ft, that's not very much. Not knowing where you live, 1-2ft means bare soils for parts of the winter, when soil can become excessively dry, and be exposed to wide temperature ranges. The blanket of snow is meant to keep the cold in so it doesn't thaw, and at the same time keep the soil from getting too cold.

Another characteristic common to nearly all alpines is deep rooting. Many will send down a few or even just one single root down 4-6 inches before it even starts to branch. Yes, deep pots are very advantageous. I don't see a disadvantage to using plastic pots, except that they might heat up more quickly in the sun. Warm soil is abhored by mountain plants from the Alps. If you have an option, stay away from black. Even so, edelweiss along with many other plants would probably be happier in the ground because of the moderation of temperature. On the other hand, other environmental factors might not be as favorable.

I would guess that your plant will bloom next season, depending on its survival through the winter. As for myself, I never thought edelweiss flowers were all that pretty, but their sentimental value is telling. So then, I assume your ancestry is from the very south of Germany, as most of the country is not mountainous. Good luck!

I would plant the thing in the ground, but our soil is heavy and full of clay. I've heard of some people having success in similar areas, but I am sort of too scared to try.

My German family is mainly from the Rheinland, I think. But my mom says that everyone in Germany knows of the significance of the Edelweiss.

Mainly I'm just fascinated and infatuated with its history and lore. And I agree, that flower is pretty dang ugly. But, I think that it has a certain charm, like a small face peering back up inquisitively at whomever is about to pluck it.

-Ben

They all have made it through the winter well. The ones that I put into the ground for the winter have been under snow and ice for several months, and only with this warm weather have I been able to view them. They have formed incredibly small, white, fuzzy winter buds under their mats of dead leaves. I almost couldn't see them, and thought them dead (I will try to get pictures of them soon). But the ones I've actually planted into the ground instead of pots have started growing from their buds, most likely from being exposed to sun and water. So, I've moved the potted Edelweiss to the same location to wake up and hopefully, hopefully flower.

-Ben

Should I divide it? Or is it okay as it is?

I can't wait to see the flowers.

-Ben

Mainly, I'm just worried about whether or not I should divide it. The only reason I'm concerned is because it seems to be doing so well, and I don't want to hurt it, and also because I would need to buy a whole nother bag of sharp sand.

Thanks
-Ben

It's interesting and a little disappointing, but the plant in the ground has a much whiter color and looks a lot healthier than the one in the pot. I'm glad that it's doing well, but I just wish that the one I've been actually trying hard to grow would be the healthier one.

Anyways, I planted them in pots and in the ground as an experiment, and both are going to flower, so I'm not really complaining. I'll get pictures when they open up. :D

-Ben

And here's flowers from the one in the pot:

Well I guess they don't like pots so much...:P

-Ben