To sprout most seeds of other plants I usually use compost in the lower quadrant of my containers, topped with an inch or two of moist vermiculite. Will this formula also work for alpines, or should I have a supply of sand or grit on hand as well?

I usually winter sow most of my perennials. Some seedlings roots will reach the compost layer before I transplant them to a growing-on container, and some won't, but it's my fail-safe; fewer seedlings dry out and die during the very busy springtime season if it's in there than if it isn't.

Thoughts on this?

When I sowed alpines from seed, I used 3 parts moistened Pro-Mix and one part gritty sand. After sowing, I left the seeds to chill for a couple of weeks, either in the unheated garage or (inside plastic bags) in the refrigerator. I had mixed success. Being lazy by nature, I much prefer to buy a plant and let it self-seed.

June, when allowing the plants to self seed, which ones germinate before winter, and which lay over the winter in seed form, then germinate sometime in the spring?

valleylynn said:June, when allowing the plants to self seed, which ones germinate before winter, and which lay over the winter in seed form, then germinate sometime in the spring?

Valleylynn, the answer depends on how long it takes the seed to ripen and fall, and on what factors are needed to stimulate germination in that particular species. With thousands of alpine species that can be grown, it's impossible to give a comprehensive answer but this is probably a decent general guideline.... Species with simple germination - that require only moisture and warmth - will germinate at any time when enough moisture is present and it's warm enough. Species whose seeds require stratification (a cold period, or alternating periods of cold and warmth) will, generally speaking, be more likely to germinate in spring.

Any plant that's capable of producing viable seed will self-seed in the right conditions.

The most prominent self-seeders in my rock gardens - surprisingly few, really (the tufa beds are still fairly recent and it takes time) - are not problematic (I'd turf ones that were, or move them out into regular soil where there would be more competition). A few that spring to mind:
Campanula hawkinsiana is monocarpic so I'm very pleased that it self-seeds:

Saponaria pumilio gently self-seeds around itself:

Lupinus caespitosus var. utahensis - good thing it does self-seed because I'm still looking for the trick to finding conditions where a plant will live more than two years:

Dianthus glacialis seeds a little around itself:

Campanula saxifraga blooms very heavily and long and so produces quite a bit of seed - a little weeding is necessary now after many years:

Hypericum aviculariifolium ssp. uniflorum - another one that so far has been monocarpic for me, although I think it should be perennial:


Campanula thyrsoides is an alpine meadow plant but it's not in my rock gardens (too big); it self-seeds reliably - also good because it's monocarpic:

Great information, Lori! Your knowledge is awesome.

Aww, shucks... Thanks, June.
Sedum pilosum (now Rosularia pilosa) is another monocarp that depends on self-seeding. I have self-sown seedlings in the garden but it'll take a while yet before it will be clear if it's self-sustaining:


The seed starting mix I use is home-made and imprecise (because I'm lazy!) As time has gone on, I've gone to using more and more sand and grit versus humus (which is purchased potting soil). It also depends on what I have at hand. A typical mix these days would be equal parts sand, fine grit and potting soil with often a half portion of perlite thrown in. It's a lean-ish, fast draining mix - due to the sand and grit, a tray of seedlings is quite heavy. I re-use the mix from year to year (I knock a lot of the soil off seedlings in to a pail when I plant them out - planting space between rocks is often limited). I keep the collected and recycled alpine potting soil in Rubbermaid totes in the basement. This works here for me - if you have problems with damping off, it may not work for you.

Thanks, Lori.

Are yours typically started outdoors or inside under shelter? Does it matter for most? I'm not usually bothered by damping off, but I'd assume that's because I start any seeds that I can outdoors.

chelle said: I'm not usually bothered by damping off, but I'd assume that's because I start any seeds that I can outdoors.

Chelle, that's great advice for those plagued by damping off to start seeds outdoors.

I start the vast majority of my seeds indoors under lights because winters are long here and I want seedlings to be a reasonable size prior to planting out (and I know my standards for "a reasonable size" are much lower than those of many others who would grow seedlings on in pots at least until the next spring or even longer). Starting them indoors under lights, I get germination long before they would be able to germinate if winter-sown in containers or in open flats outdoors, and hence more time to grow them on.

Thanks again, Lori.

Sometimes I really wish I had space for an indoor light set-up, but since I don't, I'll be content to wait.

Thank you Lori for all the information. It is very helpful.

My seedling mixes have become more lean as I have become more experienced, also. Now I use probably about half sand, 1/5 potting mix and the rest varied sizes of grit. And more often now, I'll put a quarter inch layer of almost pure regular potting mix at the bottom of the pot for two reasons: 1) to prevent the excessively sandy soil from falling through the holes, and 2) as a reservoir of moisture for the mineral soil above. I am also imprecise in my mixing methods, and exact proportions are never the same. Depending on the seed, I use a surface grit layer of grit, on up to a cm deep.

In respect to the leanness of my mix, yes, I think I am on the extreme end. For myself, I seemed to have found that since I mostly germinate seed outside with the normal season, with more moisture retentive mixes I would sometimes get seed germinating at the edges of the pot, rather than all over the surface. This I attribute to the faster drying of the medium at the periphery.

Leftwood said:... I'll put a quarter inch layer of almost pure regular potting mix at the bottom of the pot for two reasons: 1) to prevent the excessively sandy soil from falling through the holes... Depending on the seed, I use a surface grit layer of grit, on up to a cm deep.

I do most of my seed-starting in the little 2 1/2" square by 3 1/2" deep pots that alpines are often sold in; the bottom of these pots is open with only a little plastic cross across the center. Soil is kept from falling out by a little square of metal window screen or plastic mesh set in the bottom of the pot. I've started using a surface layer of grit (or sand) also - it seems to discourage the growth of algae* very effectively.

*Edit: Sorry, I should have said "moss", not "algae".

Leftwood said:...with more moisture retentive mixes I would sometimes get seed germinating at the edges of the pot, rather than all over the surface. This I attribute to the faster drying of the medium at the periphery.

Interesting... I often see that too with indoor growing and constant moisture. In my own case, I figure it's due to washing the seeds to the pot edges in the initial watering, as I often sprinkle the seeds directly on top of the soil mix, with no soil or only a little sprinkling of soil overtop.

So, algae growth with these types of seedlings must be quite detrimental, in and of itself?

[edited to correct spelling typo]

Sorry, I should have said moss, not algae! Well, I think it might possibly be detrimental, though I'm not sure. It can form a layer across the soil surface that I imagine might possibly prevent a cotyledon from pushing through... ? Pots with significant moss growth are usually ones where germination is really, really slow or has failed... so it could be I'm mixing up correlation (presence of moss in "dud" pots) with causality (the moss actually having something to do with the failure of the seeds). In short, I don't know...

Me, either. I hadn't had problems with it damaging anything in the past, but wasn't sure about these new (to me) plants. I won't sweat the small stuff then; thanks!

growitall said: I've started using a surface layer of grit (or sand) also - it seems to discourage the growth of moss very effectively.

For me, liverworts are the worst problem that grit alleviates. Regarding moss physically inhibiting seed sprouting, I have no real experience with alpines. I can say that I have had woodland seed sprout through moss, but can't say if other woodland seed that never sprouted was due to moss or not.

Leftwood said:...with more moisture retentive mixes I would sometimes get seed germinating at the edges of the pot, rather than all over the surface. This I attribute to the faster drying of the medium at the periphery.

growitall said:Interesting... I often see that too with indoor growing and constant moisture. In my own case, I figure it's due to washing the seeds to the pot edges in the initial watering, as I often sprinkle the seeds directly on top of the soil mix, with no soil or only a little sprinkling of soil overtop.

I did think about that, but for me I think its unlikely, since I always have grit covered surface.

My first batch of specialty seeds are here! I can't wait to begin winter sowing them. Not that anything will happen with them anytime soon, but at least it's something gardening related to do when it's too cold to linger outdoors.

One plant in particular's sprouting recommendation is to grow it on @ 40 degrees for three months to acquire a proper foundation, and I can't think of any way at all that I can simulate that environment here. So...it's going to be a fun learning experience.

Chelle ~ What seeds did you aquire, and where did you get them? A seed exchange, or did you purchase them?

These are some of them, Evelyn. http://garden.org/thread/view_...

Some I ordered online, and some will be coming my way from trades with others. I placed orders with two seed suppliers this year that I'd been wanting to try for years; Alplains and Plant World Seeds. The Alplains order just recently arrived, and the other hasn't as of yet.

chelle said:
One plant in particular's sprouting recommendation is to grow it on @ 40 degrees for three months to acquire a proper foundation, and I can't think of any way at all that I can simulate that environment here.

You mean after germination, right? I find this to be a very tough one too, the problem being finding a place in this climate that is cool but consistently above freezing, and also with light. (Dark, I can manage easily in our cold room, which I use for stratifying. However, putting a fluorescent light setup in the cold room would cause the water lilies and tender roses that are overwintering in there to start growing, which would not be good.) An unheated solarium or porch might be the answer... if one had one. Which particular plant is it? Maybe winter sowing will provide enough of a cool growing period, one can hope.