Sunday, June 4, 2017

Cold Hardy Osteospermums

These South African daisies are commonly grown as tender annuals in the northern states, but there are cold hardy species and selections.  "Avalanche" is a particularly good one worth tracking down.  I suspect it is a white selection of the normally lavender pink O. jucundum.  I have both in the gardens now and although the jucundums did suffer a bit this winter, oddly since it was milder than last winter, they are back in bloom along with the 'Avalanche".  They will produce seeds if multiple clones are present, and both are easy to propagate by severing and replanting pieces from the stems that root as they grow outwards.  I usually put some coarse sand over some of the stems as temperatures drop and sometimes cover them lightly with wood chips to minimize dieback during cold winters.  If the stems survive they resprout quickly when spring arrives.  They bloom throughout the growing season but are especially spectacular right now.  I think the very mild and rather strange winter, with arguably the worst weather in March (!) was to their liking so they are making lots of flowers right now.

Seeds of Osteospermum come in two types, one somewhat triangular and nut like, and a flatter rounded seed.  The latter is probably primed for faster germination whereas the other is supposed to remain viable for longer, so the plant hedges its survival strategy by having two different types of seeds.  However I havent really noticed much difference in germination of either, if anything the first type of seed seems to be viable more often than the flatter ones.  I should get a good seed crop from the area where both jucundum and "Avalanche" grow together, but "Avalanche" alone rarely sets seeds.

Sweet Williams (Dianthus barbatus)

This old fashioned biennial, or really perennial in my experience, is one of the highlights of the season here.  I grew mine from seeds, and that really is the only way to do it as the newer "sweet williams" that come in packs or pots are quite inferior to the real thing.  They may bloom their first year but they don't have the dense flower heads and wild array of colors and patterns of the real thing.

They do need to go through one winter to flower, and while some plants may be short lived perennials they usually do make vegetative growths at their base which become flowering stems the following year.  I suppose one could separate and root these if one had a particular clone that was especially prized.   But allowing them to seed will give a wide variety of zoned, spotted, and/or bicolored flowers in colors ranging from white through reds and red purples.

Cold hardy Crinum bulbispermum

Right now many Crinum bulbispermums are coming into bloom and/or spiking in my gardens.  I have a number of plants grown from South African seeds from the Blomfontein area, as well as others from US sources.  The latter may contain other genes in them, as crinums are a staple in the South and seed freely when happy.  True bulbispermum is supposed to rarely if ever offset, but they do produce lots of large green seeds which must be sown fresh.  Those seeds also take time before they reach flowering size.  Mine have taken anywhere from four years or more to do so, but now most of the first batch are flowering.  A few of them did flower last year, but now all seem to be flowering sized.  This is probably one reason they are not commonly sold in nurseries, for they are not an ideal pot plant, taking a rather long time to reach flowering size and not growing all that well in pots to begin with.  I grew the seeds in large pots until the bulbs were more or less tulip bulb sized, then planted them deep in the soil to protect them from freezing.  They have survived both harsh and mild winters, and pop up back into growth quickly after the last frost date has passed.  They are especially profuse with bloom this year, and if they do as they have done in years past, more spikes will follow sporadically during the summer and even fall.

The blue green wavy leaves are diagnostic for this species as is the not so wonderful floral scent.  There are other crinums that give off a wonderful fragrance but this is not one of them.  Fortunately it can and has been used to create other cold hardy crinums some of which may be better in the fragrance department. 

Even without flowers the foliage has a commanding presence in the garden.   Needless to say no one else in the neighborhood grows these, nor anyone else in my state as far as I know.  Besides the trouble of finding them in the trade, the other reason they are not widely grown up here is because most gardeners who are aware of crinums probably think they all are tropical plants, but that is not the case with this one. One of the neatest things about gardening is trying plants that are "not supposed" to survive in your area.  Sure, many might not survive, but many will, and horticultural rule breaking makes for some of the most interesting gardens in my view. 

Ornithogalum magnum

I really like this different sort of Ornithogalum from Georgia, as in the Caucasus, not USA.  It forms tall spikes that flower rather late for a spring bulb, just as the foliage is dying back.  They are quite graceful among the other flowers in my garden right now.

It does produce seeds which can be used to propagate more, but I haven't really tried to grow more intentionally as the bulbs are quite cheap in the fall online bulb catalogs.  Sowing them in fall as with most spring bulbs should work, and germination should commence the following spring.

Swathes of Senecios

Senecio is an overly large genus spanning just about all the continents, except Antarctica of course. No doubt it will (or has?) be broken up into separate genera by the molecular cladists.  However at this time one of the peculiar things is that in a genus of overwhelmingly yellow flowered plants there are several from the southern hemisphere that are shades of purple.  I know of at least one species in South America, but the ones I am most familiar with grow in South Africa.  Three cold hardy species find my gardens very much to their liking, and all three are blooming now.  The first species, Senecio macrocephalus, is the lowest growing of them, and also puts on the briefest show.  It is in peak bloom now, forming a sea of color in the front garden and also in spots in the back gardens.  Flowering lasts a few weeks and soon copious amounts of seeds will set.  These fly in the manner of dandelions and germinate quickly to start more plants which will add to next year's show.   The fleshy leaves lie on the ground in a rosette and are wider than the other two species I grow.

Senecio polyodon grows in boggy areas in the Drakensberg and was the first of the purple South African senecios to be introduced into the US.  Panayoti Kelaidis of Denver Botanic Garden collected it on his first expedition to S, Africa and it remains in cultivation in the US and Europe to this day, though I would not say it is common in the US.  It produces smaller flowers than S. macrocephalus on slightly taller stems.  The foliage is not as succulent either and is long and narrow by comparison.  It is beginning to flower and will flower for well over a month if conditions are suitable.  It will also self seed, but not as robustly as S. macrocephalus.  In fact I have to rouge out seedlings of S macrocephalus to keep it from outcompeting S polyodon.

The third species is not yet identified, but came from the Tiffindell ski resort area of the Drakensberg so I refer to it as Senecio sp. "Tiffindell".  It is the only one of the three species that is stoloniferous in addition to self sowing.  So it is able to grow into a large patch rather quickly.  It flowers quickly, within a few months from seed.  Flowers are bigger than S. polyodon but a bit smaller than S. macrocephalus.  It does a mass flowering right now, with sporadic blooms appearing the rest of the season.  It is at least as vigorous as S. macrocephalus in my garden, and while it might not out compete the latter since its leaves are not as large, its ability to spread by thin stolons does give it an advantage over the other two species.

All three species are readily grown from seed and appear to be quite cold hardy.  They do not appear to be hybridizing as far as I can tell, though they are rather similar in appearance and in peak bloom time. They also like moist soil, though they do tolerate some drought in summer after their main flowering period.  Lately it has been quite cool and rainy, in fact this is probably one of the coolest and wettest springs I can remember, and all three senecios are doing extremely well.  The mild winter also resulted in practically no dieback of the foliage so that helped too.  None of them like really hot weather, though they don't suffer much here in New York but I am not sure if they could deal with the summertime heat of places like North Carolina. As with most Asteraceae it is best to grow a few plants from seed to ensure that fertile seed is set as many Asteraceae are self infertile. Individual plants of these senecios may not live beyond a few years so having seed as a backup (or seedlings coming along, which will happen if there is bare ground nearby) is the best way to ensure that one will be able to enjoy swathes of senecios for years to come.

Thursday, May 25, 2017

The Weird Dogwood

Yes there is a strange dogwood in our yard.  I would have had it cut down as it has dieback on one major limb and is past its prime, but having seen it flower I knew it was something special so it was spared from the saw.  In fact I had some nearby hemlock branches cut so it could get more sun, and I do water it when it gets too dry, as was often the case last summer.

 The flowers don't quite open, and most closely resemble a subspecies of Cornus florida that occurs in Mexico, ssp urbiniana.  Yet I find it hard to believe the previous owners would have gotten their hands on this much sought after subspecies.  They did like pretty bushes and planted a lot of azaleas and rhododendrons, most of which remain, along with forsythia, lilacs, andromeda, and other common shrubs, some of which I have eliminated or reduced. But if this dogwood is not urbiniana it must be a mutant which coincidentally results in the same caged flower appearance as ssp urbiniana. It is attractive in a different sort of way, and I am trying to propagate it.  Cuttings that I took and also brought to NYBG failed, so I am trying to ground layer it.  I also have pots of seedlings coming along but as dogwoods are self sterile from what I read, I assume the seedlings have a regular dogwood father.  What I don't know is if the caged flower trait is dominant or not, so I won't know what the offspring will look like until they bloom, which could be a long time.

The tree has been making more flowers since I had the hemlock branches in front of it removed.   I still need to remove a dead limb from the tree, but overall I think it is liking the renewed attention it is getting since we got here


Many flowers eventually open but never flatten out like normal dogwoods, and all the bracts have that odd keel or fold in their middle.

Odd indeed but I like it.

Its Dianthus time again

A minute cushion forming species which I got from rock gardening friends who got it from Wrightman Alpines.  It was given to me as a small rooted cutting and has turned into a perfect "bun" in a couple of years.

This one is an interesting shade of pink which I rather like

Its that time of year when each day brings new surprises.  Despite the often less than favorable rainy/cloudy weather this spring, the dianthus in my gardens have done well.  No doubt the mild winter helped, and also the generally cool spring temperatures tend to favor them.  Most of what I have, and there are many dianthus here, are grown from seed from the exchanges (NARGS, SRGC) and my own seeds from the ones I grew in the school garden some years ago.  A few linger on at school but the voles seriously culled their ranks during one of our snowier winters a few years ago. I also haven't been as diligent at weeding the school gardens as I was before we moved to this place where my gardens take up much more of my time than they did in our prior residence.  When one gardens on over half an acre (minus the footprint of the house and driveway, but counting in some of of the patios as there are quite a few things that really do well in the cracks between bricks or slate) it takes a lot of time and effort.
Many of the dianthus pictured here and others came from left over NARGS seeds which are redistributed to the local chapters after the two main rounds are done.  So few people these days seem to be willing to try and grow from seeds, and indeed many seeds can be challenging or take time to produce mature plants, but dianthus is not one of them.  Dianthus seeds germinate fast, and need no special conditions apart from reasonably mild temperatures, decent soil and moisture.  They grow quickly and often flower their first year, and certainly will do so their second year.  They do have certain demands, for one they must have good sun exposure, and also they need good drainage.  In the areas where I have planted a number of them I have amended the heavy soil we have with coarse sand ("road sand") which they seem to like.  They cross readily and a myriad of different flower colors and patterns emerge, as well as fringed petals on some.  They also smell wonderful, and if you get a particularly nice plant from seed, it can be propagated easily from cuttings.
Few pests bother them apart from herbivorous mammals.  Voles can be especially destructive during winter if there is a long period of snow cover as they munch through the cushions and line their trails with dianthus leaves.  Deer will sometimes bother them but most of mine are in the back where posts and mesh keep the deer out and in the front I use Liquid Fence every few weeks to repel the few deer that are in this area.  Dianthus also don't like a lot of organic matter near them so don't put mulch around them, they prefer gritty soil that is not too high in organic matter.
There are some other species that will flower later, among them D. amurensis with blue-lavender flowers and Dianthus taiwanensis (or a Taiwanese form of superbus) which I grew from seeds I collected in Taiwan.  The latter flowered profusely their first growing season, and all of them survived the winter in great shape, and are in bud right now.  I also have some cultivars from Santa Rosa Gardens which are more carnation like.  They tend not to form seeds and are a bit fussier than the seed grown singles.  In addition I grow the Chabaud carnations, they are easy from seed and flower their first year, and some usually survive winter, especially if it is mild.