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.