Diary Entry No 25 - Seeds!
When I started growing alpines from seed, the popular advice was to sow in the autumn as alpine seed needs 'vernalising' or 'stratification' (exposure to cold). Many people do follow this standard regime and sow all seed in the autumn outside and leave it for up to three or four years. Over the years I have experimented with different seeds and different regimes and found some successes and many failures.
There are lots of factors affecting success and failure. One problem is that weather conditions necessary to germinate a particular seed don't necessarily happen that year. Another issue is that some seeds need two or more seasons of differing weather (in the correct order!) to germinate. I have used the fridge to mimic a cold season and indoors to mimic a warm one, sometimes with success, but it needs discipline to follow the necessary procedures. I do try different species each year which need different conditions. Another personal factor is the time I have available at different times of the year, sometimes very little to spare. And another issue is that mice eat the seed so I don't know what might have happened even if I had got it right!.
My practice over the last few years to suit my “available” time has now settled down to this pattern. These timing are not necessarily what I would recommend to others who may have more time than me, they are just what I personally do, with usually acceptable results. The following list shows my own personal interests and seed I have had experience with over the years:
Cyclamen: Sow in November in a warm situation (indoors). Cc hederifolium, graecum, africanum and persicum will germinate in a month. Other species will follow. C purpurascens is a mystery, I am still experimenting!
Alpine dicots (e.g. saxifraga, primulas, all true mountain alpines): Sown in January. The first to germinate are usually members of the family Brassicaceae (hence the expression about mustard and cress!).
Monocots: sow before Christmas, or if not, then in April. There will be some germination in May or June, and some will germinate the following year. It may be better to sow in the autumn but I have never got time. Often Narcissus germinate with me in May or June. Juno Iris, Colchicum and Alstroemeria definitely seem to germinate after frost. Other varieties I have not tried enough times to establish a pattern.
Warm germinators: e.g. species aquilegia (for me a secret passion, known to few): sow in April
Fine seed needing special treatment (e.g. gesneriads, ericaceae, ferns): Sow in April. Sterilize compost with boiling water, cool, then sow seed on top, cover with clingfilm and keep in a warm shaded position.
Epigeal germinators: (Paeonia tenuifolia and some lilies): Sow in April or May. Epigeal means that the first thing to appear are cotyledons above ground. I have also had success sowing these in the winter, either way, germination can happen a few weeks after sowing.
Hepaticas and other woodland plants with ephemeral seed (e.g. Jeffersonia, Eranthis): Sow in May. These are woodland species (and in Deno’s terms) 70 - 40 germinators, that need summer, then winter in order to germinate. These must be sown fresh and they will then germinate the following February or March.
Hypogeal germinators: (most Paeonia and some lilies): Sow in May. Hypogeal means that the roots develop first in the autumn, and then in the following spring appears the first true leaf (not a cotyledon).
Arisaemas: Sow in May. They will germinate quite quickly when sown at this time of year when it is warm and will continue to grow until around November when they will go dormant.
Although I am sure there will be plenty of opposing views, this regime seems to work for me and suits my situation. Clearly those I have tried the most are the genera I have a particular interest in, and there are plenty of genera I have not enough experience of to draw proper conclusions!
Successes so far this year
Lilium lophophorum and Trillium rivale, both from wild collected seed, both germinated well. The trillium was sown last April and has just germinated; this lily is clearly an epigeal germinator as the picture shows (the first growth is above ground). This pot was actually sown in December and germinated very quickly as this species usually does.
Various monocot seeds do like a cold period before they germinate. Over the last few years I have often had poor germinaton of Colchicums, Juno Irises and others. However, I found that during the spring of 2009, after the hardest winter for several years, several of these pots germinated after a wait of three or four years. This year, also following a hard winter, I have had a good germination of these monocots.
Erythronium and Crocus, both from wild collected seed, both sown last April, have germinated well
Asarum marmoratum, (below) wild collected seed, sown last April, just germinated, although you will see from the pot that one seedling germinated last autumn and has developed true leaves.
Hepatica from my own seed, sown last June. Several pots of hepatica seed have just germinated, as they reliably do as soon as the weather starts to warm up, as long as they are sown fresh in May or June and left in moist conditions through the winter.
Please make any comments about this Diary Entry in the discussion thread: