Dear All, Mary Sue Ittner asked me to write about Dahlia species and here is my personal experience about those I grew or grow. In general I find it difficult to obtain true, non hybridized species, maybe this forum brings a welcome change to that problem...... Also I find that naming is often wrong. All Dahlias are easily grown from seed, if treated like tomato seed i.e. given an early germination and then greenhouse treatment until they can be planted out after the last frosts are over. Many of them will flower the first year but not all of them. Some may flower the first year from seed but not reach their eventual height, this only in subsequent years. In cold winter countries the tubers will have to be dug up in autumn, usually after the first frost has destroyed growth. Tubers should be stored cold but frost free and should NOT be totally dry. They may survive total dryness but will suffer. I put mine in large plastic bags only one big tuber per bag. I leave the bag wide open until the surface of the tubers has become totally dry and then close it but not hermetically. I watch for condensating water inside the bag and if this occurs I open it again and let everything dry a bit more for some days. I have had no losses this way. The emerging shoots in spring are in great danger of slug damage, even total loss is possible! Now my experience with some species: Dahlia coccinea var palmeri: This is so far the best Dahlia species I grow: around 2m tall needing no staking even in my exposed garden it has finely dissected leaves which gives the whole plant an elegant and airy appearance. The flowers are single about the size of an ordinary Cosmos but held horizontally. The colour is a bright orange red. It starts flowering in August and becomes better when the weather becomes cooler and moister. It sets plenty of seed (which I have distributed several times) some of it comes up spontaneously in the garden in late spring. The tubers are not hardy, though. It combines beautifully with Asters and late flowering Salvias. When digging up the tubers care must be taken because the tuber itself is attached to the crown via a surprisingly long thin root and thus can be easily dissected. Personally I find the ordinary Dahlia coccinea a less attractive plant than its variety. Dahlia dissecta: Only grown from seed this spring I cannot yet tell a lot: very finely dissected bright green leaves on so far low plants, no flowers yet but looks attractive. The whole plant has an almost succulent look, very nice and dainty so far but no buds as yet. Dahlia imperialis: This giant Dahlia must be beautiful in flower, but I have never seen any except on pictures. (large pink single flowers in large trusses, there is a white form, too) I did grow it for some years hoping for flowers...... but no, it was always killed by frost before. I later learned that D. imperialis is an extreme short day bloomer which means flower buds are only produced when the daily hours of light fall well below 12 hours. By the time the buds develop and the flowers open it is mid winter. I have heard that it may be possible to force this plant to flower earlier by wrapping it with black polythene sheets but have never tried this. (must be quite a job taking its size into account!) This is a very tall plant, up to 4 m in flower and would be a subject for a very large conservatory or the like in cold winter countries. It produces huge compound leaves on a straight thick canelike stem and is worthwile growing for its leaves and its tropical appearance alone. I have seen large plants in growth but not in flower in gardens on the Cote d'Azur in France where it will have the frost free winters to flower. Must be nice in California. My plants were dug up every autumn like ordinary Dahlias but I have stopped growing it. There is a good picture in the same Phillips/Rix boook as well as a most tempting picture of Dahlia excelsa. Does anybody know anything about this plant? Does it behave the same way as Dahlia imperialis, i.e. late flowering? Is it available anywhere? Does anybody know if there has been done some selection or breeding to produce a day-length-neutral, i.e. earlier flowering plant of the same stature? Dahlia laciniata: Same as with Dahlia dissecta, only grown from seed this spring. The leaves look like ordinary garden Dahlia leaves, slighty dark but not purple. The slugs had a good go at them but recovering, no flowers yet, will be taller that D. dissecta. Dahlia merckii: Often seen in English gardens in great beauty, I was not at all sucessful with it here in Germany. I assume that our more continental summers were too hot, the plant went into a strange kind of half dormancy during hot weather and did not flower only until the weather became cool and moist in autumn but then was soon cut down by the first frost. I do not grow it any more. Roger Phillips and Martyn Rix state in their excellent book on Conservatory plants that it comes form Mexico and grows at an altitude around 1600m. It is not that high and not that cool a climate there, so I do not know...... Does anybody else have similar or different experience? Related Genera: There are other genera that look similar to Dahlias and are also often tuberous: Cosmos (often tuberous) and Hidalgoa (not tuberous, the "Climbing Dahlia") The most common tuberous Cosmos probably is C. atrosanguineus. I have so far never managed to restart the tubers in spring. An attractive plant with smallish chocolate coloured and chocolate scented flowers, a bit straggly and prone to mildew in moist weather. All plants available are micro-propagated and sterile, apparently this plant is extinct in the wild. Did anybody ever have seed from this plant? There are other tuberous Cosmos species but they are not in cultivation: do prove me wrong, please.... In Bolivia I collected seed of a dwarf large flowered tuberous Cosmos of which I have two small seedlings...... It grew quite high around 3000m in 'potato growing climate' I can't tell much more yet but will keep you informed. No personal experience and never seen a plant of Hidalgoa, is it an attractive garden plant? So far my (limited) experience with Dahlia species, I thought I will give you a follow-up of this topic in early autumn when I can (hopefully) say more about my novelties. Greetings from Germany, Uli