Andrea Locke wrote:I am interested in advice on several aspects of paw paw cultivation.
(1) Producing paw paw fruit. I live on a small island off Vancouver Island on the west coast of Canada. The winters here are mild (usually rainy from October through April with temperatures dipping to just above freezing, with 1-3 weeks of snow and freezing temperatures) so I am not concerned about winter survival, but summers are cool and I'm not sure there is enough heat to reliably ripen the fruit. The summers here are long, dry, and sunny, but daytime temperatures are often only about 20-25 C (about 70 F) with maybe a week getting up closer to 30 C (about 80 F).
I know that at least one fruit aficionado on Vancouver Island has them successfully fruiting in his backyard garden (Bob Duncan of Fruit Trees and More) but he has them espaliered against a south-facing wall in an intensive fruit tree situation. I am hoping to produce fruit with paw paws planted in the understory under sweet chestnuts, similar to the mixed chestnut and paw paw setup that they are using at Red Fern Farm in Iowa. However, I am concerned that the shading effect of the chestnuts might reduce the heat units to the paw paws even more. In their native habitat they do well in shade, but it is a heck of a lot warmer in summer there. Do they need a minimum temperature to ripen, or a certain cumulative number of heat units?
(2) Overwintering very young seedlings. I bought seeds from England's Orchard in Kentucky last spring and asked for the shortest-season seeds they had. So far I have about a dozen that have germinated and are growing outside in pots. They are pretty small, only a few inches tall and with about 4-6 leaves. I am not sure whether I should leave them out in pots for the winter, perhaps in my unheated 'greenhouse' (it's one of those semi-opaque garage shelters that I use for tomatoes and other plants that need more heat or extended season), versus bringing them into a cool room in the house. I wonder if the latter would be safer, and maybe even allow them to grow a bit more over the winter. So far they have not dropped any leaves for the winter and it is about 7-10 C out there (45-50 F).
(3) Seed germination. More than half of the seeds I planted this past spring/early summer did not germinate this year. I'm guessing maybe a 20% germination rate? They were stratified by the grower so in theory should have been ready to sprout when I got them. Someone at the NNGA/NAFEX meeting suggested that they might need warmer germination temperatures than what I had here (I had them in the warmest microclimate available outside, but see note above about summer temperatures). Should I leave the unsprouted pots outside overwinter for another winter of stratification in hopes of some sprouting next year, or if they have not already sprouted are they basically done? I don't think they dried out at any time, not sure what the normal germination rate might be or how long the seeds might last following planting. Another option would be to bring them into the warmest spot in the house, which would be near the wood stove, in hopes of getting enough heat for a successful late germination of the non-starters.
Thanks in advice for any insights or suggestions. - Andrea