Die back on Diospyros and Pawpaw seedlings - any thoughts

General Fruit Growing
#1

I have grown for many years Diospyros Lotus and Pawpaw from seed, they germinate well and grow well up to 15cm / 6 ins before winter.

It does not matter whether i keep them outside (down to -5 deg C / 23 deg F) or in the greenhouse (+5 deg C / 41 deg F minimum).

The vast majority start dieing back from the top tip during the winter. So by the start of spring, about 50% have died, and 40% have half died back and 10% are OK. The ones that have half died back, do shoot out, but the stem is obviously not straight then.

Any thoughts as to how I can improve survival rates please.

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#2

I can think of a few things. But first, some questions:

  • Where are you located?
  • How many months are they growing before cold weather sets in?
  • Are these in containers or in-ground

It sounds to me like they’re not getting enough growing season and don’t have time to harden off the new growth for winter. I don’t know about D. lotus, but pawpaws can take temps much lower than -5C. The upside to all this is you may be selecting for specimens that harden off early.

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#3

The same thing frequently happens to mine, but it’s never bothered me. I just prune back to the most vigorous emerging bud each spring. They always grow straight up for me, but it isn’t a beauty contest either. As they mature over the years those new leaders blend in and the trunk smooths out. I only care about the bottom 6” anyway for grafting purposes. Any low vigor seedlings get axed. The growing season is short enough up here as it is.

Like jc said, maybe the young, thin growth is slow to harden off? Make sure they stay somewhat moist as well. But your “survivability” actually sounds fine. When do you pot them and when do they start emerging?

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#4

My outdoor D. lotus had slight tip burn from around -9°C (16°F) in its first winter, but no damage at -9.6°C (14.7°F) in the third winter. I think that’s around the threshold for some damage on dormant lotus buds. We always have a long/cool fall before those kinds of temperatures, so it always is dormant. I assume it would be damaged at much higher temperatures if actively growing.

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#5

I am in the UK. This years attempt with D Lotus seeds are just popping their heads out. So probably next week they will be pricked out into pots.

Which means they are growing from beginning of May till about end of October, when the temperatures drop and leaves fall.

It did cross my mind “Any low vigor seedlings get axed” so its then a selection of the fittest.

The last few years we have had winters with only a couple of nights at -9°C (16°F), most winter days are just hovering around 0°C (32°F)

Does anyone apply extra fertilizer, apart from whats in the compost bag.

Pawpaw seeds are still not showing any growth yet for this year.