late starting seedlings

Jane McGary via pbs
Tue, 08 Mar 2022 08:55:38 PST
I agree with Uli about keeping seedlings cool and moist as long as 
possible. I don't grow South African bulbs, so everything I have 
tolerates at least a little frost. Here seedlings germinate in an 
unheated, glass-roofed shed, and are moved to shaded plant stands on a 
roofed patio to grow. Usually I would move pots from the stands to the 
ground and cover them during the coldest periods (here, temperatures 
below about 25 F), but I didn't during the recent few days colder than 
that and it appears to have done no harm. Some of the seedlings lost 
turgor but revived once the temperature rose. One such pot has about 20 
Tulipa regelii seedlings in it, so that was a considerable relief. I 
keep a few valuable and marginally hardy plants in an unheated garage 
under lights during winter, but they will come outdoors in the next few 
weeks. My "greenhouse" is unheated and, with open sides, is essentially 
a very large cold frame.

One odd thing about keeping the seedlings growing is that some Narcissus 
species fail to go dormant. This seems not to harm their development; 
they grow more leaves in the second season and flower in the third. I 
don't withhold water from anything that is actively growing.

Seed pots that haven't germinated are allowed to go dry (though in 
shade) in summer. I think keeping the ungerminated seeds moist (as they 
would not be in nature) might make them rot. I keep most seed pots for 3 
years, and then discard the soil among the plunged pots in the bulb 
house, resulting in a few mystery plants that eventually can, I hope, be 

Jane McGary, Portland, Oregon, USA

On 3/7/2022 4:37 PM, Uli via pbs wrote:
> Depending were you live, it is important to keep the growing 
> temperature frost free but as cool as possible for as long as possible 
> into spring. If you germinate your seed in a greenhouse it is a good 
> idea to move the seedling pots from the greenhouse to a half shaded 
> sheltered spot in the garden. Always give artificial shade for a few 
> days after the move. Greenhouses tend to warm up considerably from 
> March onwards (northern hemisphere). If this is not possible because 
> of frosty nights it is important to ventilate the greenhouse as 
> efficiently as possible and to wet the floor during sunny days in 
> order to increase humidity. Seedling pots must NEVER dry out. Once 
> growth would be stopped by a dry interval it will not resume and the 
> resulting bulbs will remain small and weak.
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