Pre-cooling bulbs

Asked July 6, 2019, 7:25 PM EDT

I've just ordered some bulbs for fall delivery from a place in Connecticut. They indicated that since we are zone 8 here in Portland, the bulbs will need to be pre-cooled? Really? I've never done that in the past...What say you?

Multnomah County Oregon bulbs stratification flowers: annuals and herbaceous perennials

3 Responses

https://hort.uwex.edu/articles/forcing-bulbs/
We have to make some assumptions here because you do not indicate whether you are planting garlic, shallots, or onion sets or are planting flower bulbs such as tulips, narcissus, etc. If you are planting food items, the recommended date is early October. The bulbs may sprout, but winter cold generally keeps the green tops small while the bulbs focus on growing roots. In spring, warming weather will cause the tops to start growing. At that time you fertilize them and keep them growing strongly until harvest.
. Most spring flowering bulbs can be planted up from late September until December. If you are planting tulips, you should pre-chill them at 48 degrees (refrigerator temperature) for at least 6 weeks before planting. Fertilize spring flowering bulbs with bone meal or other high phosphorus fertilizer when planting. Do not expect top growth until weather warms in early spring (February for narcissus, later for tulips,) At that time, fertilize them with a complete fertilizer, keep them watered if it does not rain, and wait for the beautiful show! Please let us know if you are planting something other than those mentioned above, as there are other "bulbs" such as lily bulbs and iris rhizomes which require different handling.Thanks for using Ask an Exper
Generally speaking, spring flowering bulbs that have been grown in pots can not be successfully planted outdoors for future bloom. It's best to dispose of them after the flowers have faded. Hope this helps

Thanks for the info! I am planting flowering allium, tulipa turkestanica, and the tiny species tulips. I ask the question because I’ve never chilled the allium or the species tulips and had great luck w/them!

I’ve never planted the turkestanica before, so want to be sure that the tulips I’ll be planting in the fall will do well…Not sure when the bulbs will arrive, but will check on that. Please let me know whether the species tulips should ALSO be pre chilled or if it’s just the turkestanica…

Many thanks,
Dawn Nowak

Well, it's a bit hard to determine why the recommendation is to pre-chill the bulbs but my take on this is that they are not distinguishing Zone 8 climates like the SE United States from Zone 8 in the Pacific Northwest. I think in places like Alabama or Georgia it remains quite mild in the winter compared to western Oregon and sufficient chilling may not be reliably achieved for best flowering. I would doubt that sufficient chilling would be a problem for bulbs planted directly in the ground in your garden after receipt. The environment in western Oregon is going to provide as much or more chilling that the native environment of the bulb. Anyway, that is what I would do. But, assuming you have a fridge in which you can chill them away from fruits and vegetables, there is no harm in pre-chilling them, either.