Goodness gracious me, what a spate of reactions!
First off my thanks to those of you that have written both publicly and privately with tips, tricks, and ideas about how I might grow potted things better. I appreciate your willingness to help.
Please allow me to explain where I’m coming from. I am a small scale COMMERCIAL grower. The observations that I make and my growing orientation is from a commercial growers viewpoint. As a general rule, I DO NOT grow daffodils in pots in my greenhouses that are for resale. Most things are grown in pots here to manipulate bloom time. Sometimes for pollen, sometimes for seed set, and sometimes (hopefully) for both. There is around four hundred square feet of bench space dedicated to pots of daffodils. Most are in 4 1/4 inch talls (fit 16 of these to a 17″ x 17″ nursery flat) although I use some plastic quarts (6″ x 6″) and some clay long toms for a few finicky species. Yes, some long toms are double potted which is a classic rock gardener strategy.
There are always tradeoffs. Physical greenhouse space, time (as in: there are only so many hours in a day or eight day weeks and 29 hour days would be ideal), costs (soil, fertilizer etc.). Almost everything is repotted annually with some things once every two years. I do pay to have extensive soil testing both outdoor and indoor. My soil mix hasn’t really varied in the past fifteen years being ProGro #5F which is a consistent nursery standard here in the Pacific Northwest (1/3 peat moss, 1/3 pumice, and 1/3 composted bark dust) which I amend with 8% perlite and I do add specified trace elements. As an example, I do find it very difficult to translate “1 1/2 pounds of magnesium sulfate per acre” to calculate and apply an even application of grams per cubic yard in my potting mix. Ph is maintained at 6.5. Fertilizer (NPK) is added as specified by soil tests for my crop. I try very hard to eliminate inconsistencies in my growing.
Even with all of the above, I am not able to get either the weight or size of bulbs grown in pots versus those grown out in field rows. I find at least a 10% differential with an average of possibly as much as 15%. Again, as a commercial grower I am interested in producing the largest and finest “product” that I can muster. This difference is why I state that I can’t grow as well in pots. Possibly this difference is so slight that it might not even be observed by many growers.
Having said all of the above, if I were in a situation that allowed no use of acreage, I wouldn’t hesitate in the least to grow in pots.
Steve