I have not found that statement to be true. I have hundreds of bulbs in various size pots which are grown outside in part shade year round. I insanely repot almost all of them each year to check on their roots. Rootbound bulbs will usually show a dying off of roots in the most central part of the rootball. If they are not removed before active growing I will usually find disease spread to the basal plate which can result in the bulb dying (think mush).

This does not mean that all bulbs need to be potted up. Some of my bulbs are small (DNA) and are in gallon pots, some larger bulbs are in 3 gallon pots. Some send down long roots so need a deeper pot and some have a more shallow root system. This is especially important to know when growing species.

In reponse to water requirements, since I grow in the subtropics, we have a natural dry season that slows growth. I do not water during this time. Some keep their leaves, some die back. I have found that the ones that die back have the most dead roots that need to be removed when repotting. I think if they were growing in the ground that the dead roots would be composted, but in pots they just encourage disease.

I hope my experience will help you in some way.

Jody

The only thing I can think of is that in nature, some hippies tend root in pockets of organic material either in the ground, among rocks or in the crook of trees. It could be that someone in the distant past thought that this is the best way to grow them but since then so many hybrids have been made from so many geographical locations that growing them this way is irrelevant at least with the more modern hybrids.

I totally agree with Jody and I repot mine quite often and inspect the roots/bulb for any rot during that process. One thing I do is try not to fuss with healthy roots and just pot them up into a larger container (unless I'm separating the offsets) and add fresh medium on the bottom and around the root ball. This is my five cents worth and I grow mine in pots exclusively cuz I'm in the cooler growing Northeast so I really don't have a choice.

Jody and Fred,

Thank you both very much, this is good information. I feel freer to use larger pots now. I don't know if I'll repot again this year (I'm short of soil anyway and it's hard to find in larger quantities at this time of year), but if I do I will evaluate non-standard options.

Jody, I'm not sure what kinds of bulbs I have, as far as whether they like to send a lot of roots deep or not. (They're all modern hybrids though.) I've just gone with the conventional wisdom. But with some plants, this has led to roots practically climbing out of the pot, looking for something more to grow into, poor things. I think when I see that I will up-pot and give them what they seem to want.

Joan