It is all in the growing conditions, including climate and weather, moisture, fertilizer, soil, and the cultivar itself. Some southern-bred daylilies sit and sulk in my zone 6a garden, and others seem to love the conditions in my garden. What zone are you? I would love it if all that follow this discussion group would include their climate zone.

Care to name the cultivars you are writing about?

Every daylily will spread over time, but each variety is different. Some spread faster than others. The conditions in which the plant is growing are a factor also; two plants (however you define a plant) in the same garden may preform differently. Having said that, the general rule is that daylilies should be divided every three to four years.

I bought eight "plants" in 2011 (more than one fan in one pot). Of those eight, four were divided last year, and that was the the first time I ever divided plants.

I have some orange "ditch lilies", no hybrid or anything but it is pretty looking. I was just curious on how it will grow out. I know they are suppose to be quick growers but I see post about "clumps" and didn't know if that was only a certain type of daylily that clumps or not.

A "clump" is in the eye of the beholder. The only real definition I know of is the "fan", which is the smallest division a daylily can have. It's one group of leaves that form - guess what - a "fan". Intuitively, a "clump" would be a group of several fans growing close together. I know of no daylily that can be said to "clump" better than any other. Some just spread faster than others.

Daylilies will propagate themselves by growing new fans from their roots. Other than a thing called a "proliferation", that is the only way a daylily can produce an identical copy of itself. Over time, a single fan will produce a "clump" but as I indicated earlier, spreading of daylilies takes time - filling a 10' by 10' space from one fan would take many years.

BEWARE OF THE DITCH LILY! Keep them away from ANYTHING ELSE you value in your garden. They have voracious roots that will that will strangle out anything in their path.

how far away are you suggesting? I just have them on the side of a bed with grass on one side and some hydrangeas and other plants 6-8ft away on the other. if they start spreading can I just dig them up ? i do want them to fill out but is there any way i can build a box, like dig in some wood far enough in the ground to keep them from spreading out.

Bsmith , just to give you an idea of What ditch lilies can do ......I grow them here because I use the petals to make wine . but even here mine are at the point that I will have to go in and hack and slash . Taking over in some of the spots I had planted them . Some are just fine where they are and I use some to edge the garden rooms
, yes you can dig up but dont leave any roots or they will be back . Might take a year or even 2 but those little bits of thick fiberous root will sent up shoots when You least expect it .Once established , they can increase a couple of feet per year

I would like to know what others think about building an underground wall to keep them contained. Does anyone on this forum have experience with such a thing?

You could also try "pruning" the roots by pushing a spade into the ground all the way around the perimeter of the clump. A typical spade is about a foot long and you would have to push it in to the hilt, and have plenty of overlap so as to avoid leaving gaps that the roots might sneak through. I'm not sure if a foot would be deep enough - perhaps someone else can answer that question also.