I don't know the for sure answer, but Blue Horizon is a F1 hybrid. Therefore, seeds harvested would not be true. However, one lady told me that she harvests her tall blue ageratum seed each year, that was originally from Blue Horizon, and still gets nice tall, blue flowering plants. ?? I think it's fun to just try and see what you get. I tried collecting seeds autumn 2001 but must not have had any seed amongst the chaff as I had no germination at all.

I have let blue Horizon self seed in my garden for two years, and the seed produces consistently tall BH type plants.

gail

Hi, Everyone,

I went to the Ageratum forum to see what anyone has to say about the "tall" variety. Several years ago I purchased a markrt-pack of ageratum from my local roadside produce stand. I was not expecting anything but just the regular Ageratums, but these grew a good 12"-14" tall.
In most of the following years, new seedlings came up in the bed, evn though I dug in it and "disturbed" it. I SO appreciated this taller variety, that I started moving them around while they were still small.
Last year, I took the tops off, with the spent flowers on them (gone to seed), and rubbed them over a couple of other beds. This year, 2003, I have quite a crop of them! They are now transplanted in several beds and just starting to be in full bloom. One of these plants can almost cover a square foot area by the end of summer! They are good "fillers in" for late summer bloom when there are "holes" in your beds left by bulb foliage that (finally!) died.

I will try to, actually, gather some seed this year. The seed is SOOOO smalL!!!! Like specks of dust! I think it has to be "dropped" in the beds in late summer so it can go through the normal cycle of dormancy and sprouting next Spring. (By the way, this Ageratum does not germinate until early July or so here in MD).
I will try to gather some seed, and if I am successful, do not mind sharing it with you all. Don't know just how much I will get. I only have about 15 plants in my garden now.
I DID read somewhere recantly that seeds to the tall variety are now hard to come by.
By the way, they look the same each year, so they DO seed "true" in my opinion.
Gitagal

I have been growing and regrowing "tall ageratum" for years. I gather the seeds and start indoors, and have used seeds years old. They may not be "true", but the sure look tall and blue/lav... if anything, they seem to be getting taller .. 2 ft.

Folks!!!!! I'm not sure if what I have is "Blue Horizon" but I sure wish that you all could take a bit of it off my hands. The one that I have grows 15-18 inches tall and blooms here early Sept. It spreads rapidly, however, it is easy to pull out. I have what I will refer to as a very large patch of it over in one of my island beds. The color is such a pretty blue/pur that I feel it is worth some of the trouble. I need to pull it out NOW and get some of it into pots to keep it in better control.