I assume these are new seedlings sprouted this winter/spring. They need good drainage and little or no fertilzation. Young seedlings can easily die from 'damping off' -- basically the roots rot due to inadequate drainage. I use a standard potting mix such as Promix for winter seeding. Ordinary soil may not be adequately drained, and I don't think sawdust (unless it is very well-composted) is an appropriate soil amendment for potting tender seedlings.

These plants are three months old and perhaps three inches tall. I propogate wildflowers (mostly by division) and put these into my standard wildflower potting mix for sale. I unpotted one today and found a good healthy root system and wonder now if perhaps our recent cold snaps were a bit much for them. They were covered but must have come close to freezing and hopefully will recover now that it has warmed up again. Do you think cold could have yellowed the leaves? The problem certainly isn't a drainage problem as they are in paper pots. I appreciate your comments, however.

I wonder if the plants are suffering from a lack of nutrients in the soil. Sawdust can cause deficit of nutrients in soil as it decomposes. Sawdust contains lots of carbon, but very little nitrogen or other nutrients. As microbes try to use the carbon compounds in sawdust for energy and to build biomass they need to absorb nutrients from the soil to obtain the correct balance between carbon and, for example, nitrogen. This means that nitrogen is being taken from the soil, and your plants may be suffering as a result. The yellowing could also be from a deficit of another nutrient, perhaps iron, caused the same way.

I would try to fertilize the plants with something like Miracle Gro, whih contains both macronutrients (e.g. nitrogen) and some micronutrients (e.g. iron, I think).

One normally wouldn't want to fertilize butterflyweed, especially in a natural setting. This is because the fertilizer would encourage weedy plants. The butterflyweed might grow a little better with more fertilizer, but the weeds would grow a lot better, outpacing the butterflyweed. However, in this case I'd fertilize the butterflyweed seedlings.

I wouldn't recommend sawdust as a soil amendment. I have had problems with sawdust in vegetable gardens, but vegetables need a lot higher nutrient levels than most wildflowers.

My first thought, too, was nutrients but, as I said in my original submission, tried a light fertilizer with no improvement. The sawdust has worked fine for my other wildflowers including some seedlings for 15 years, but something is certainly wrong. I did transplant a few into other soil to see if that made a difference. I'm still betting on cold damage at this point, and have seen a bit of new growth on a few. Thanks for the input, however.

Cold damage usually looks like any of the following: water-soaking like appearence, blackening or browing of tissue, severe wilting and death. Chlorosis or a pale green color usually is the result of nitrogen deficiency or excessive moisture due to bad drainage or compaction. Since it is a mobile nutrient signs begin with the oldest leaves first and eventually throughout entire plant if not corrected. Fe and Mg deficiency would look like inter-veinal chlorosis at first in most plants followed by total chlorisis and necrosis....Look for Fe in younger leaves first and Mg in older leaves first. Mg deficiency also has marginal chlorisis and sometimes Mg deficiency will also have reddish tint to leaf margins and in the cleared vein areas.
If you think your soil is too acidic, try fertilizing your pots with a high NO3 (Nitrate) vs. one high in NH4 (Ammonium) which will help raise the pH rather then lower it....let us know if that helps. I do agree with what Ladyslppr has said... I wouldn't want to fertilize these in the ground.

Vera

In the ongoing saga of my butterfly weed seedlings, I would like to report that all the tops have died back, but all have healthy roots, including obvious caudexs (sp?) (those thickened sections of stem). I have planted them in the ground now and a few are beginning to put up new shoots. Next year I will plant the seeds directly in cells so they don't ever need their roots disturbed.(I need them transportable to sell.) I can't imagine what else could have caused my problems.

I'm a new gardener and I'm a little confused about the below contents and nutrients. I have butterfly weed planted in the ground (mostly clay down here) covered with 2-3 inches of manure (it's been there for more than a year now and I've mixed it into the clay as much as I could manually - fabulous for zinnias). My butterfly weed is yellowing from the bottom leaves, but they're full of blooms. Is this too much water? How do I know if I have a drainage problem? It sounds like I shouldn't fertilize them?

I read recently that butterfly weed likes growing in sandy soil. Lean. I assume we are talking about the orange blooming one here. I have two. The one in the sandy soil is blooming and is almost too times bigger than the one in the richer soil with no sand. Walmart had these last year cheap, real nice healthy gallon sized plants and I picked these both up at the same time. (I'm always surprised to see a native plant at Walmart) I plan to move the littler one next spring to a very sandy spot. Might get yellow leaves if it has had too much moisture? Thats my guess going by the "does best planted in sandy soil" information I read.

Not necessarily, cactusgarden. If you go to Prairie Nursery, you'll find clay busting native forbs. Butterfly weed is one of them. I don't know why butterfly weed sometimes yellows when it's newly planted. After it's established, it doesn't seem to have that problem. I'm going to link you to Prairie Nursery...

To Stephanie, I wouldn't fertilize a native plant, that's me though. They don't get fertilized in nature, so IMO, they shouldn't in our gardens either.

Here is a link that might be useful: Prairie Nursery

Hmm.... I looked it up. They sell plants. I sort of trust that like I do people who sell vitamins touting the benefits.

A lot of sites and sources indicate it prefers well draining sandy loam. The dramatic difference in the two I have is making me lean toward believing it prefers sandy. Both spots have good drainage.

I imagine it will grow in either but for the best looking plant, sandy. The caterpillars end up eating it down to the nub anyway so maybe it doesn't matter. I ended up with two completely defoliated plants last year.

I said they were a nursery! LOL My butterfly weed aren't in sandy or gravely soil and they're doing just great. Yes, Monarch caterpillars will eat the leaves and flowers right off the plants. Last year, mine never bloomed. The cats kept eating the buds off before they ever bloomed! I did plant the butterfly weed for them though, so that was fine with me that they didn't bloom. Everything I find for swamp milkweed tells me it needs wet soil. At the very least it needs consistently moist soil. I don't have that. I have dry soil. Really dry soil. Unless it rains of course, then it's wet, otherwise dry as a bone. However, my swamp milkweed grows and thrives! Hmmm...

I think maybe we are talking about two different plants terryr, in which case I say "never mind"? :-x

I just looked up "Swamp Milkweed" and its pink. I am talking about the orange one, Asclepias tuberosa which is a native to dry fields.

Another one I have is Asclepsias asperula 'Antelope Horns'. I have it planted in the median between the sidewalk and the street in pure sand, with no amendments, in the hottest, most inhospitable spot (reserved for plants demanding torture which grow in inhospitable spots in the wild like out of rock crevices) and it is big and happy there.

There is a desert variety, Ascelepsias sublata, I would love to grow but I am in a zone too cold for it. It looks kind of like a euphorbia, is blue and gets 3 to 4 feet high. It is so cool looking! :-o and a real WOW kind of plant!

Sorry it took so long to get back to this, cactusgarden!

No, we aren't talking about 2 different plants. We're talking about Asclepias tuberosa. The orange one. :-) It's still a never mind, or who cares...lol...

I keep reading about people planting some tropical kind, used as an annual. Would the Asclepias sublata work in the same way I wonder?