Milkweed does not require fertilizers. It actually will bloom much more when grown in poor soils. I've grown many varieties for many years and have never given any fertilizer beyond leaf mulch in the fall. If you do wish to fertilize, I would use composted manure as a top dressing on the soil.

Martha

I tend to amend with compost--I responded to another post of yours recommending native milkweeds. They usually don't need fertilization other than compost and/or amending with leaf mulch as long as they are planted in an appropriate area.

I am wary of chemical fertilizers--think I just read about some study about monarch larvae being affected by chemical fertilizers--will have to go search.

There are other problems with chemical fertilizers--the fertilizers don't attach to soil particles so get washed away and into waterways.

They can harm microbes and other soil organisms (like earthworms) living in the soil--those guys are the ones releasing nutrients for the most part to the plants.

They can create too much green growth thus attracting aphids and other pests who like the tender excessive growth.

There are lots of nice options for organic fertilizers if you still want to do something. Espoma is a good brand, or sometimes you can find fish emulsion. Those are a better choice because they are usually slow-releasing and some of them even come with a little boost of microbes (sort of like probiotics for us).

Attaching a link to Journey North--Monarch conservation site.

Another helpful stop is MonarchWatch.org

Here is a link that might be useful: Journey North