I have one plant and would like collect and plant more seeds.
Here is a link that explains the care and seed collection and propagation.
https://www.gardeningknowhow.com/ornamental/flowers/goats-beard/goats-beard-plant-info.htm
http://courses.washington.edu/esrm412/protocols/ARDI8.pdf
Do I prune goats beard back to the top of the soil in the fall?
I have an Aruncus Goat beard tree. Does it need to be cut down in fall? If so, how much?
You can cut back Aruncus to just above ground level in the fall.
A light mulching of compost to dress the plant is all the plant will need.
https://www.gardeningknowhow.com/ornamental/flowers/goats-beard/goats-beard-plant-info.htm
I have a goats beard in my garden for 4-5 years and it never looked healthy or grew much. Can I add a certain fertilizer to give it more health? I have a sprinkler system every other day for 20 min. Touch water?
Doesn't sound like you're watering "too" terribly much, unless your soil is too clay-like, in which case you'll want to take care of that first. This plant requires "just" the right amount of sun, too. This article may help you:
https://www.gardeningknowhow.com/ornamental/flowers/goats-beard/goats-beard-plant-info.htm
How do I get it to bloom? It is about 10 years old and only bloomed the first year after planting. It has always gotten lots of seedy "plumes" but none have blossomed into any beard resembling anything close to the white feathery plumes of that first year.
They can be picky and definitely prefer to stay moist. Aruncus dioicus ( Goats Beard) is dioecious so it has separate male and female plants. Yours may be the female variety where it has tons of seed plums and is less likely to flower.
I have four Goats Beard plants in four different areas of my yard. They all have flower plumes on them but they have never gotten out of the golden stage that I take as the pre-bloom stage. The plumes are starting to turn brown and have never shown the white plumes that I was expecting. Can you tell me what I may be doing wrong?
I can only tell you from my experience. I moved into a house that already had a goats beard planted. It is on the north side of the house and gets run off from the rain. Basically I do nothing to it but trim away leggy branches every year and it is one of the first trees to bloom in the spring. It seems to like neglect. I hope this helps
What fertilizer should I use?
Alaska fish emulsion is organic and I just started using it last year for everything! It's a wonderful use of something natural and all my plants inside and out love it. Try a week solution at first. You can't go wrong with the stuff. Home depot sells it. Don't order it online. If the container breaks in shipping you sure will smell it.