I am including images of a couple of my plants. They all look similar.
Astilbe is a shade plant. If yours is getting afternoon sun, it may be leaf scorch that you see. Astilbe chinensis tolerates sun and dry spells better than Astilbe arendsii. However, even the A. chinensis varieties need consistently moist soil if they are in sun. If your plants are new, they may not be to blooming size yet; your plants look small but they might be a dwarf variety. Blooming takes a lot out of a plant and one that is under heat, nutrient deficiency, drought or other environmental stress may forgo blooming.
Here is an article on reasons for non-blooming astilbe: https://www.gardeningknowhow.com/ornamental/flowers/astilbe/astilbe-not-blooming.htm. The following link goes to general astilbe care: https://www.gardeningknowhow.com/ornamental/flowers/astilbe/growing-astilbe-plants.htm
astilbe flowers have turned brown.
They may have just completed their natural cycle, but there could be other reasons. https://www.gardeningknowhow.com/ornamental/flowers/astilbe/growing-astilbe-plants.htm
Will they survive the winter?
Yes. they are very winter hardy, but you need to keep them watered till established.
https://www.gardeningknowhow.com/ornamental/flowers/astilbe/astilbe-winter-care.htm
https://www.gardeningknowhow.com/ornamental/flowers/astilbe/growing-astilbe-plants.htm
Hello and help! When we had our backyard professionally landscaped a couple of years ago, they planted three what they told me were "astilbe" plants. The plants took root wonderfully but now are so tall and wide they're just taking over. I was wondering about when and how I could trim them back. I looked online for information about astilbes but all I found were smaller flowering plants. I'm totally clueless about this so would appreciate any help you can give me! I don't want to accidentally kill the beauties! I'll attach pictures of the plants from now and when they first were put in.
There are different varieties of astilbe, with different heights.
https://www.gardeningknowhow.com/ornamental/flowers/astilbe/types-of-astilbe.htm
The best time to prune is after the flowering cycle. Do a light to moderate height reduction by selective shaping. Don't take more than 25% of the foliage at one time.
https://www.gardeningknowhow.com/ornamental/flowers/astilbe/growing-astilbe-plants.htm
I ordered astilbes bulbs The included planting guide says to plant ASAP. It also says not to plant until the average temp is 60 and the low temp 40. The problem is the high temp has not gotten higher than 49 and the low is not expected to be above freezing for at least a week.what should I do? Thank you, Debbie Bittner
You can plant them in a pot big enough to accommodate them with potting soil and let them get started indoors. Then after all danger of frost has passed, you can transfer them outdoors.
https://www.gardeningknowhow.com/ornamental/flowers/astilbe/growing-astilbe-plants.htm
But after about a month the ruby red has no color brown it is in a pot and I keep it moist in mainly shade maybe 2 hrs of sun per day. Is this normal? answer to mrozinski50@att.net
Unfortunately, your photo did not come through. I am unable to see the issue at hand.
It does sound like an infection, and from the description of soils that don't get a chance to dry out, this will be even more likely.
A fungicide may be in order, as well as correcting watering habits. Make sure that the soil has a chance to dry only down to about half an inch between waterings. Any more or less will pose problems. Saturated soils will be bad, but so will dry soils.
Here are some articles that will help:
https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm
https://www.gardeningknowhow.com/ornamental/flowers/astilbe/growing-astilbe-plants.htm
I know they're perennials, but mine aren't doing well even in spring. Do I need to replace them?
Their vigor will depend, very heavily, on their environment. They tend to be a little picky.
The plant requires shade, and only light dappled sun. Too much sun will scorch them.
They should not be allowed to dry out, fully. They are not tolerant of dry soils.
Here is an article for more information on keeping these plants happy and healthy:
https://www.gardeningknowhow.com/ornamental/flowers/astilbe/growing-astilbe-plants.htm