How to Plant, Grow and Care For Astilbe
Thinking of growing some Astilbe in your garden this season? This shade garden favorite has beautiful blooms in many different colors. In this article, certified master gardener Laura Elsner takes you through every aspect of growing astilbes in your garden, including maintenance and care.
Astilbe is an herbaceous perennial that you should consider adding to your garden. It brightens up shady areas with large plumes of feathery flowers. Astilbe is a tidy perennial flower that doesn’t spread. Its blooms last a long time, and its foliage has a lovely lacy texture.
Astilbe blooms in many different colors. Their beautiful flowers can be seen most commonly blossoming in white, pink, red, and purple.
If grown in its ideal conditions, astilbe has few problems with pests and disease. Astilbe can also handle a wide variety of growing conditions making them easy and versatile. Keep reading to learn all about growing astilbes this season!
Astilbe Plant Overview
Plant Type Herbaceous perennial
Native area Eastern Asia, North America
Hardiness Zone 3-8
Exposure Part-shade to part-sun
Plant Spacing 18′
Planting Depth to the crown of the plant
Watering requirements Moderate
Pests Black vine weevil
Diseases Powdery mildew
Soil Type Rich, hummus
Flower Color Pink, red, purple, white
Plant with Hosta, ligularia, hydrangea, creeping Jenny, coral bells
Astilbes are native to Japan and China. There is a variety that is native to North America. The North American variety is also known as the false goat’s beard.
This variety is tall with white flowers. But the large, blossomed astilbe that we see as a garden ornamental is mostly the Japanese (Japonica) and Chinese (Chinensis) species. These ornamental varieties were distributed across the globe in the late 19th century.
German horticulturist Georg Arends started to cross-breed and create hybrid varieties, which are still around today and are called astilbe x arendsii.
Astilbes are a member of the saxifragaceae family. Other members of this family include coral bells, bergenia, and rodgersia.
There are eighteen species of astilbe and many cultivars. Two common species that gardeners will encounter are Japonica and Chinesis. Chinensis astilbe is the later blooming variety, whereas Japonica bloom in the early summer.
Other species include thunbergii and simplicifolia. Thunbergii has plumes of flower drape slightly downwards. Simplicifolia is a dwarf species of astilbe, which is great for small spaces and front borders.
There are a variety of ways to obtain an astilbe plant for your garden, let’s run through them.
Purchasing an established plant is the easiest way to get astilbes into your garden. They are a very popular garden perennial, and you should have no problems finding one at your local garden center or nursery.
When choosing an astilbe, read the tag carefully for bloom time. Some bloom early in the summer, and others bloom in late summer. In general, Japonica will bloom early, and Chinensis will bloom later in the season.
Bare roots of astilbe can be purchased from seed catalogs and online. Make sure you choose a reputable company to purchase from. This is a great option if you are looking for a specific variety.
You will receive a dampened root in the mail. Sometimes packed in peat or wood shavings. Keep the root damp. Open your package and soak it in water immediately. Plant it as soon as possible.
To plant your root, dig a hole 2-3 times as wide as the size of the bare root. Gently tease the roots apart, so they aren’t growing in a circle. Fill with a mix of the existing soil and some organic material. Make sure you water well.
Keep a close eye on your new transplant and make sure it doesn’t dry out. This is best done in the spring or fall. Planting in the heat of the summer is risky because your astilbe can dry out quickly.
Dividing existing plants is a great way to get more astilbes. They won’t need to be divided too often. But they will eventually grow large, perhaps too large for their space, and require division.
Another sign they need to be divided is that they are flowering less because of overcrowding. This could be once every 3-4 years or so. Maybe more in cold climates where they tend to grow slower.
Division of astilbe is best done in the fall. For the early blooming varieties, you could do this in the late summer. Make sure it’s after they have finished blooming. It’s best to pick a cloudy, cool day to divide, transplant and plant.
Dig up your astilbe. If the soil is hard, water it first to make digging easier. I use a sharpened edger or my spade to split the astilbe into chunks. Depending on the size of your astilbe you can split it into 1-4 chunks. Replant the original piece back into your garden. Water in well. It will need more water until the roots can re-establish.
Dig holes for the new transplants. This is actually better to do before you dig up the plant. Dig the hole extra wide and deep. Plant the transplant and fill in with a mixture of the soil that you dug and some organic matter. Water in well.
Do not let the new transplants or the original plant dry out. Water is key for transplant success. Your new transplant and the original plant may sulk and not look the best but keep watering it and it will grow fresh next spring.
Planting an astilbe is a fairly straightforward process. If you are familiar with planting perennials in your garden, astilbe will be a cinch.
Start by digging a large hole. Dig it three times as large as the plant itself. This will allow for the roots to easily spread and establish. I will then fill the hole with water. Allow the water to sink in. At this point, I will add a handful of transplant fertilizer, or you can add some bone meal or blood meal.
Then remove your astilbe from its pot. If the roots stay in the shape of the pot, you will have to break up the root ball. You can do this with your hands, or if it’s really dense, use clippers. If the bottom is a big mat of roots, I will take a knife and slice it off.
The plant will struggle if it is planted with roots that are wrapped around it. I try to avoid purchasing overly root-bound plants in the first place. But sometimes it’s unavoidable (I can’t resist a sale!).
Next, place your astilbe into your pre-dug hole and line up the crown of the plant with the soil line. Then fill in the hole with a mixture of existing soil and some organic material. Now water it in and press the soil down, so it is firmly planted.
Water it well to help establish its roots. If possible, pick a cloudy and/or cool day to plant your astilbe. Or plant it in the morning or evening to avoid the heat of the day. This will limit the stress on your new transplant.
How to Grow
Astilbes grow in a variety of conditions. You will just have to pay attention to the amount of water they get with the amount of sun they receive.
Let’s look closer at the ideal growing conditions for astilbes.
Astilbes can handle a wide variety of sun conditions. While they are generally touted as shade perennials, I think part-sun is the sweet spot for growing astilbe.
In a full shade area of your garden, your astilbe will be mostly a foliage plant. It will have lacy leaves and very few if any, plumes of brightly colored flowers. In warmer zones, you will want to plant your astilbes in shadier areas to protect them from the hot summers.
In a partially shaded or dappled sun area, your astilbes should flourish. The morning sun with dappled afternoon shade is a perfect location. Here you will get big fluffy plumes of flowers.
Astilbes can be grown in full sun. Just be aware that their flowers will fade out faster. Also, you will need to be watering them more frequently. This works for colder climate gardeners; the summer sun might get too hot for them in warmer garden zones.
Astilbe prefers rich, well-drained soil. They like a slightly acidic pH. This can be achieved by adding organic matter such as compost, aged manure, worm castings, or sea soil to your garden before planting. This will also help loosen clay soil and help with drainage.
For very alkaline, clay soils, try an ending with coconut coir or peat moss to loosen your soil. You can tell if your soil has a lot of clay by simply grabbing a handful of it and squeezing it.
It should crumble away back to soil once you release it. If it stays in a tight ball, it has a high clay content. Clay is alkaline and should be amended with coconut coir or peat moss and organic matter to lower the pH for astilbes.
This is what most of the typical shade-loving perennials prefer as well (e.g. Hosta, hydrangea, etc.). So, if you already have an established garden, it should not be a problem adding in some astilbes.
Watering is the tricky part for growing astilbes. While they require more water than typical perennials, they do not like being left in standing water. You have to find the sweet spot where they receive adequate but not too much water.
Make sure your soil has adequate drainage. This means that it doesn’t not have sitting water. Boggy areas in your garden are not suitable for astilbe even though they are known as water-loving plants. Add coconut coir or peat moss and plenty of organic matter to help with drainage.
Astilbes do not like to dry out. Make sure the soil is evenly moist. The tips of your article will go crisp if they are drying out. They also like to be continuously moist. Try not to let them dry out completely at any point.
If you are planning your astilbe in full sun, you will need to be providing more water as they will dry out faster. I like to use a drip hose snaked through the garden and give them a slow feel watering once or twice a week as needed.
Climate and Temperature
Astilbe has a great range for differing climates. They can survive anywhere from zone 3 to zone 8 with no problems.
As for temperatures, you will want to keep your astilbe protected from harsh heat and sun. Planting your astilbes in an area that receives afternoon shade will keep them flourishing.
I am not an advocate for applying fertilizers to perennial gardens. Instead, I believe in soil health. Soil is a living thing full of microbes that is essential for soil structure. In the long run, healthy soil will make healthy plants.
Every second-third fall season, I add organic material to my garden. I also top-dress the garden with compost, aged manure, sea soil, or worm castings. I then apply a compost tea (usually made from worm casting) at some point in the season. This keeps my soil healthy and, therefore, my plants healthy.
Astilbes are a wonderfully low-maintenance perennial (unless you planted then in an area where they require extra water). They do not need to be deadheaded.
They will not produce a second flush of flowers if you deadhead them. Plus, I think the dried plumes of flowers after they finished blooming still add interest and texture to your garden.
They do not need to be cut down in winter either. The dried stalks can stay on through the winter. In the spring, you can give them a quick trim to the ground and allow them to grow fresh again.
There is a secret for longer-lasting astilbe blossoms, and it’s not what you might think. It’s not watering, pruning, or location. It is all in the different astilbe varieties. There are two different types of astilbes that bloom at two very different times in the season.
If you stagger plant early blooming varieties with later blooming varieties, you will have astilbes in bloom almost all summer long. For a more comprehensive list of astilbe varieties, check out my article on 19 varieties of astilbe. Below are a few of my favorites.
‘Fanal’ flowers are plumes of feathery scarlet red flowers. It blooms in the early summer. If you mix this variety with another red variety, such as ‘Burgundy Red’, you will have an almost seamless blossoming of red astilbes through the summer.
‘Younique Salmon’ is an early summer blooming variety. It features large plumes of peachy feathery flowers. It looks like a coral reef in the garden.
‘Sprite’ is a dwarf variety of astilbe. If you are short on space or want a front border plant, ‘Sprite’ is a great little variety. It features light pink flowers on fine jagged foliage.
‘Ostrich Plume’ is a unique variety of astilbe. It has bright pink flowers that dangle downwards. It has the look of loves-lies-bleeding. These little dangling plumes grow on top of glossy lacy foliage.
Astilbes make great companions to a variety of perennials in your garden. What makes great companions are plants that like the same growing conditions. Here are a few of my favorites, but there are many more perennials to combine with astilbes.
Astilbe and hostas are a match made in heaven. They both like part-shade and lots of water (but not standing water). The wide round hosta leaf is the perfect contrast to the lacy-textured astilbe leaf.
Then the plumes of astilbe flowers will rise slightly above the hosta. You can plant astilbe behind hostas, or you can stagger them in between.
Ligularia is a large water-loving shade perennial. They go great with astilbe. The later blooming varieties of astilbe will bloom at the same time as ligularia.
The early blooming ones will bloom before. I would stagger a mixture of early and late blooming varieties around the base of your ligularia for flowers throughout the summer.
Coral Bells are known for their stunning foliage colors. They also have beautiful, ruffled leaves. They make a great contrast with the fine foliage of astilbe.
Coral bells shoot up long stems of foamy flowers. They look great when interspersed with the thick plumes of astilbe flowers. It looks lush and whimsical.
Bleeding hearts are one of the first perennials up and out of the ground in the early spring. They grow large and lush and then die back in the late summer.
Plant astilbe around the base of the bleeding heart so it will cover the hole left behind. Late blooming astilbe will bloom and cover the hole left by the bleeding heart.
Creeping Jenny is a low-growing ground cover plant. It can be quite aggressive. Why I like this plant with astilbe is that it acts as a natural mulch. It will keep the moisture in the soil. You may have to rip out some of the Jenny as if it starts to grow into the astilbe.
The golden variety of creeping Jenny looks great paired with a red variety such as ‘Red Sentinel’. The dark burgundy stems really pop against the chartreuse foliage of the golden creeping Jenny.
Pests and Diseases
One of the best things about astilbes is that they remain relatively disease and pest free. Especially if they are grown in their ideal conditions as outlined above. There are a few issues that can affect astilbes, but it isn’t too common.
I think if anything is going to affect your astilbe, it will be powdery mildew. Unfortunately, what powdery mildew and astilbe have in common is that they both like shady and wet conditions. Powdery mildew appears as a powdery white, dust-like film that can be wiped off.
It is best to try and prevent powdery mildew from forming in the first place. Keep your astilbe growing in its ideal conditions (check out the how to grow section above). Make sure to plant your astilbe 18-24″ apart. Allowing adequate airflow between your plants will prevent powdery mildew.
Also, avoid overhead watering. Constantly wet foliage is a breeding ground for mildew. I like to use a drip hose snaked through the garden. This provides water right at the soil level.
If you do have an overhead watering system, water in the morning. This way, the foliage will dry in the sun. Watering at night, the plant will sit wet through the night. This promotes powdery mildew growth.
If you already have powdery mildew in your plants, tips about prevention aren’t going to help. You will need to purchase a fungicide and spray the affected plants.
Use one specifically formulated to combat powdery mildew (it will say in the bottle). In the fall, clean up all the leaf litter and dispose of it. This is to help prevent recontamination the following season.
Black Vine Weevil
Weevils are a terrible pest to deal with, unfortunately. Black vine weevils are small bugs with round bodies that have a pebbled texture.
These bugs feed on the roots of your astilbe and will eventually cause your astilbe to fall and die. The problem is these little bugs are hard to see and usually only come out at night.
If you any symptoms of weevil, or see the bugs themselves, try introducing beneficial nematodes to combat them. If this doesn’t work, you will have to apply a pesticide.
It will take a few applications to be effective. Black vine weevil will over winter in the soil, so make sure to deal with it so you aren’t plagued with them season after season.
Frequently Asked Questions
How do you prepare astilbes for winter?
You don’t have to do anything really special for astilbe to prepare them for the winter. You can cut them back in the fall if you like. Or you can leave the dry flower stalks on through the winter. Whatever you decide, make sure you are watering your plants in well until they go dormant. Do not let your astilbes dry out.
What are the best growing conditions for astilbes?
Astilbes grow best in evenly moist soil conditions. They are mostly thought of as shade plants. But if they are receiving more water, they can take more sun. In warmer climates make sure they are protected from the hot afternoon sun.
How do you keep astilbes growing all summer?
Water. Make sure they have lots of water, without being left in standing water. The best way to achieve this is by having well-drained soil. Amending your soil with its of organic material will help make it drain. If your soil is very heavy (clay), you may need to dig in some peat moss or coconut coir to loosen it.
Can astilbes be overwatered?
Yes! While astilbes are often touted as water loving perennials, they actually do not tolerate being left in standing water. Make sure to keep your astilbes evenly moist, but never waterlogged. Achieve this by amending your soil with lots of organic material. For very heavy clay soil, dig in coconut coir or peat moss to loosen it and help with drainage.
How much sun do astilbes need?
Astilbes do need some sunlight in order to bloom. Morning sun is great with some protection from the hot afternoon sun. The more sun your astilbes get, the more water they will require.
Astilbes are a garden mainstay. They are a low-maintenance tidy perennial that blooms year after year. As long as you keep them watered, but not waterlogged, they will give you very few problems. So, pick up a few astilbes and add them to the shady areas of your garden. Their big plumes of feathery flowers will add drama and color into your garden.