Acorus, commonly known as Sweet Flag, are very easy to grow when planted right and in the right spot. Some varieties tolerate a drier soil while others like a consistently moist or boggy soil. Most like part shade however some will tolerate full to mostly sun. Therefore, in design and before planting, it's a good idea to know the sun and moisture needs of the specific varieties you intend on growing. You'll find these specific light and moisture needs on any and every plant page in the Wilson Bros Gardens website. 

Here's a breakdown of what you need to know regarding planting and caring for Acorus sweet flag plants...


Soil

As mentioned above, some Acorus varieties prefer a consistently moist to boggy soil while others like a drier, well-drained soil. You'll find these specific light and moisture needs on this any Acorus in this site. 


Soil pH

Soil pH is a measurement of the alkalinity or acidity of soil, which is measured on a scale of 1-14, with 7 as the neutral mark. Any measurement below 7 indicates acid soil conditions, and anything above 7 indicates alkaline.

Acorus grow in soils ranging from 5.5 to 6.5 on the pH scale. Most average garden soils fall between a pH range of 6.0 to 7.0. 

If you're unsure about the pH of your soil, or whether or not it's suitable for growing Acorus, it's a good idea to test the soil pH in the planting area. You can quickly test soil pH with an inexpensive soil pH tester probe. To raise the pH (make more alkaline) you can add pelletized limestone to the soil. To lower the pH (make more acid) you can apply Soil SulfurAluminum Sulfate, or Chelated Iron. Adding organic compost to the soil or using compost as mulch can also help to increase acidity and maintain acid soil conditions.

NOTE: Under the description tab on every plant page in Wilson Bros Gardens you'll find the soil pH range the plant will perform best in. 



Light Needs

Most Acorus prefer a shady to partially shaded site however some will tolerate more sun. Therefore, in design and before planting, it's a good idea to know the sun and moisture needs of the specific Acorus variety you intend on growing.




Planting Acorus In Garden Beds

(Scroll down for advice on planting Acorus in containers and pots)


Step 1

If you are not tilling the soil in the entire planting area, start by digging your planting hole at least two to three times as wide and only as deep as the height of the rootball of your plant. Place native soil removed from planting hole around the perimeter of the hole, in a wheel barrow, or on a tarp. When planting in tilled soil just dig the planting hole the same size or a little larger than the rootball of the plant.


Step 2

Depending on the type of Acorus you are planting and the level of soil moisture, you might need to amend the native soil. When planting in dense clay or poor soil it is often beneficial to thoroughly mix in some good organic matter, such as composted manure, homemade compost, sand, bagged top soil, and/or a good planting mix at a 50/50 ratio with the clay soil.


Step 3

To remove your Acorus plant from the container it was growing in, squeeze the container with your hands to loosen the rootball and then try to very gently lift and remove it from its container. Be careful not to damage your plant when removing it from its container. If the rootball is stuck in the container use some snips to cut the container away. After having removed the plant from the container, use your finger tips to gently loosen some feeder roots around the surface of the rootball. 


Step 4

Set your plant in the planting hole so that the top edge of the rootball is at or slightly above ground level. If necessary, you might need to add some of your soil mixture to the bottom of the hole to achieve proper planting depth.






Step 5

After setting your Acorus plant in the planting hole, use one hand to hold the plant straight and your other hand to begin back-filling your soil mixture around the root ball, tamping as you go to remove air pockets. When you have filled the hole to the halfway point you can soak the soil. Then continue back-filling to the top edge of the rootball.


Step 6 

Next, deeply water the planting area, including the root ball, to a depth equal to the height of the root ball. 


Step 7

Spread a 1-inch layer of shredded or chipped wood mulch or pine straw around the planting area to conserve moisture and to suppress weed growth. As the mulch decomposes it will add vital nutrients to the soil that your plants will appreciate. Avoid using freshly chipped or shredded wood for mulch until it has cured in a pile for at least 6 months, a year is better. Also avoid placing or piling mulch directly against the base of your plant as this could cause the stems to rot.




Planting Acorus in a Container


Acorus add a grassy texture and nice color to container gardens. Plant them alone in a pot or mix them with other plants that have similar soil moisture and sun needs. Some varieties appreciate a drier soil while others like a consistently moist or boggy soil. Most like part shade however some will tolerate full to mostly sun. Therefore, in design and before planting, it's a good idea to know the sun and moisture needs of the specific Acorus varieties you intend on growing. You'll find these specific light and moisture needs on any and every plant page in the Wilson Bros Gardens website. 

When growing in pots, I suggest using a premium quality potting mix and a container that has drainage holes. If the variety of Acorus you are planting likes a lot of moisture in the soil, you can substitute the potting mix with a potting soil.  

Make sure to choose a container that is large enough to allow for 2 to 3 years of growth before shifting up to a larger size container. This might mean your planting pot would be 4 inches or more in width than the root ball of your plant. If you will be planting other plants in the same container with your Acorus up the size of the container.

Container color will matter as well. Not only will you want to pick a color of container that goes well with the foliage color of your Acorus, you'll also want to pick a container that matches the style of your home or other structures and other plants in the surrounding environment. 

Many nursery & garden centers offer a wide variety of containers to choose from. Before heading out to buy a container take pictures of your home and the surrounding environment. Doing so will help you to choose just the right color and style.


Container Planting Instructions


Step 1

Before filling your container with the soil mix, we recommend lining the bottom with shade cloth or a porous landscape fabric. This will keep the drainage holes from becoming stopped up with soil. Using gravel in the bottom of the container doesn't work well as roots will grow through the gravel and clog the drainage holes.


Step 2

To remove your Acorus plant from the container it was growing in, squeeze the container with your hands to loosen the rootball and then try to very gently lift and remove it from its container. Be careful not to damage your plant when removing it from its container. If the rootball is stuck in the container use some snips to cut the container away. After having removed the plant from the container, use your finger tips to gently loosen some feeder roots around the surface of the rootball.  


Step 3

Pour a small amount of your soil mixture in the bottom of the container. Set the rootball of your plant in the container and make necessary adjustments by adding or removing some soil so that the top edge of the root ball will sit 1/2" to 1" below the rim of the container.




Step 4

Backfill with your potting soil around root ball, tamping as you go, until the level of potting soil is even with the top edge of root ball.


Step 5

Water thoroughly until water starts to drain from the holes in the bottom of the container. Add more potting mix if settling occurs during watering.


Step 6 (Optional)

Apply a 1/2" layer of bark chips or sphagnum moss to soil surface to help conserve moisture. 



Feeding Acorus Sweet Flag


Acorus plants are light feeders that require little if any fertilizer. Unlike lawn grasses that need regular applications of high-nitrogen fertilizer, Acorus would prefer an annual feeding in late spring or early winter with a natural or organic plant food. Alternatively, a slow-release low-nitrogen fertilizer can be used.



Watering Acorus Plants


At planting time, deep soak the soil around the rootball, including the rootball, to a depth equal to the height of the rootball. Thereafter, depending on the needs of the moisture needs of a specific Acorus variety, water as needed based on weather conditions. Keep in mind that the soil in containers and pots will dry out quicker than ground soil. Check soil moisture frequently by touching the soil with your finger tips. Eventually you'll come to know when your plants could use some water.  



Pruning Acorus Plants


Most Acorus are evergreen throughout most of their growing range and will require little if any pruning. Where not evergreen, foliage should be cut to the ground and removed in late winter before new growth begins to emerge. Even in regions where Acorus are evergreen, after an unusually cold winter that damages or discolors foliage, plants should be cleaned up, cut back or mowed by two-thirds their height. 



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