Beware of the Rose of Sharon (Althea) in your garden

Rose of Sharon, Hibiscus syriacus, AltheaThe Rose of Sharon (Hibiscus syriacus) also known as an Althea shrub is a mid summer bloomer in white, pink, red, or purple with a red center. You can also find them ruffled in the same array of colors including what many call blue. You can grow the Rose of Sharon as a shrub or a tree and many garden catalogs sell them as a fast growing deciduous flowering hedge.Rose of Sharon, Althea shrub, Hibiscus syriacus

The Rose of Sharon grows in zones 5-9 (but I have seen a listing for up to zone 11) and can be quite a prolific re-seeder. In my zone (7) it can be invasive and pop up where the seeds may fall or the wind takes them. Many sites will tell you that the height can reach up to 10′ tall and 6′ wide but I can confirm that I have a ruffled purple one that is 8 years old and is well over 12′ tall and 6′ wide. It has never had viable seeds yet and last summer transplanted a purple one to the same area of the yard to see if that will make a difference (sometimes plants need another for cross pollination). It grows in most soils and will tolerate the hot summer sun. Rose of Sharon bush, Althea, Hibiscus syriacus

About 3 years ago I discovered under the Oak tree on the front corner of my property along the street quite a few seedlings. Since the seedlings were mixed in with the Wintercreeper Euonymous under the Oak tree, I just let them to see what they would do. Well, last summer 2 purple and 1 pale pink bloomed so I dug up the 2 purple ones and left the pale pink one under the Oak by the road. I transplanted one (purple) on the side of my house where it is hot and dry and I put the other one in my back yard.  (I believe) the seeds came from my neighbor 4 houses down and across the street. She has a purple one but no one else on my street  has a Rose of Sharon that I have found.

Rose of Sharon, Althea, Hibiscus syriacus

Flower is done for the day

My double ruffle blooms around the 1st week in July and shortly after the others start to bloom. I have one in part shade and it has not bloomed yet but has buds. This is a late bloomer and would not be a good specimen tree for any garden because the leaves emerge much later than most other deciduous shrubs and trees. The Rose of Sharon does make a great hedge and I would think about mixing it in with some sort of conifer, evergreen, or arborvitae for winter interest. Rose of Sharon, Althea, Hibiscus syriacusThe Rose of Sharon can be controlled by simply cutting off thee seed heads before the pods turn brown and burst open. If the seedlings emerge, you can simply pull them out of the ground. I threw down seeds late last summer and this spring they emerged. These are fast growing plants. The first year they will grow less than a foot but by the 3rd year my Rose of Sharon tree has reached over 6′ tall. Now I live in zone 7 so I have a longer growing season and a milder winter but I would venture to guess that a foot a year growth until it reaches maturity is not over stating how fast they grow.

Rose of Sharon, Althea, Hibiscus syriacus

The seed pod burst and already released the seeds

The Rose of Sharon can be pruned to control its size. I am not a pruner so I let (most of my) plants do what they will. If you do want to prune I would wait until the last flower blooms and fall arrives to prune to shape for next year. You can also prune in early spring and shape the plant (some gardener says for bigger blooms). The Rose of Sharon can be a bush, tree, or even an espalier (which is training the plant to grow along a fence or wall).

Rose of Sharon, Althea, Hibiscus syriacus

Bee magnet

I have never fertilized my ruffled Rose of Sharon and had any disease problems but that does not mean they cannot succumb to blight, leaf spot, or canker. This year, however, there seems to be an aphid problem which I need to address with a shower of Dawn dishwashing liquid in my fertilizer hose sprayer. It has been written that the Rose of Sharon is also one of the favorites of the Japanese Beetle. (so knock on wood that I do not find this out)Rose of Sharon, Althea shrub seedlings, Hibiscus syraicus seedlings

There are new cultivars you can find at garden centers and nurseries which are smaller and are not invasive (because the plant does not produce many seeds). The bees love them which is a plus in my book. The Rose of Sharon also tolerates my dry, red clay soil and life under Oak trees which is another reason I have them.Rose of Sharon, Althea, Hibiscus syriacus

I have so many seedlings because I do not prune off the seed heads. It is easy to identify them and pictured below I have a close up of the leaves for you to use to identify them on your hunt. I would save the pictures and go for a walk in your neighborhood and see who has them. I would ask the gardener (or property owner) if they would mind if you took some seeds or dug up some of the seedlings. Many people will share and asking is so much better than just taking.

Rose of sharon Leaf

Leaf ID

I have transplanted these in the heat of summer with great success. Watering is the key to success and transplanting before, during, or after a rain is my secret. Happy gardening everyone and if you ever have a question, just ask.

Creating. Inspiring. Gardening without the rules!

Rose of Sharon, Althea, Hibiscus syriacus

Bloom bud and spent flower

2015 copyrighted material C Renee Fuller @the Garden Frog Boutique

Rose of Sharon single trunk

single stem to train as a tree

Rose of Sharon trunks

notice 2 trunks which will grow more into a bush

Rose of Sharon trunks

multiple trunks on my Ruffled Rose of Sharon

Rose of Sharon trunk

another small Rose of Sharon with double trunk

24 thoughts on “Beware of the Rose of Sharon (Althea) in your garden

  1. Great article, I rely really enjoy these plants. Have them all over our yard. Just planned them on our church grounds. We live in Mobile al.

  2. this article on rose of sharon was extremely helpful. you are a very good writer. i have understood more than from this article. thank you for sharing!

  3. Hi we just transplanted a 5 year old rose of Sharon and we did it right before a good soaking rain in the end of July in NJ. We have checked the soil and it has been moist and its in the shade. My leaves are drying up completely-not falling off yet, but it looks bad. Is it just stressed or is it dying do you think? We did put a bunch of garden soil around roots to give nutrients to clay soil.

    • There are probably two things going on with your Rose of Sharon. Stress which is causing the leaves to Brown up and if the roots lost the soil and you replaced it with the garden soil that might cause more stress. Rose of Sharon grow quite prolific in clay soil. As long as you planted it at the same depth as it was before and kept it well water but not dripping wet it should be fine. If it continues to decline I would dig it up and replant it and make sure that there’s no air pockets or holes around the roots and use the soil where the rose of Sharon is going to grow. Preparing the soil for planting can consist of just chopping up the clay soil to packet tightly but not too tightly around the roots. I would do this when the weather starts cooling down for you in your area. Write me for more information if you need to. Good luck

  4. I’ve had a row of multi colored Althea along the west side of my driveway for the past ten years. About every two years one or two plants split at the base while in bloom and have to be removed. I don’t know their lifespan and the ones that split are usually the older plants. Mine grow quite large and I do prune. Can they be topped at a certain age to prevent this? I live in zone 5. Thanks

    • I would top them now after they are done blooming. It is not going to hurt them. I find that here in zone 7 the lifespan varies because I have an 8 year old ruffled one which is looking quite leggy. Topping and pruning out the old wood will keep them looking good. I had a neighbor whose Rose of Sharon just died suddenly- with only 1 branch that is blooming and green. It was about 5 years old. If they are otherwise healthy, prune them down/top them so you can get a better shape for next year. plus do not put mulch at their base. Thanks for stopping by and good luck and happy gardening

  5. I have something strange going on with a Rose of Sharon bush in my backyard. It has always had both pale pink flowers with a red center as well as lavender ruffled blooms. I assumed that the previous owners grafted two together many years ago. But this year, dark pink ruffled blooms joined the party.

  6. I got 12 seeds from a friend. They were from the bush, a purple with a magenta center. 9 of the 12 grew. I now have 6 after giving 3 away. Out of the 6, 3 are the purple with magenta center, one is a pale pink with the magenta center and one is pure white. One has not flowered. They are 3 years old and I have the seed pods from all the plants. I have shared some. I am waiting for the all white and the pale pink to give up the seed pods this year for the friend who gave me the initial seeds as she has NEVER seen a white on!! Loved the article.

    • Nature has given me a white one and a darker purple Althea, but both are too close to the house😔 Hopefully they survive a move to another part of the yard.

      • The key is watering them every day for 30 days. I dug one up in JULY – the rose of sharon was 2 years old and about 6 ft tall and gave to a friend. It was a purple one. I told her it will wilt and look terrible for a while but keep it watered. She did and it bloomed despite being moved! The roots are not as wide as the branches reach and dig a little deeper- sometimes they are about a foot down depending upon how tall they are

  7. I ordered online what was listed as a “Red Rose of Sharon” with double blooms last year,It just bloomed this year and its a pink double bloom! I’m kind of upset because I was really looking forward to Red.My question is could it be I was lied to on the sale Or is it something to do with my Soil Ph?

    • I have never seen a red rose of Sharon I’ve seen a red hibiscus but not a Rose of Sharon. It has nothing to do with your soil’s pH. Is it a dark pink? Because maybe they think that is red. Otherwise I’ve only seen them with a white with a red Center purple with a red Center I just saw a white one that I’m going to try to go collect seeds I have a double ruffle pink one I mean purple but I’ve never seen a red one. I would write to the place that you got it and ask him if they sent you the wrong one. But again it is not your soil’s pH

  8. My Rose of Sharon is all big leaves and has grown into a big bush 6 ft tall,
    But has no buds and therefore no flowers.It is eighteen months old.Can anyone give me advice.?I Live on the Sunshine Coast Qld

    • It should bloom sparsely at 2 years experience in zone 7.I do not do anything special but start with Alaskan fish fertilizer and keep mulched. They bloom summer they do not life to be planted to deep either. Visit me at my Facebook page and send s pic to see if I can see anything obvious.

  9. I am considering this plant to replace my red Celia hibiscus that froze this winter. I am wanting the plant to be bushy and have green foliage from the soil upwards (obviously allowing for some trunk above the soil). I read somewhere that it is leggy and that that the foliage doesn’t grow near the soil. The plant would go in a container on my porch until it gets too big. How big are the blooms?

    • For a pot with blooms Rose of Sharon blooms are about 2-3″ but they are hard to keep bushy. For container blooms look at Tropical Hibiscus and you will have blooms all year (even inside in the right room). On a porch I am guessing it is bright light? then this would work perfect for tropical hibiscus. For fragrance- I would check out gardenias but they are finicky and sometimes not always predictable with blooms. Now if your porch is a medium to lower light I would look at hydrangeas! I love them but you want to look for a rebloomer but one of my favorite is mini penny hydrangea. hope these ideas helped you happy gardening

  10. I should probably mention that I live in central Texas. With that in consideration, when should I expect the plant to bloom if I purchased a 1 gal potted plant?

    • You should have some blooms this year. I have had Rose of Sharons blooms after 3 years and in your area (I am zone 7) they grow faster. Did it have a bloom when you bought it? If you bought it at a garden center then it probably had blooms at some point so I suspect you should get blooms this summer! Good luck!

  11. Thank you for your wise advice! I ended up getting a pink painted lady hibiscus at Lowe’s that is blooming well and has good form. I looked for an article about tropical hibiscus but didn’t see one. So… How should I pot it for success?

    P.S. I saw your article on Rose Rosette disease dot dot dot now I finally know what’s been making my rose bushes look so terrible. I rent and so I have to ask my landlord before I dig them up. My neighbor across the street has roses and I’ll make sure she knows about your article as well.

    • I found they like to be root bound and moist but not wet soil and fertilize 1/2 strength ever week. Bright room but not direct sun (morning or late day sun okay) I overwintered my tropical Hibiscus for 2 years.blooming will stop at times to rest but keep fertilizing. Ask if you ever need anything else

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