Rose of Sharon Invasiveness

brandon7 TN_zone(7)February 25, 2007

I recently received a whole bunch of Rose of Sharon seeds. I planted them and then decided to see just how invasive they are supposed to be. After doing a Google search, I am led to believe that they are highly invasive by seedlings in this area. Has anyone else grown these or found this to be true? Should I throw them out before they take over?

I was also wondering if anyone had any ideas about where to get cuttings of some of the sterile cultivars such as 'Aphrodite', 'Ardens', 'Diana', 'Helene', 'Jeanne d'Arc', 'Minerva', 'Morning Star', or 'Peaonyflorus'. I saw a number of nurseries that sold these cultivars as larger shrubs or small trees, but all I want are babies and I don't want to have to get a second mortgage on the house.

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intimidator_3(7a TN)

Im not sure which side to come down on with Rose of Sharon. Ive seen one at my moms place which has grown as a speciman for many years with no other seedlings around that I can tell. My next door neighbor also has one that has grown as a speciman for many years without taking over.

On the other hand, when I was just getting interested in gardening, My mother-in-law gave me a bunch she dug up from her yard to plant at our place which says that maybe they were a problem for her. I also have a large retention area beside the house that I rarely clean up. There are several wild Rose of Sharons in there that are around 6' tall and bloom every year. I never even noticed they were there until they bloomed.


    Bookmark   February 25, 2007 at 9:29PM
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anntn6b(z6b TN)

At our farm, there are four three large ones around the well house (the cats climb them to sun themselves on top of the well.) In ten years, I've had four volunteers come up within 200feet, and found homes for three of the four.

Now Privet Hedge is invasive!

    Bookmark   February 25, 2007 at 11:09PM
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I wouldn't consider RoS as "invasive" even with varieties that prolifically self-sow. The seedlings are incredibly easy to discern from other things growing and are easily pulled up and discarded or transplanted. When grown in a difficult soil, the seedlings aren't as abundant as when grown in a raised bed - so a lot depends on where the seeds fall and how easy it is for them to get a hold in the earth. The RoS seedpods are so blatant though, that you can easily let one flower to its heart's content and still go through and cut off all of the seedpods long before the seeds mature and the pod opens, or you can dead-head blooms, etc. I intentionally pull my grandmother's seedlings because they are heirlooms, and transplant them into containers to grow for the first year or three and then sell them as fundraising plants for the rescue work and/or transplant them out where I want them to grow. They are very versatile IMO... trainable for various forms, including bonsai, but my next intended project with them is as a hedgerow and keeping them cut to a lower height rather than having them develop into the tree-form.

No clue where you can find the varieties you're looking for... "sterile" isn't what I generally look for in any plant...

    Bookmark   February 25, 2007 at 11:16PM
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I have Blue Satin and and Rose Satin - both which self seed prolifically. But I do not have a problem with seedlings.

I also have a small Purpureus Variegatus but have never noticed seeds on it.

    Bookmark   February 26, 2007 at 10:38AM
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I had seven Rose of Sharon when I moved here 8 years ago and have seven today. Do they seed and spread? Have no idea. I mow the yard. Some of them have gotten a little too large for me so did a pretty severe trimming last fall. Will have to wait for the results.

    Bookmark   February 26, 2007 at 6:47PM
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brandon7 TN_zone(7)

Thanks for all the input. I guess they aren't as bad as I was worried about them possibly being.

The reason I was concerned is because where I will plant them (among other specimen trees and shrubs in a fairly large field), I won't be able to mow on a frequent basis and might not be able to devote the time needed to control an overly aggressive plant. I try to be somewhat environmentally responsible and didnt want to release a monster on the neighborhood. Sometimes "invasive" plants are no problem at all and sometimes they can take over a garden in no time (horsetail rush for instance).

    Bookmark   February 26, 2007 at 9:25PM
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Will you be "mowing" or bush-hogging? (noting the "field") Seedlings on up to plants of a couple/few years of age are relatively easy to pull up by hand if the soil will "let go". While RoS are relatively resilient when/if damaged, there is still only so much even a RoS can handle before it will give up on resurrecting itself. If you have some that come up and even if you let them go for a few years and then decide you don't like them where they are - if they are too thick in diameter to weed-eat/whack, mow, or bush-hog to cut, then just take a hand axe to the base and whack it down - into the "crown" of the rootstock (so you don't leave a sharp stob above ground that can puncture a foot, hoof, paw, tire, etc.) to axe/cut it out - don't cover it back up with soil, let it dry out that way if at all possible, to inhibit it potentially coming back from the rootstock. RoS have a true taproot, though they (the taproots) are quite capable of adapting to their terrain and can grow "sideways" over bedrock, etc. if need be to get a hold, but severing that taproot has always been effective for eradicating an undesired specimen IME.

The self-sown seedlings are *very easy* to identify - the seedling leaves are virtually identical (except for initial size) to that of mature leaves - so you can visually pick them out from even a radically mixed genera field, bed, etc.

Think ahead of time how you would like them to look. If you want single-trunk tree-form for instance, be on the look out for multiples from a single seed early on, and prune any lower branches that you don't want before they get thick (saves pruning later and helps RoS to dedicate energy to upper level growth), etc. Consider whether or not you might want to "weave" top growth together for arches or other "designs". Do training when branches are new/young for the longterm. If you want each one to be an "eyecatcher" - provide them with plenty of space between one another. If you're not sure, you can always cull out specimens "in between" later on.

Planted 3' between one another and either "woven" together or allowed to grow naturally, they can make a fair windbreak and/or relatively good privacy when in leaf and visual interest in the winter (another plus when they are trained or pruned with design in mind). You can prune one or both faces ("front" and "back") for a more uniform appearance if row-planted and encourage lateral growth along the "line" you decide upon.

If you start from seed in containers, you can grow several in one container for a couple of years, protect the container/root area in winter (south side of a house, building, wrap the container, whatever) and then after a year or two (or longer if you like), transplant out into the ground and you shouldn't even have a need to mulch them. (seedlings do like to crop up in mulch - but are easy to pull out of it). The young plants don't seem to mind even rough treatment when separating multiple root systems when rootbound in a single container together.

They will grow in the worst of rocky, clay soil with no water save rain, but growth is distinctly slower. The best specimens up here (best in respect to growth rate, etc.) have about a half-day of sun - one group mid-morning to early afternoon, another strictly afternoon sun, the most impressive group a couple hours of full sun and then dappled shade from towering Oaks. If you sow/plant near running water, they should be happy as larks, but you can probably expect some seeds later on to catch a ride with the water and not be surprised to find some RoS growing semi-aquatic along the banks. Birds don't seem interested in the seeds, but I have seen some curious type of insect in opened pods - not sure if they were eating seeds or just using the open pods to breed, hatch, or what exactly. I've only seen that once. No foliage damage or anything like that and no bad weather, so I don't think they were using the open pods for shelter. On insects and RoS though - nice plant to re-direct Japanese Beetles to in lieu of actual roses or other plants that don't recover as quickly when the JBs strike en masse overnight.

    Bookmark   February 27, 2007 at 12:59AM
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