Rose of Sharon (Hibiscus syriacus), also known as shrub althea, is a very common deciduous shrub that is grown in USDA hardiness zones 5 to 8. It gains its name from the blooms, which some people find reminiscent of the prolific blooming pattern of shrub roses. In reality, this plant is a member of the mallow family and viewed up close, its flowers more closely resemble those of hollyhocks or hibiscus. This rangy shrub grows up to 12 feet tall and blooms vigorously from early summer and into the fall, and therein lies the problem. Many flowers mean many seeds, and rose of Sharon is known to self-seed prodigiously, which can result in dozens if not hundreds of volunteer seedlings that spring up all around the garden and lawn. These seedlings are fast-growing, with the result that rose of Sharon can be severely invasive if you dont take measures to control its spread.
Its also possible that you might want to grow some rose of Sharon plants into mature specimens. If so, the ease with which these plants self-seed also makes them very easy to propagate intentionally.
Rose of Sharon is a popular flowering shrub commonly grown for its attractive blooms that appear in late summer. However, this plant is notorious for readily self-seeding and producing an abundance of volunteer seedlings that can quickly get out of control. If your yard is suddenly overrun with rose of sharon sprouts, here is a comprehensive guide to effectively eliminating them for good.
Why Rose of Sharon Spreads Aggressively
There are two key reasons why rose of sharon (Hibiscus syriacus) tends to spread invasively via self-seeding
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Prolific blooming – Few flowering shrubs can match the sheer number of blossoms produced by rose of sharon from early summer into fall. More flowers mean more seeds
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Efficient seed dispersal – The small seed pods that form below each bloom split open when ripe, allowing seeds to drop near the parent plant. Winds and rain also spread seeds further afield.
Once on the ground, rose of sharon seeds germinate readily to produce fast-growing seedlings. Within a season or two, they can reach over 6 feet tall. Left unchecked, rose of sharon will form large thickets or colonies. While some may appreciate self-seeding shrubs for their low maintenance, most gardeners view the seedlings as weeds. Fortunately, there are several effective control methods.
Manual Removal Techniques
Hand Pulling and Digging
Manually uprooting seedlings is labor-intensive but avoids herbicide use. Small seedlings can be hand pulled, while larger ones will need digging out with a trowel or shovel.
Tips for manual removal:
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Wear gloves to protect your hands from thorns on stems.
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Use a garden fork to loosen soil if seedlings don’t pull out easily.
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Shake or rinse all soil off roots to prevent regrowth.
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Focus on seedlings growing in lawns or garden beds. Remove those in natural areas only if invasive.
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Hand pulling is easiest when soil is damp but not soggy. Use a weeding tool for leverage on stubborn seedlings.
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Removing them as soon as they appear in spring is best.
Smothering Seedlings
Covering areas where seedlings are growing deprives them of light and smothers them within a month. Options include:
- Tarps or plastic sheeting
- Cardboard or layered newspaper (wetting paper speeds the process)
- Natural materials like wood chips, mulch, or pine needles
You can even solarize areas by moistening soil then covering with clear plastic for several hot weeks. Just be sure to remove desired plants first.
Applying Pre-Emergent Herbicide
Pre-emergent herbicides like Preen prevent seeds from sprouting but don’t kill growing plants. Use around established rose of sharons to stop seedlings from emerging.
Key tips for pre-emergents:
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Apply in spring before seeds germinate. Time a late summer application for any new seeds.
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Reapply after heavy rains which can wash away products.
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Avoid spraying near wanted plants—herbicide will prevent those seeds from sprouting too.
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Read and follow all label directions carefully to avoid lawn or plant damage.
While pre-emergents offer effective control, hand pulling may be a better choice for gardens with frequent seed starting.
Using Post-Emergent Herbicide
Non-selective, post-emergent brush killers will destroy any existing woody seedlings. Glyphosate products like Roundup are effective. Other options include triclopyr and 2,4-D.
How to safely use post-emergent herbicides:
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Spot treat individual seedlings rather than broad spraying, which can harm other plants.
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Apply carefully to leaves with a paint brush or targeted sprayer to avoid drift.
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Never use near desired trees or shrubs—these products kill any plant they contact.
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Follow all label precautions to avoid environmental or personal harm.
Repeated hand pulling is labor intensive but eliminates the need for herbicides in home gardens. Consider removal options first.
Prevention Is Ideal
Stopping seeds from forming in the first place is the best approach. Here are two simple preventive methods:
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Grow sterile cultivars like the Chiffon series that don’t produce seeds.
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Deadhead spent blooms and developing seed pods before they mature seeds.
Vigilant deadheading through the season will halt self-seeding. But existing seedlings also need removal using techniques above.
Be Persistent and Patient
Eliminating unwanted rose of sharon seedlings requires dedication over time. Hand pull emerging seedlings each spring before they get large. Herbicides provide chemical control but should be used judiciously. Combined with prevention measures, your effort will pay off in stopping the spread.
While rose of sharon can be invasive, totally banning a beloved flowering shrub is not always necessary. Instead, control self-seeding around your property and in natural areas where it could crowd out native plants. With smart integrated management, you can still enjoy the beauty of rose of sharon blooms without the nuisance of its progeny.
Frequently Asked Questions
What is the best way to get rid of rose of sharon seedlings?
The most effective way is to manually dig up and remove the seedlings, including the root system, as soon as you spot them. For larger infestations, using an herbicide formulated for woody plants can help kill off seedlings.
When is the best time to remove rose of sharon seedlings?
It’s best to remove seedlings in early spring when the soil is moist and they are small. This makes pulling them easier and prevents further spreading.
How do I stop new rose of sharon seedlings from growing?
Prevent seeds from forming by deadheading spent blooms before they set seed. You can also apply pre-emergent herbicide around mature rose of sharons which will stop seeds from sprouting.
Will rose of sharon seedlings continue to come back if I don’t remove the roots?
Yes, any remnants of rose of sharon roots left in the ground can resprout and produce new seedlings. It’s critical to remove the entire root system when digging up seedlings.
Is it possible to just mow down rose of sharon seedlings?
Mowing will temporarily control the height but won’t kill rose of sharon seedlings. They will continue to re-sprout unless fully removed root and all.
How do I dispose of pulled up rose of sharon seedlings?
Place the pulled seedlings into yard waste bags for disposal, being sure to shake off all excess soil so they don’t re-root. Do not compost rose of sharon plants.
By taking a multifaceted approach of manual removal, herbicide application, and prevention, you can get unwanted rose of sharon seedlings under control. With persistence over time, you can eliminate this aggressive invader and reclaim your landscape.
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Practice Manual Removal
Pulling seedlings by hand is the most time-consuming and difficult way to deal with volunteer seedlings, but it is also the most environmentally friendly. Spotted early, the seedlings arent difficult to pluck from the soil. Larger seedlings are a bit more difficult, as the root systems develop quickly, but they still easy enough to dig up with a trowel or shovel. You really dont need to bother with seedlings that sprout up in the lawn, because regular mowing will soon cause them to fade away.
Apply Preemergent Herbicide
Some classes of chemical herbicides are intended to be preemergent, working by preventing seeds from germinating in the soil while not affecting existing plants. Products such as Preen are of this type. A preemergent herbicide applied on the ground around a rose of Sharon bush will prevent its seeds from germinating and taking root.
Be aware, though, that these preemergent herbicides generally work on all seeds, including those you deliberately plant in the garden. Applying a preemergent herbicide will prevent all seeds from taking root, whether they are wanted or unwanted. It is generally best to try non-chemical means of preventing self-seeding before reaching for a herbicide.