Dock weed (Rumex obtusifolia) goes by many common names, including broad-leaved dock, bitter dock and celery seed. Its seeds germinate easily, allowing this weed to appear in lawns and gardens everywhere. Dock weed can be difficult to pull up by hand, and it can also be difficult to kill dock weed with gentle products, so it requires a different eradication strategy.
Removing Dock Weed by Hand
One way to get rid of dock weed or any weed involves removing the root system. This prevents the plant from sprouting up from any leftover roots. The trouble with dock weed is that its tap root can extend up to 4 feet underground.
However, research indicates that only the upper 3 inches of dock weed's tap root is capable of sprouting a new stem. If you can dig out the root at least 3 inches below the soil line, you should be able to kill dock weed with ease.
It's easier to dig into moist soil, so wait until after a rainfall to dig up dock weed on your property with a shovel or hand trowel. Deposit the root pieces into a yard waste bag or burn pile. Do not compost it since it may just resprout in your compost pile. Look up what young dock weed looks like so you can easily identify it and pull it up before its tap root locks into the soil.
Broadleaf Herbicides for Dock Weed
Dock weed's ability to resprout from the top 3 inches of its root makes it difficult to use nonchemical weed-killing methods. For example, torching dock weed may kill the current leaves, but it won't slow down the plant's regrowth. The same is true of dumping boiling water or vinegar on dock weed.
Therefore, chemical herbicides represent one of the few effective options for controlling dock weed. Products containing trifluralin have been reported to work especially well on dock weed. In theory, all herbicides intended for broadleaf weeds will also kill dock weed. Remember to read the label very carefully and follow all safety precautions before handling or applying an herbicide. This includes wearing appropriate personal protective equipment, mixing the herbicide correctly and applying it under the recommended weather conditions.
Preemergent Herbicides to Control Reseeding
Dock weed produces numerous seeds that spread easily and germinate rapidly. If you live near pastures, crop land or unkempt properties where dock weed often goes to seed, you may find yourself constantly battling new dock weed sprouts. Consider applying a preemergent herbicide to prevent these seeds from growing into fresh dock weed plants.
Products that contain isoxaben have been noted to effectively keep dock weed at bay. Wear eye goggles, long sleeve shirts and pants, a respiratory mask, and gloves when applying isoxaben preemergents.
Outcompeting Dock Weed
Once a new dock weed plant establishes its tap root, it can grow up to 5 feet tall and dominate the landscape, but as a seedling, dock weed has a weakness: It is vulnerable to competition from other plants. You can take advantage of this by ensuring your lawn or garden is kept full and lush. For example, overseed the lawn and keep up with an appropriate fertilization schedule to ensure it stays healthy enough to crowd out any dock weed sprouts.
If part of your yard or garden will be left bare for a while, cover it with landscape fabric. Any dock weed seeds that land on it will not be able to germinate. Take care not to allow dirt to collect on top of the landscape fabric so that this remains an effective strategy.