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Different weeds late in year??? #679200 - Ask Extension

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Different weeds late in year??? #679200

Asked January 20, 2021, 10:44 AM EST

These weeds suddenly popped up in all of my gardens late fall. Also creeping Charlie took over late in season like gang busters!!! I thought I had seeded and then this stuff popped up that I had never seen before. I am pretty horrified. Will they die down over this winter or am I going to be weeding yet two more weed species this spring.

Baltimore County Maryland

Expert Response

The weed in the photo looks like Hairy Bittercress, a very common winter annual. Such plants germinate in the cool weather of autumn and persist through the winter, resuming growth in spring when they flower and set seed. (This can also happen during winter in mild weather.) After producing seed, and with the warmth of late spring, the plants die. Control of future seed germination needs to occur in late summer or autumn; for now, the focus is on preventing the plants from setting seed to reduce the seed bank that is built up. Here is more information on this plant: https://extension.umd.edu/hgic/topics/hairy-bittercress If there are no desirable plants currently in this garden bed, smothering the weeds by blocking their light is probably the simplest, lowest-impact approach. You can use a thick mulch layer (like wood chips) or a barrier like landscape fabric (which is removed upon planting).

For the Creeping Charlie (a.k.a. Ground Ivy), control may take more steps. As a perennial which also roots as it creeps, it is more challenging to remove due to its more extensive resources and stored energy. If repeated vigilant removal or smothering isn't effective, resorting to targeted use of systemic herbicides may be the most direct way to gain the upper hand. https://extension.umd.edu/hgic/topics/ground-ivy

If these weeds are problematic among desirable plants which cannot be covered and are at risk of spray damage, physical removal is the best choice. Though tedious, preventing seed-set and continually removing runners will deprive the seed bank and the remaining plant tissues of reserves that will contribute to future problems. Eventually, as surrounding desirable growth helps to cover exposed soil, weeds will be less successful at infiltrating the garden.

Miri

Mira Talabac Replied January 20, 2021, 12:31 PM EST

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