Do you fight weeds in your gardens? You’re not alone! Every year weeds pop up in our gardens and it can be hard to keep them under control. There are several pre and post emergent herbicide options on the market, but that’s not what I’m covering today. I’m going to look at some common garden weeds and the number of seeds one plant produces. When we start to think about the number of seeds that weeds produce, we soon realize why they are such a problem to control.
Redroot pig weeds produce 13,000 – 35,000 seeds per plant and it takes 3 years for the seedbank to be reduced by 50% and about 20 years to deplete the seedbank by 99%.
Giant ragweeds produce 10,300 seeds per plant and it takes 2 years to deplete the seedbank by 99%.
Common ragweeds produce 3,500 seeds per plant and it takes 1 year to deplete the seedbank by 50% and 10 years for 99% depletion.
Velvet Leaf produces 2,000 – 9,000 seeds per plant. Each plant produces about 70 – 200 seed capsules per plant and each capsule contains 35 -45 seeds. It takes 2 years for the seedbank to be reduced by 50% and about 16 years to deplete it by 99% unless it is buried deep in the soil from plowing and it will persist longer.
Common Lambsquarters produces between 30,000 – 176,000 seeds per plant and takes 12 years for 50% depletion and 78 years for 99% depletion.
Giant Foxtail produces 500 – 2,500 seeds per plant and takes 5 years for the seed bank to be reduced by 50% and 30 to deplete it by 99%.
Canada Thistle will produce between 1,500 and 5,300 seeds per plant and research shows low to moderate persistence - when buried 1 to 3-inches in the soil 45 to 60% of seed germinates the first year and less than 1% survives after 3 to 5 years. When buried at greater depths (7-inches or more) and left undisturbed seeds have been found to be viable for up to 30 years.
Hairy Galinsoga can produce up to 7,500 seeds and can remain viable for more than 2 years.
Next time you see a weed getting ready to spread it’s seeds think about these numbers and cut it down before it can spread it’s offspring all over your yard and gardens. If you are experiencing issues with weeds that I didn’t mention drop me a line at jagger.6@osu.edu to share what your problem weeds might be.
Sources: Michigan State Department of Soil and Microbial Sciences, Weeds
https://www.canr.msu.edu/weeds/extension/michigan-s-worst-weeds
https://blogs.cornell.edu/enychp/vegetables/weed-of-the-week-hairy-galinsoga/