Sweet clover in the rain

Tuesday it rained all day; perfect weather for pulling sweet clover!

Tuesday is our "intern day". Despite the rain, the interns were out in force, dressed for the weather. Amanda worked right along with them and they pulled all the yellow sweet clover they could find, on the Valley Prairie and on the south-facing slope. (I built a fire in the cabin so they could dry off at lunch.)

Most of our sweet clover is white, but for some reason, at the east end of the south-facing ridge there is substantial amounts of yellow. Not surprising, the Valley Prairie, which is down hill, also has yellow instead of white.

This early in the season, any flowering plants pulled can be left on the ground, since they will not go on to make seed. Later on, when the flowers are starting to make seed, we bag the plants and take them off the site, since some may go on to produce viable seed.

Because it is a biennial, sweet clover may be worse one year than the next, although after a while this phasing becomes less pronounced. Newly burned areas often show a large flush of first-year plants the year of the burn. Left alone, these plants will all go on and flower the next year and set seed.

Patches of sweet clover too large to pull can be mowed, but the timing is tricky. If you mow too early, they will resprout and go on to flower, If you mow too late, seed formation may have already started, in which case you have to remove the plants from the site, a large chore in itself.

One sweet clover phenomenon we discovered at Black Earth Rettenmund Prairie is a new flush of growth in the early fall. These fall plants are very short, but still have flowers. Because they are short, they may be missed among the generally tall prairie plants. We discovered this fall-growth phenomenon when collecting seeds, and found ourselves wasting a lot of seed collecting time pulling these little, but flowering, plants.

I don't know how long it takes to eradicate sweet clover from a site. We have been pulling it at Pleasant Valley Conservancy for over 10 years and haven't eliminated it yet.