Like many of you, I’ve been busy planting and seeding in my personal garden and in the demonstration garden here at the fairgrounds. Since the best weed management strategies are preventative, I’m also working on weed management. A few things that help me get ahead of the weeds are stale bedding and occultation tarps.
With stale bedding, I run irrigation on a bed about two weeks before I plant into it, killing off the annual weeds with a hula hoe or stirrup hoe. This only disturbs the top ½ inch of the soil, so by irrigating it I am encouraging the weed seeds in the top layer of the soil to germinate, and then I hula hoe and kill those weeds after about a week, or when I start to see tiny weeds in the “thread stage,” when their stems are tiny and delicate. I try to do this two times before I plant – I don’t always make that happen, but it really helps to reduce the weed pressure if I can.
Using occultation tarps is a similar process – I irrigate a bed and then put a black silage tarp over it for a couple of weeks. The tarps are thick enough to block out all the light, and I put them down with the black side facing up so that they heat up the soil. The warm wet conditions encourage the weed seeds on the surface to germinate, and then they die without light, also decreasing the weed seed bank in the top layer of the soil. I have had the most success when I run drip irrigation underneath the tarp, but when I can’t do that, it has still lowered my weed pressure to water it well and tarp it for a couple of weeks. Be sure to weight the tarp down well with rocks or sandbags, or you’ll end up chasing it down after spring winds.
With both techniques, it’s important not to till after you complete it, because that would turn up a new batch of soil with the weed seeds that are in there. These take some planning ahead, but I find it saves me time, especially before seeding carrots, spinach or beets that take a long time to germinate. They usually save me one round of hand weeding on each crop.
I also recommend doing this if you are seeding native grasses or wildflowers, especially if it’s on disturbed soil with some weed pressure. We are seeding warm-season grasses like blue grama now through mid-August, which will stay green in the summertime in the future, while being brown and dormant until midspring. We seed them in a mix with cool-season grasses like western wheatgrass, which will green up earlier next year.
Once you have weeds under control, the snow is off Methodist Mountain and the usual last frost dates have passed in Salida and Buena Vista, so as long as there’s no frost in the 10-day forecast, I start planting my tomatoes and other tender crops. I recommend keeping some row cover over them when you first put them out to help them harden off and adjust to full sun and cold nights. Row cover does also speed up weed growth, so be sure to take it off and check on the plants often, and remove it at least once you see the first flowers to ensure good pollination.
We encourage gardeners and artists to participate in the Chaffee County Fair Open Class. Bring your entries, from flowers to veggies, photographs to cross-stitch, from 9 a.m. to 3 p.m. July 26 at Chaffee County Fairgrounds.
Bring gardening questions to the Chaffee County CSU Extension office: 185 Quigot Court, northwest corner of Chaffee County Fairgrounds. Open 7:30 a.m.-5:30 p.m., closed noon-1 for lunch, Monday through Thursday. You can also reach us at 719-539-6447 or monica.pless@colostate.edu.
Monica Pless is Chaffee County’s director of Colorado State University Extension.