Attacking Perennial Weeds in Fall: Find Them, Dig Them, Starve Them - Ep 325

Perennial weeds live in their roots, and fall is when those roots are filling up for winter. That's why you hear so much about fall being weed-killing season. But if you garden without herbicides, the real value of fall is a little different. It's the season to find these weeds while they're easy to see, dig the ones you can dig while the soil is soft, block the light on the ones you can't, and set yourself up to hit them next spring when their roots are at their weakest. In this episode I'm walking you through why perennial weeds keep coming back, and what the research says about the popular fixes, including vinegar sprays, cardboard and mulch, tilling, and counting on a hard freeze. Then I'll give you a fall and winter game plan that changes depending on whether your winters are frozen, moderate, or mild. And then we'll go weed by weed through bindweed, Canada thistle, Johnson grass and Bermuda grass, nutsedge, dandelions, and poison hemlock. Let's dig in! Get a quote for your personalized garden consultation: https://justgrowsomething.com/gardenconsulting Get your fair-trade, organic coffee and support the show at https://LarrysCoffee.com/JustGrow References and Resources Nebraska Extension in Lancaster County (Browning) — Fall Weed Control (perennials move carbohydrates to roots in fall; fall control of annual weeds is unnecessary): https://lancaster.unl.edu/fall-weed-control SARE (Mohler, Teasdale, & DiTommaso) — Manage Weeds On Your Farm: Canada Thistle (lowest root reserves at ~1-foot shoots and flower bud; 21-day weeding schedule; exhaust roots within two years; loose mulch ineffective, tough tarp effective; surface root fragments killed at 14–21°F; fall cover grains favor thistle): https://www.sare.org/publications/manage-weeds-on-your-farm/canada-thistle/ SARE (Mohler, Teasdale, & DiTommaso) — Manage Weeds On Your Farm: Bindweeds (lowest reserves at 12–28-inch stems with 4–6 leaves; roots withstand 21°F; hedge bindweed through 18 inches of bark mulch; 2-inch root piece produced 25 shoots in four months and spread 9.4 feet in 15 months; forage soybean shade; fall-planted cover crops): https://www.sare.org/publications/manage-weeds-on-your-farm/bindweeds/ SARE (Mohler, Teasdale, & DiTommaso) — Manage Weeds On Your Farm: Johnsongrass (lowest reserves 10–30 days after emergence at 6–12 inches; late-fall tillage won't prompt sprouting; rhizomes die below ~16°F daily minimum soil temperature; freeze-kill varies year to year; shattercane lacks rhizomes): https://www.sare.org/publications/manage-weeds-on-your-farm/johnson-grass/ Oregon State University Extension, Ask Extension (Bubl) — Does vinegar help with controlling weeds? (contact action, perennials hardest to control; homemade vinegar–Epsom salt–soap test on Canada thistle): https://extension.oregonstate.edu/ask-extension/featured/does-vinegar-help-controlling-weeds University of Maine Cooperative Extension (Lounsbury, Birthisel, Lilley, & Maher) — Bulletin #1075, Tarping in the Northeast: Types of Tarps and How They Work (annual weeds killed in under a week in summer, up to three weeks in cool seasons; perennials knocked back but not eliminated by under six weeks; nutsedge resistant; ~10% of farmers saw some weeds worsen; no regional research on long tarping and perennial bud banks): https://extension.umaine.edu/publications/1075e/types-of-tarps-and-how-they-work/ Oregon State University Extension (Filley) — EM 9652, Tracking weeds is first step in controlling them (weed mapping, weed calendaring, identification through Extension): https://extension.oregonstate.edu/catalog/em-9652-tracking-weeds-first-step-controlling-them Colorado State University Extension (Beck) — Canada Thistle (roots 15+ feet horizontal, 6–15 feet vertical; 0.25-inch root pieces regrow; shoots emerge ~15 days after tillage; pieces survive 100 days; fall flush; seedlings perennial at 7–8 weeks): https://extension.colostate.edu/resource/canada-thistle/ Purdue University Extension (Fry, Stout, Griffin, et al.) — FNR-647-W, Johnsongrass Control (seedlings form rhizomes in 19 days; heavy fall tillage exposes rhizomes to killing cold; light fall tillage spreads them): https://purdue.edu/fnr/extension/wp-content/uploads/2025/04/FNR-647-JohnsongrassADA-final-comp.pdf UC Statewide IPM Program — Pest Notes: Bermudagrass, Publication 7453 (rhizomes usually 1–6 inches deep; black plastic 6–8 weeks in summer; plastic in winter ineffective; solarization 4–6 weeks during high sun; early-spring solarization can promote growth; wood chips ineffective without fabric): https://ipm.ucanr.edu/home-and-landscape/bermudagrass/ UC Statewide IPM Program — Pest Notes: Nutsedge, Publication 7432 (remove before 5–6 leaves, every 2–3 weeks in summer; tubers survive 1–3 years; 60% and 20% reserve use; resprout 3+ times; dig 8–14 inches; plastic ineffective; nonwoven fabric works; thrives in waterlogged soil): https://ipm.ucanr.edu/home-and-landscape/nutsedge/ Just Grow Something: https://justgrowsomething.com Gardening Courses: https://justgrowsomething.com/courses Just Grow Something Merch and Downloads: https://justgrowsomething.com/shop Just Grow Something Gardening Friends Facebook Group: https://www.facebook.com/share/g/18YgHveF5P/ Check out how you can become a patron on Patreon: https://www.patreon.com/JustGrowSomething Feed my coffee habit: https://buymeacoffee.com/justgrowsomething Amazon storefront: https://www.amazon.com/shop/justgrowsomething Hosted by Simplecast, an AdsWizz company. 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