Fall Weed Control: Why Autumn Is the Best Time to Stop Weeds for Good
Weeding in the months of October and November is worth more than all the weeding you can do in the spring․ Most of the weeds found in the average garden in Tennessee are either going to seed for the next generation‚ or they are storing energy in their roots to come back growing like crazy in March․ Hit them now‚ and you're not just cleaning up‚ you're destroying next year's weed population before it can even get started․
Here in Zone 6b/7a that window is from late September until early December depending on when your first hard frost strikes․ You have a good two months of workable soil‚ visible weeds and no 90-degree days to pull weeds before winter closes in․
Why Weeding In Fall Actually Works Better Than Spring
Most amateur gardeners think of weeding as a spring task‚ presumably since that's when a garden can look most overgrown all at once․ In fact‚ they cannot be stopped in the spring․ Either they will have germinated from seeds that fell the previous fall‚ or they will have put forth new shoots from the root systems which survived the winter quite nicely‚ thank you․
Fall then gives you a head start․ Cool season annual weeds like henbit‚ chickweed and annual bluegrass are germinating in September and October right now and will overwinter as small seedlings․ You pull them out before they've even had the chance to flower and set seed the next spring․ And the perennial weeds‚ like dandelion‚ plantain and wild violet are pulling that energy down into their roots to make it through winter․ If you are treating with a herbicide‚ at this time the plant is most likely to translocate the chemical to the roots where it can be absorbed for a much more complete kill than summer treatments․
However‚ the mechanical advantage of time‚ rains at the end of the growing season in Tennessee coming over a longer period of time‚ would have kept the soil moist long enough to pull the entire dandelion up by the taproot․ Put that in the ground in August heat‚ and you'd break the root off at the crown‚ leaving enough to resprout․
Fall weeding is costly to skip․
The biggest problem is that crabgrass heads will produce 150‚000 seeds and if a area covered with a patch of chickweed goes to seed in October‚ and then that area is thawed out in the spring‚ you'll have more than a weed problem‚ most of which are going to be in the same area as your perennials‚ you'll have a carpet of weeds‚ hand pulling them is time-consuming․
One hour of weeding in November saves five or six hours of fuming when‚ come April‚ the weeds are elbow-deep around the crowns of your daylilies and hostas․
Manual Weeding: Still the Best Tool for Most Situations
With smaller beds hand-pulling is also the best way to go․ If you wait until the end of fall rains‚ or do your pulling first thing in the morning when the dew has softened the soil‚ you will readily pull the roots out cleanly․
There are a number of factors that make fall hand-weeding desirable:
- When digging up a plant with a taproot (such as a dandelion) with a hori-hori knife or dandelion fork‚ the top is often the only part that comes off without the whole root being pulled․ - Wait for the rain to subside‚ ensuring soil is moist and soft but not muddy for easier removal․ - Bag or hot compost any material which is or possibly has flowered‚ seeded or carried seed-bearing weeds to a cold composting pile․ Most seeds survive this process just fine and you'll be spreading them right back into your beds come spring․ - Do it section by section․ Trying to weed the whole yard in one afternoon just leads to weeding fatigue‚ sloppy pulling and half-unearthed roots․
Mulching: Your Fall Weed Barrier for Next Spring․
This is the stage most people skip that does the most work for the long term․ If done correctly‚ the mulch will block the sunlight completely‚ like a blanket‚ from any weed seeds in the surface topsoil that may be dormant․ Fewer weeds will germinate in March and April․
Unlike inorganic mulches like landscape fabric‚ a natural organic mulch (i․e․ shredded hardwood mulch‚ straw‚ shredded leaves) spreads a more natural aesthetic and can be 2-4 inches both in-between and 2-4 inches from the stems of plants or the trunks of trees to prevent rotting as well as being chewed by rodents․ TN Nursery's straw and leaf mulch will break down over the winter‚ feeding your soil․
However‚ one thing I rarely hear about fall weeding is how important it is when you put a mulch down‚ not how much of it you put down․ If you put it down while the soil is warm and those weed seeds are trying to germinate‚ all you've done is trap what they need to survive․ Wait until your first light frost‚ when the soil temperature and mulch (which once provided a greenhouse effect) are too low to support germination․
When to Apply Fall Herbicides and How
Chemical control is generally not needed in most home gardens‚ but may be attempted on large or established populations if applied late in the season․ Late in the season the plant is moving energy from the plant's leaves into the root to prepare for winter․ A systemic herbicide applied then will likely be translocated down into the plant's root system and kill the entire plant‚ not just those green above ground․
If you want to do this:
- Apply on a day when rain is not expected for at least 24 hours‚ so that the product will not be washed off before it has time to sink in․ - When weed eating large areas‚ such as your lawn or a flower bed‚ use selective herbicides - broad-spectrum herbicides destroy all plant life․ - Do not spray newly planted perennials and shrubs‚ or the root zone of newly planted material from TN Nursery or a local nursery‚ as the younger roots are more susceptible to herbicide drift and injury․
Putting It Together: A Realistic Fall Weeding Timeline
Annual weed seedlings can be pulled and discarded as soon as they appear‚ in late September through early October; perennial weed seedlings can be pulled out in mid-October when the soil is still soft and before the first hard frost․ (October through November: Mulch the garden as soon as the soil has cooled and before the first hard frost; identify and treat perennial weeds with herbicides․) Onset of frozen ground in early December is a natural stopping point until a clean-up in late winter․
Otherwise‚ I can guarantee that the spring in this garden will be harder‚ because when you open your garden beds in March‚ you'll find all manner of things in them that you didn't put there․
