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Using hoes for maximum weed control
By Josh Volk
Selecting a good tool and keeping it in working order is only one piece of any job. While it is a critical piece, it cannot be separated from the need to understand how the tool works. There are a lot of aspects to the way a tool works: timing, the physical manipulation of the tool, and also recognizing the limitations and even drawbacks of the tool, recognizing when not to use it.
In my experience timing is one of the most difficult tricks to master. The difference between a sharp blade and a dull one is fairly obvious once you get the feel, but timing seems to always be a bit of a guess that has to also be balanced with all of the other tasks on the to-do list that always seem to take precedence like planting, harvesting, and irrigating.
Early and often has become my mantra with weed control. Putting off hoeing lets the weeds get bigger, and usually that means they are both harder to kill with the hoe and harder to distinguish from the crop. Both of these things add up to extra time, and it takes significantly more time to hoe a crop when you can’t clearly see the crop through the weeds than one where you can hardly tell the weeds are there yet. Also, bigger weeds compete more with the cash crop and in some crops, like lettuce, they can significantly affect the quality.
I figure it takes most weeds less than a week to germinate and about another week to start developing true leaves. The easiest time to kill them is after they’ve just poked their cotyledons out, and before they have true leaves to start putting energy back into the roots. Similarly, with perennial weeds like grasses, the new, tender shoots are much easier to hoe back than established stems. Knocking back perennial weeds while they are young helps deplete the roots of energy. For me, the most critical hoeing is the week after planting and I try not to put that off for other tasks by more than a week.
In many cases, if the bed has been well prepared (see my article on bed preparation in GFM September 2008), I’ll be hoeing a bed where I can’t even really see any weeds yet, but this doesn’t matter to me, in fact it’s what I’m looking for. If I can’t see the weeds yet, I can very quickly slide the thin blade of a very light hoe through the surface without hesitating or being stalled by stems of weeds. I won’t even have to stop to clear my blade unless the soil is particularly wet or sticky. I go over the entire bed surface, minus the seeder track if it’s a direct seeded crop, and avoiding the transplants if it’s a transplanted crop, whether I see a weed or not. Speed is more my concern than thoroughness at this early point. Even if I miss 5% of the weeds the ones I missed will still be much easier to hoe out with a second hoeing than they would have otherwise, and a second hoeing is almost always necessary to deal with a second flush of weeds anyway. By hoeing early I can do two or three hoeings in less cumulative time than a single hoeing through large weeds. I’ve also broken up the hoeing into more manageable chunks of time that can fit into smaller breaks in the day.
There are many other advantages to hoeing early as well. By loosening the surface and incorporating air, the soil to seed contact is broken and weed seeds near the surface won’t germinate as well. Breaking the capillary action of the soil at the surface reduces surface evaporation which leaves more water available for the crop. You are also doing two other things: you are incorporating some air which helps soil microorganisms break down more nitrogen from the organic matter in the soil, giving your crop a small shot of nitrogen, and you are allowing future rains or overhead irrigations to infiltrate the soil more easily.
In order to leave the surface loose I alway hoe walking backwards, in order to cover my foot prints. I also try to work within the top inch or two of the soil surface, less with particularly shallow-rooted crops like onions. If you’re killing annual weeds when they are young they won’t come back from the roots. If you’re waiting until they are older, in most cases I still think it’s better to cut them off near the surface rather than to disturb the cash crop roots in the process of pulling or digging them out. Repeated hoeing at one to two week intervals keeps re-sprouting roots from becoming a problem in the crop.
Making time to hoe early is one challenge, timing hoeing around moisture is another challenge. A hot dry afternoon with a bit of a breeze is the best time to kill weeds. This will desiccate the weeds before they have a chance to re-root. Dry soil also flows better around the blade of a hoe, which limits clogging. If the soil is too dry it can become very hard, which can be challenging as well. When using overhead irrigation or after a rain I like to wait at least a day or two for the soil to dry out before going into the field for hoeing (soil type and saturation plays a role in the timing here). Conversely, I try not to hoe just before an irrigation for fear that weeds will re-root and the loose soil will become compacted. Most of the time it’s hard to work around the rain and you just have to make things work, but if you have a choice, hoe when the soil is dry and when it’s going to stay dry for at least a day or two.
There are three basic ways to kill weeds with a hoe: slicing them off, pulling or dragging them out of the soil, and burying them. Slicing the weeds off is usually the goal with a sharp blade but frequently that turns into pulling or dragging the roots out. Even when the hoe is dead sharp, it will clog occasionally if the weeds are thick or the soil conditions are sticky. I wear thin gloves when hoeing and frequently clear my blade with my fingers when it starts to clog. Rakes also pull and drag weeds out, leaving them on the surface to desiccate. With both the rake and a hoe, especially when working in more mature crops, you can usually concentrate on slicing or dragging weeds between rows, while simultaneously hilling a bit of soil in the row to bury weeds. Especially on tightly spaced crops this is much faster, and safer than trying to get the blade of the the hoe close into the row. I’ve found that most blades, when moved with any speed at all, will push soil over about 1-2 inches on either side of the blade. This means that a pass with a 5” wide hoe, actually effects a 7-9” swath of soil. The slower you move the blade the less this happens, although the chunkier and wetter the soil the more it happens. So, when I’m selecting a blade width for 12” row centers, I usually look for something about 6” wide for tender crops and small seedlings. For larger crops that will take some hilling I might go up to a 9” wide blade. There are many crops that benefit from some hilling in the row as well, ranging from roots like carrots and beets, to alliums, to the obvious ones like potatoes. With a straight thin blade, you can make the blade effectively narrower by pulling it at a slight angle. This also helps the blade shed material that would otherwise clog it.
I debate a bit about working the entire bed surface at once as I slowly walk down a bed, or concentrating on quickly moving down a single line at a time, walking up and down the bed multiple times. In general I find it fastest to work single lines, which doesn’t require me to constantly reposition the hoe on the bed. I also find I’m less likely to miss sections with this slightly more methodical pattern. In widely spaced crops I frequently break that pattern to wind between plants at the same time as I move down the row.
Working with weeds
Some crops, once they are established, can tolerate a relatively high rate of weed competition and still produce profitable crops. I’ve had this experience in crops like sweet corn and winter squash. For these crops, I think about the crop that will follow in the next season to justify extra hoeing. Keeping weeds from going to seed and perennial weeds from putting energy into their roots by limiting top growth pays off in subsequent seasons. In addition, the easiest time to kill the weeds is when they’re small, so investing extra labor early in the season can reduce your labor later in the season as well as in following seasons. The one other advantage to keeping weed pressure low that I’ve found is that it speeds harvest because the crop is easier to see, and easier to get to. The disadvantage is that it always feels expensive and it’s easy to second guess whether it is money well spent.
As much as I love the look of a clean field and the mulching effect of cultivating soil, I recognize that there is also a price that the soil pays. Constant cultivation and tillage breaks down organic matter and soil structure over time. I’ve heard of farmers who work very successfully with weeds as a part of their cropping system and I am alway looking for more information on how these systems work so that I can reduce my energy inputs and the damage I’m doing to the soil. In my thinking, weeds are incredible scavengers, helping to bring nutrients to the surface and to keep them cycling, frequently providing habitat for beneficials, and they help to hold soil against wind and water erosion. For these reasons I am not weed phobic, I just try to pay attention to the weeds I have, what they are telling me, and whether they are benefitting my long-term goals in the times and places that I see them, or if I need to limit their growth.
In the fall and winter I rarely cultivate out weeds, and I appreciate mats of chickweed that fill in where I haven’t been able to seed a good cover crop. Chickweed tends to cultivate out easily when I don’t want it, and it only germinates in cool weather so it’s not a problem for the majority of my planting season. It also grows relatively slowly and low so it usually won’t smother cash crops quickly, like many of the summer weeds we have will.
I also use mowing, instead of cultivating, in some situations in the summer where I want to reduce tillage, but I don’t want a cover crop or weeds to go to seed. This creates a type of sod, and sod is a great way to build organic matter and to keep nutrients cycling close to the surface. Mowing does create some compaction in the soil because the tractor has to drive over, but it usually takes less horsepower than tillage, and doesn’t cause the other types of damage that tillage does. In places where I want to maintain good pathways I use weeds or cover crops to create a sod which creates mowing work, but eliminates cultivating work in those spots. This works well in high traffic harvest crops like summer squash and I like it for separating melon varieties as well.
Looking past the weeds
I just finished hoeing a few rows of carrots and beets with my good friend Michael Ableman and a few of his interns during which I remembered a few other reasons I like cultivating. Beyond the goal of eliminating weeds, spending a little time at the end of a hoe (or even cultivating on a tractor) provides an excellent opportunity to look briefly at every plant in the field and to “feel” what is happening in the soil as you watch the surface interact with the tool. Cultivating can also be considered field scouting for moisture problems, pest and disease issues, variety evaluation and assessing other needs like trellising or even harvest timing. When I’m hoeing I have time to think about the crop and what it needs, weigh options, see the whole field, all while doing something productive with my hands. Most simply, it helps me understand the plants by spending more time with them at times in their growth cycle between the times that I am forced to be there at planting and then again at harvest.
Josh Volk farms on the edge of Portland, Oregon, and consults with farmers around the country on their farming systems. He can be reached at www.slowhandfarm.com.