Benefits of No-Dig Gardening - Why Do No-Dig Gardening?

I've noticed that there is some discussion on planting in a no dig garden, but perhaps some discussion on the benefits of no-dig gardening would help get people on the band-wagon. In Edible Paradise by Vera Greutink, I think she lists some awesome reasons to do no-dig!

Vera Greutink wrote:
1. No Propagating Perennial Weeds
2. Less Weeds Germinating
3. Preventing Back Injuries
4. Protecting Soil Life
5. Reducing CO2 Emissions
6. Less Watering

What are some other benefits of no-dig gardening? Why would anyone want to do no-dig gardening?

Preventing erosion particularly on sloped ground.

Natural soil tilth, where the upper duff layer is not mixed in the lower soil.

CO2 emissions could be from two sources, fuel burned by tilling machines, and gasification of exposed soil.

Perennials can be grown adjacent to or amongst annuals without them having to be moved or damaged each time.

Very low start-up cost, since there's no motor to start up.

My no dig garden got full of weeds, even grass. In the second season I still had desirable plants growing, but the weeds took most of the space.

I think you need to mulch heavily to reduce weeds in any kind of garden, while growing your seeds somewhere else until they’re quite large seedlings, then transplant into the mulch and hope the slugs and snails don’t kill them.

Morag Gamble recently posted a youtube video on builiding soil health and humus layer and how it positively influences rising carbon levels in the atmosphere.    Worth a watch.  Masterclass #18 if I remember right.

If you are cultivating annuals that more readily adapt to no-dig conditions, they will out-compete undesirables that require soil disruption to propagate.

Not digging or inverting the soil means that only the part of the soil's seed bank that is in the top strata of soil will have the chance to germinate, meaning that as you continue to garden in this fashion, your influence on self-seeded selection will have the chance to overtake the wild seed bank, meaning fewer undesirable species going to seed on your property over time, and no herbicides and little weeding, just before the stragglers go to seed.

I think that the advent of actively oxygenated compost extracts and fungal slurries can make bolstering the soil life without digging much more likely. I think that there are absolutely some situations that might require digging aside from earthworks for hydrological control, but I think it would most likely be in instances where there's a desperate need to add organic matter into the active strata of the dirt to give the bacteria, fungi, and hard-working little soil creatures something to eat while they transform that dirt into soil. If the soil life is already bumping there should be little need for such soil disruption, which makes no-dig a winner for all the effort-saving and soil-life-friendly reasons listed above.

-CK

I actually prefer minimal dig. I like to dig small holes and fill them with compost or manure if something hungry is being planted.

For weed control I like it the Dutch hoe. It disturbs only the top half inch or so of soil, so you have some of the benefit of tilling, without inverting the soil.

One thing I will probably have to make for myself, is a quite robust and wide Dutch hoe that can be pulled by a water buffalo. The current practice is to use a moldboard plow followed by a tooth harrow, pulled by the same animal. This is something we'd want to accomplish in the morning, on a day when it gets blistering hot, without rain. Then rake the cut off weeds, into piles that will become mulch, and seed the field.

On sloped land I don't imagine doing much to the weeds between plantings, since they help prevent erosion. So it might be best to just mow them short and grow things that compete well with a weedy understory.
........
Chris mentioned very difficult conditions, where it might be necessary to dig. Really difficult conditions can be seized upon as an opportunity for domesticated plants to win the battle with weeds. Some plants like squash, can grow outward from a very rich pocket of soil, and form a living mulch that starves other plants of light. If these squash are watered only in their fertile hole, a large expanse of marginal land can be covered. A similar thing can be done with corn circles, or banana circles or almost any row crop , where you dig a trench and only enrich, water  and till a small area under the desirable plants. Worms and other agents of decay will eventually spread fertility around.

I had a garden on the edge of a mountain in British Columbia, that had very dense rock powder mixed with clay. The trench method was used, which gave good results. Lots of organic matter was used to mulch these rows. Within about 5 years, all of the soil was workable and none of it had to be worked up very much.

We moved from black-tarp mulch, rototilled gardening to a no dig garden once we were living in our homestead ft instead of weekend warrioring from the city. Since the change ive noticed we have many MANY more earthworms and also the benefit of self seeding plants like calendula, dill, sunflowers, and even tomatos. We put out a call on our local community facebook page for spoiled hay and had a lot of responses. So we've been slowly emptying a mow at a nearby farm and we apply this hay liberally to the garden beds. I heard many naysayers warn about weeds from the hay and perhaps we've had a few,  but the soil is so loose and lovely they pull fast and easily. Or, a la Ruth Stout, you can just smother the weeds with more hay. We plant densely and add manure at planting time. Every year something does better,  and something does worse,  but we still have a lot more veg than we did in the past. The irony is we bought a rototiller just before switching methods but will still use it for breaking new ground. Happy planting!!

Dale, I love the spot improvement method. As you have detailed, it's a flexible idea that maximises output from a singular focus. This doesn't apply to you, but if one were to have an air-conditioner, something producing condensate, that condensate might evapourate in under a minute if it is left to drip on a tile roof or onto concrete. But give that tiny drip somewhere to land where it doesn't immediately evaporate, with a little life and fertility, and it will start the process on it's own. Give it some help, and it's the start of soil generation in the area.

Jess, I am glad to hear of your ramping-up. I think that rather than weeds, my concern with imported hay would be persistent pesticides and herbicides. I hope you don't have any unpleasant surprises when you go to germinate tender greens or some such.

Hopefully, weeds in your hay are all you have to worry about, though. The method you describe seems sound.

Don't despair of your rototiller, incidentally. If you haven't perused the threads yet, Dr. Redhawk's Epic Soil Series has enough soil info to cause a brain hemmorhage if you try to take it in all at once. He covers how to make and use compost extracts to best effect to get the soil microorganisms where you want them, talks about bacterial and fungal interactions in the soil, about clays, amendments, and about organic matter.

He also mentions two things that may be of interest to you. The first is when it is preferable to till, and how to do so to achieve the goal of jumpstarting healthy soil from degraded dirt. The second is a compost extract injector, essentially a spike that you drive into the soil that connects to a hose that you use with compost extract in what I think is a venturi valve setup to inject compost extract into the soil strata without inverting or even really disturbing it.

But your gardens look lovely. I wish you every success.

-CK

We do a layering method with garden beds. Adding compost, mulch and hay in that order to beds at rest. Eventually we will utilize more cover crops. Right now we are adjusting to our growing conditions.

I prefer the no dig method for established beds. Not wanting to disturb the our soil building efforts by bring subsurface parent material of soil layers to the surface. Keep the good soil stuff on top, rhizosphere. I think it's called.

We are terracing a hillside so we are disturbing lots of soil now. Adding in lots of organic material. When these beds are good and growing we shall halt our digging.

Dale,

I really like your thoughts on the fertile holes and Dutch hoe.  I am transitioning to a mushroom compost bed system, but while the chips are rotting down and microorganisms still colonizing, I do dig a hole, add in some bagged manure and plant.  Hopefully, next year I will have a 2 year old mushroom bed that will be sufficiently rotted that I can direct sow.

I have also used the Dutch hoe. I got mine from Proehoe.com and rougehoe.com.  These are made from old disk blades that are recycled and cut into a high quality hoe.  I have several of their hoes and they are very heavy duty.  They also come razor sharp.  I personally prefer the fiberglass handles, but they come with hardwood handles as well.

Really good insights,

Eric

Chris Kott wrote:Jess, I am glad to hear of your ramping-up. I think that rather than weeds, my concern with imported hay would be persistent pesticides and herbicides. I hope you don't have any unpleasant surprises when you go to germinate tender greens or some such.

Indeed, we're taking a risk there. We're trying to stay organic and in the vegetative sense of the word since gleaning means we're susceptible to other people's activities. This might change over time.

Chris Kott wrote:Don't despair of your rototiller, incidentally. If you haven't perused the threads yet, Dr. Redhawk's Epic Soil Series has enough soil info to cause a brain hemmorhage if you try to take it in all at once. <snip>

But your gardens look lovely. I wish you every success.

-CK

Thanks Chris. Great tip! There's so much information on these forums! And it's encouraging to be part of a community of positive action instead of negative reaction.
Stay happy!
-jp

I was against tilling. As mentioned it destroys the natural base, disturbs the undergrowth. Destroys the air pockets for everythig to thrive. BUT I discovered that the rototiller has its place. I moved onto land that was pure sand but never touched and the ground was rock hard. That first year we had no water. I placed strips of hay on the ground and in hopes the winter snow would be enough. It was not. I tried making holes into it the second year to grow and what a mess and a lot of work. That fall we got a rototiller and tilled in the hay and soften the ground.

After that first go with the rototiller that land was much more workable. A few years passed and in my case cause the ground literally was all sand it was not enough to hold water or provide the nutrients I wanted. The ex finally made beds for me. I dug a foot below, added wood mulch to hold water.and soaked the beds. Then added alfalfa hay, compost and the sandy soil I dug up. I added lots of organic nutrients and a very thick layer of alfalfa hay mulch on top. By the second year, there was very little to do. Each bed consisted of companion plants. Some annuals some perennials. There should not be a need for amendments for awhile. A thick layer of hay mulch on top means a few things. Keep the soil from drying out to fast. Adds nutrients as it breaks down. Weeding is so easy. The weeds just pull out and no tools required. I spent maybe a half-hour every summer weeding? The only true weeds were vines. Almost every so-called weed I harvested for food.

I would trim plants once they went to seed and only left those that I wanted to self-seed. Self-seed was not letting the seeds drop on their own. I would watch carefully and when the seeds were ready I would gather them for myself as extras and then drop some of them at the base of the plant. This way the wind seldom got them. Also, self-seeding is amazing because they always grow faster than whenever you think you need to sow seeds. There are so many perennial plants that grow so well in Canada. From herbs, fruit, and vegetables. I did not need to seed much on my own and I learned I really did not need to transplant either. Plants are stronger and more productive when planted right in the ground from seed.

I wwoofed in Germany once and built no dig terraces as a part of that experience. I wouldn't trust it in a place with bad flooding though

We use both no dig/till and we till, mainly because we don't yet have enough materials to fully go no till on all the areas on our 5 acre property.  I prefer no till.  It mimics nature, which does it best.  There're SOOOO many reasons to grow no till.  No till is AWESOME.  Here's a tip for those wandering about what to do for weeds that pop up though their mulch.  I like to use cardboard (free from most area stores) or newspaper if I have it.  I cover the weeds with it and add more mulch on top of the cardboard/newspaper to hold it down.  The weeds have no chance at coming back in that spot... at least not that season.  LOVE no till.  :)

T.J. Stewart wrote:We use both no dig/till and we till, mainly because we don't yet have enough materials to fully go no till on all the areas on our 5 acre property.  I prefer no till.  It mimics nature, which does it best.  There're SOOOO many reasons to grow no till.  No till is AWESOME.  Here's a tip for those wandering about what to do for weeds that pop up though their mulch.  I like to use cardboard (free from most area stores) or newspaper if I have it.  I cover the weeds with it and add more mulch on top of the cardboard/newspaper to hold it down.  The weeds have no chance at coming back in that spot... at least not that season.  LOVE no till.  :)

Just a point of interest on the paper and cardboard. I posted about my first year and how I had to eventually till. Here is what was not shared. That first year I laid down paper and cardboard then the hay, about 4 inches thick or more. The winter snow, which was over 2 feet during the winter months, was not enough moisture come spring to dampen, break down the paper and cardboard. Yes, you can build if available, a foot high of mulch, compost etc to grow in ( like the eden method) but the best results even if you do that is when you lay down paper/cardboard is too soak it completely. Even though I had about 4 inches or so of hay on top, yet the paper and cardboard was so dry come spring, when I was ready to plant, weeds were still coming up from everywhere. Pushing the cardboard up, finding a hole to grow through, etc. If the paper is soaked and kept soaked it will actually break down and suppress the weeds in the interim. It will also become part of the soil eventually. If you do plant later it will be easy to make a hole and plant in it.  Since TJ had success maybe it was the type of mulch that was used? finer and hold moisture better?  I used hay and did not keep the cardboard saturated/damp to suppress. For me, all I know is I really had to soak the paper and keep it soaked to be successful to suppress weeds. Anyway, just something to think about if you use paper and cardboard.

Oh for a question that might come up. I did the best I could to over lap so that did not provide cracks for weeds. When everything was done in the fall there was no green, earth, soil to be seen.

@Pamela It could also have something to do with the differences climate and the amount of rain that our respective areas get in the fall and spring.  Never the less, good idea to bring that up since we don't all live in the same climate/zone.  

As a gardener, I wish to build organic matter in my soil.   The difference between dirt and soil is organic matter.  And the more organic matter there is, the richer the soil life which makes for happier growies.   As it turns out - it is also sequestering more carbon!  As well as making the soil so it can hold more nutrients and water.  


every time you till the soil, you lose 30% of your organic matter


Or sure, your growies LOVE it the first year.   Since all of that life was crushed, the plants can consume the nutrients of all those dead bodies.   But, of course, after a few years, the soil turns into a cement like dirt.  

Of course, if you are starting with cement like dirt and you wish to till in organic matter, that makes sense.

Yes- soil life prefers no-till. And I proved it again to myself recently...

We've been gardening no-till for 15 years now, in our annual vegetable garden. Every fall, without turning, only lifting and cracking the soil column, I lightly broadfork the beds that will be sown with early spring crops and cover with compost and straw. In the spring, I move aside the straw to plant, seeds or transplants. The rest of the beds get cover crops for the winter, and when beds are workable, I dig holes for transplants, and weed the cover crop as I go. Beds that will be seeded get a a chop and drop weeding in the fall, covered with straw, and then raked out in the spring or early summer when soil temps warrant seeding.  The paths all get edged where they meet the lawn. On the paths I put down recycled un-bleached paper I buy by the roll from the local newspaper (end-of-roll from the printing press, no ink) and cover thickly with chips or straw, whichever I got free from craigslist, etc. I have to do some weeding through the summer, but not too bad, and usually it happens as I finish harvesting one bed and prepare/plant the next crop. Over the years, the number of unwanted weed speouts have dramatically declined. Our soil is rich and lovely, or WAS, until...

We rented our house for five years to go live and travel on our sailboat. Our renters were students, and not interested in gardening. Because I am near 60 and didn't want to go through a lot of weeding and soil improvement when I moved back in, I covered the beds with water permeable landscape fabric and a layer of bark (couldn't find anything better for free at the time.) Fast forward five years, we moved back home and I uncovered my beds. Dead soil. Very few insects, almost no worms. Annual garden was terrible the first summer. Now, nearly two years later of composting in place, cover crops and mulching, spraying with aerated compost tea, I think the beds might have enough nutrients and soil life to grow a good crop next year. Lesson re-learned: soil fabrics are bad for soil life. I and the earth would have been better served by letting my beds go to grass while I was gone, and starting over again with layering materials to create "new" beds again.

With the exception of needing to till in nutrients in hardpan, sand and the like, tilling also degrades soil life. I think the initial satisfaction of seeing all that rich brown plant-free soil stretching out behind the rototiller sometimes may create an illusion of fertility, and less work, when in reality it might be causing more work in terms of inputs needed down the line. At least, in my case, this proved to be true. Note: I am not a market gardenr. Our garden provides most of the vegetables needed for my husband and I for about 6 months of the year.

Dave Burton wrote:I've noticed that there is some discussion on planting in a no dig garden, but perhaps some discussion on the benefits of no-dig gardening would help get people on the band-wagon. In Edible Paradise by Vera Greutink, I think she lists some awesome reasons to do no-dig!

Vera Greutink wrote:
1. No Propagating Perennial Weeds
2. Less Weeds Germinating
3. Preventing Back Injuries
4. Protecting Soil Life
5. Reducing CO2 Emissions
6. Less Watering

What are some other benefits of no-dig gardening? Why would anyone want to do no-dig gardening?

The main benefits of No-Till gardening (aka no dig gardening) are:
The soil microbiome is undisturbed and thus will flourish since UVA,B and C won't be able to bake the organisms, this allows the soil to be as fertile as is possible without any un-natural amendments.
Part of this process is to retain at least 3" of mulch covering the soil to keep the light rays out and moisture in.
Since we aren't disturbing our microorganisms they and the macroorganisms will pull in and digest the organic matter we spread on the surface as mulch, this brings carbon and other nutrients down into the soil where it becomes part of the soil food web.

With the healthy microbiome organisms thriving, the only amendments that should be needed come from compost and mulch, both used as top dressing of the soil.
Plant spacing can be closer because of the thriving microbiome, allowing for more production in the same space dimensions.
Worms (macro biome of the soil) and the other macroscopic organisms can go about their business without the interruption of being cut to ribbons by tilling actions.

The only time to use tillage would be to break up dirt (lifeless earth) and add in large amounts of organic material, when we do this we need to add the microorganisms back so we water with aerated compost teas until the earth shows it is once again soil.
I call this One time tilling in most of my posts where I mention tilling or tillage.
Broad forking is far and away superior to any other type of soil disturbance for loosening compaction and working in amendments.

Redhawk

We started with horrific clay. The only soil help was pesticides.  Then we took out the grass and added leaves and wood chips every year. We have good soil now, 10 years later.  It started to get good about after 3 yeaers.  Now we have enough food forest growth that we can trim the excess  wood and burn it into biochar, which will help drainage and as housing for the required microbes.  We'll probably always keep adding wood chips, as we remove matter in the form of fruit, vegetables, herbs, and vegetables every year.  One good sign is that we get a wide variety of wild mushrooms every year, so there is a good mycelial network underneath, which is another good reason to not till.

John S
PDX OR

You guys have mentioned all the good things about doing a no-dig/no-till garden.

I couldn't agree more.

One of the things that I have found wonderful about the method is that it has continually challenged me to see the beauty in the chaos. I was brought up believing in the tidy lines of dark soil waiting to get planted, like the last post was talking about. But with our declining water in the northwest and my want to capture more nutrients and water in the soil, I've been changing over to no-dig in several of our gardens, including our raised bed kitchen gardens up by the house.

In the fall and winter, in the spots where nothing is growing and I've harvested what I wanted the area just looks...messy. Unkept. Straw piled a foot high with only the walkways in the staple garden to disseminate where the beds are. From the house, it looks like sea of beige. And with the rain and the constant cloudiness (which I LOVE, don't get me wrong) the area looks bedraggled. I have to keep reminding myself that the soil underneath the straw is teeming with life and to focus on what the garden looks like the 3rd week in July. Sometimes when people come over they kind of look at it and wince. Not the gardeners, though. Straight up they look at me and say "Dude. Nice mulch." Because, you know, they get me.

No till has taught me the value of "weeds". The value of challenging all of my long held assumptions. It's causing me to turn my habits and old stories on their head and make up new ones. When the garden is going insane full tilt come July, it also looks a bit more untidy then it did when I had weeded rows of dark earth with tidy crops growing in them. I think I like how it keeps me interested and focused on building the good in the soil, unlike an old paradigm I had when I first started years ago, which was more like what can I get out of this soil.

Anyways, I like stuff that keeps me learning. And no-dig keeps me experimenting and figuring stuff out.

No-dig seems to save time.

It seems based on dropping a blanket of mulch on last year’s mulch. That’s a faster way to weed and prepare new beds. When weeds do come up they’re less numerous and easy to chop or pull out, again saving time.

I just heavily mulched with chips for the first time a few weeks ago. They keep falling back onto the seedlings I plant in deep gaps. This leads me to plant more sparsely, which will result in larger more productive plants. This again saves time with fewer plants to plant in and look after but enjoying high yields.

One idea for planting in deep mulch areas,  depending on your feelings on reusing plastic..   I cut large plant pots into a few rings a couple inches tall, and use it around small plants/ seedings to keep the mulch back until they are a bit bigger (and so I don't forget and step on them) .  

Yeah I’ve tried with plastic milk bottles in the past but they were unstable or slugs made a home in them. I’m hoping my mulch breaks down to humus eventually and then it’ll all get easier. As it’s a long-term project it’ll happen eventually.

Edited to answer the OP, benefits of no dig

The biggest benefit to me is that the soil life is better.  I am a firm advocate of soil building.  Build great soil, so I am always "feeding", taking care of the soil, not the plants per se.  If the soil is in balance and great, the plants will do great.  SO, not messing with the soil by not digging or tilling means happier soil ecology, good microorganisms, etc....

I can see the difference very distictly on how my soil looks compared to a friend who started out with similar soil, and he plows it, so he is pretty much light colored, fine sand at this point.  My soil is darker and full of life, even though of course the base of my soil is like his and it is sandy soil.  Mine is alive.  The results of the plants we grow and the yields show this too,  I get crazy productive squash and tomatoes and ......  

Is it less work ?  Well,  carrying mulch once or twice a year is no joke, but I then do not need to weed, so it evens out, and hte soil is alive and happy and full of organic matter

Are any of you growing cover crops in your garden in late fall?
IF SO, how is that working out in the Spring and how do you handle that growth to get your garden planted?
I know farmers till it in, but, do you just scythe down the cover crop and leave it lay as mulch, or what?

What are the cover crops grown?

I'm always getting plants in the wrong places, excess growth on something or needing to limit or remove something. I only have a suburban garden, not a real farm.  I just use a version of chop and drop that I call chop and rotate. I move the plant material to beneath a different plant area to which it is not related, to limit disease and overconcentration of one plant instead of diversity.  I don't till it in.  I just leave it on the surface and as it rots, the worms know when to bring it down.  This has been demonstrated, as has mulching, to be quite effective by research such as by Linda Chalker-Scott.

John S
PDX OR

I use a no dig method but with a couple of very important twists that seem to do wonders for my garden. First when I create new space, raised bed, I do turn soil because where I live near Atlanta, GA our soil is pure gray clay with removed top soil which requires a lot of soil amendment. When I do turn the soil I amend it with composted leaves, pickled weeds that I pull by hand around my garden. Pickled weeds are brined in a water solution mixed with Epsom Salt. Let it sit for 3 days and then the stinky layer goes into the deep layer of the raised that instantly eliminates the odor, activates the flora in the soil. It's followed by native soil mixed in with sand and layer of ready made compost. The top layer is composted wood chips. I prefer aromatic cedar mulch that keeps pests away. For 2-3 years the bed is a high yield producing bed and I have even managed to grow nightshades plants in the same bed for several years which anyone who grows food in the South knows given our high humidity nightshades quickly attract fungal issues that quickly destroy crops. So from the initial soil amendment, I don't disturb the soil again. Annual amendment of a layer mulched tree leaves, mowed pesticide free grass and compost for next planting continues to build the soil fertility.

Another twist. After several years of no digging/turning soil, you do run a risk of allowing fungal spores, pests taking hold in your raised bed. That's when I deploy the ancient trick of making terra preta, creating bio char on site. A lot of people make bio char in a chimney. I prefer to create bio char in the same raised bed that I grow food. Piling up dry branches I make fire and then cover up with soil/sand to cut down the oxygen level. Next day the bed is ready again for the next 2-3 years without a danger of fungal attacks on my plants. The bio char cooked on the site quickly restores the vitality of the micro flora in the bed and now you have additional mineral elements increasing your bed fertility. Amazon has been functioning like this for thousands of years with great results so why not to utilize the same concept.

Jesse Glessner wrote:Are any of you growing cover crops in your garden in late fall?
IF SO, how is that working out in the Spring and how do you handle that growth to get your garden planted?
I know farmers till it in, but, do you just scythe down the cover crop and leave it lay as mulch, or what?

What are the cover crops grown?

Starting last fall, I've tried three so far.

Last year I fall planted (smallish) areas in winter rye and in oats. They looked pretty similar while growing, but winter killed the oats, so by spring, there was just some broken down oat straw sitting on the soil. The rye plants quickly resumed growth, and did really well in one garden; a little less in another. In mid spring, I stopped their growth (or tried, anyway). Since I do no-till, in one bed I tried to cut with heavy duty scissors at the base of each plant. Way too hard, and the rye kept growing from the roots. In another bed, I gently pulled each plant (easy) and laid them all down in overlapping fashion, so the soil was basically covered by this rye straw and rye root combo. Also the roots keep managing to re-root, so I have to give them a little tug. In this way, a number of the plants actually managed to set seed--they wanted to so badly! Next time I do this, I plan to have a scythe or sickle and cut below the crown, but leave the roots in the ground.

I've moved this layer of rye "straw" aside to make room to plant tomatoes, and so far so good. I think this fall I'll put in a whole lot more winter rye and oats, as well.

My third cover crop I'm testing out right now is buckwheat. Easy to seed, grows quickly and well. I seeded it in the mid to late spring. None is ready to cut down yet, so we'll se how that goes. For now, it's keeping soil covered, so I'm happy with that.

Tim Kivi wrote:My no dig garden got full of weeds, even grass. In the second season I still had desirable plants growing, but the weeds took most of the space.

Did you weed regurarly? From the no-dig market gardening videos i have seen it seems that you have to keep it weed free,
because seeds blow in, and if you don't pull them out asap they go to seed and cause even more trouble.