There seems to be a lot of concern over the size of the hole that an upright weeding tool makes when it pulls the weed. Without overstating the obvious, when an object is removed from the ground a hole is created, the larger the object the larger the hole. We can't do much about that.
A Dandelion's taproot can be several inches long if left unattended. It is quite difficult and very unlikely that you will ever remove all of the taproot by pulling a taproot up with mechanical tines. When using an upright weeding tool it requires the operator to drive the tines into the ground and then free the root by twisting it to break it free, it goes without saying that the soil needs to be soft. The primary reason that the soil should be soft is to drive the tines fully into the soil. The second reason and the most important is the ground needs to be softer than the taproot.
Pictured below is a taproot of an established Dandelion. This was not extracted by a typical upright weeding tool, instead I used high-pressure water forced through a small orifice along the side of the taproot.
The only reason I was able to remove this taproot in one piece is because the jet of water broke the root free from the surrounding soil. You might say I teased it out of the ground much like you would pull a worm from the ground. This is an extremely effective method for removing Dandelions but it is not very practical. It took about 3 minutes to pull just one weed.
Even when I extracted this weed I created a hole, most of it filled back in as the water drained. The bottom line is you are going to create a hole, how big a hole will be determined by the tool or the method you use. I personally do not care that I leave a hole. My yard looks fantastic even after I spend hours removing weeds. The holes are temporary and necessary and they are a vital step toward making your lawn healthy. It is called aeration and it is a very good thing. This post is not to discuss the benefits of aeration it is to compare hole size between different upright weeding devices.
I did a test using the Fiskars, Weed Zinger and Gardena to see for myself the size of hole these weeding tools leave behind. I personally never paid much attention to the size of the hole because I have always used the Weed Zinger. When I use the Weed Zinger, even after a couple hours of weeding, you can barely tell that there are holes everywhere. One reason is because I do not "scalp" my lawn, I keep it higher to crowd out the weeds and I always use mulching blades. This prevents the lawn from burning and I am reintroducing nutrients back into the soil. These holes vanish after 2-3 days anyway or after a good rain. The rain washes loose soil into the holes which promotes root growth.
I wanted to see for myself what all the fuss was about so I did a test of these 3 upright weeding tools and I must say that I was surprised. The images below are the results of my test.
Fiskars: By far the most aggressive tool I have ever used. It's tines are large and powerful and it displaces a lot of dirt. If you are reluctant to create a hole and care what your lawn looks like then do not use this tool. The hole depth was 3" and the diameter was 2". Keep in mind this was done on a section of the lawn with no weeds. If I had conducted this test on a dandelion the hole would be much larger because the taproot and tendrils of the weed would pull up the surrounding soil that is compacted around it.
The video below shows what the Fiskars does to an area with several pulls in a concentrated area. The surrounding area was ragged and torn as if a small fire cracker went off.
Gardena: The gardena has the longest tines of any weeding tool and it made a very deep hole, about 4". The diameter of the hole was a little more than an 1". It was an incredibly clean hole but very deep. The primary issue I have with this tool is that the ground has to be incredibly soft and there is no foot pedal to drive the tines in. It is very challenging to drive this tool into the ground and it is difficult to twist it once it is in the ground, even in soft ground.
Weed Zinger: The hole made by the Weed Zinger was small and conical shaped. It was 1.75" deep and slightly less than an 1" in diameter.
In summary, all of the weeding tools made holes. The Fiskars made the messiest, The Gardena made the deepest and the Weed Zinger made the smallest. None of these devices would have pulled all of the taproot out unless it was only a couple inches deep.
The Fiskars is the strongest upright weeding tool but it is better suited for saplings and it will make a nasty hole. I often use the Fiskars for Crabgrass and small saplings. The Weed Zinger is by far the best for Dandelions especially if you do not want to leave behind a large hole.