How To Edge A Flower Bed / Garden With A Shovel

All homeowners like to keep their yards looking their best, and having a well-defined edge or border between your lawn and flower bed can greatly improve the appearance or curb appeal of your yard. Trying to maintain a border between mulched areas and grass can be frustrating. There are several options to do this, but making a small trench between them is about the most effective, cheap (free), and trouble-free method I’ve found. In this guide I will show you exactly how to do it, why it works, and give you and idea how much effort it will take on your part.

Tools

For tools, you really only need a garden spade (flat shovel) at a minimum. But a wheelbarrow, small hoe, sturdy rake and/or an edger can greatly help as well. But 95% of the work will be done with a garden spade.

Process

Our goal is to create a small trench that is about 2-4″ wide by 3″ deep, with the mulch side sloping to the bottom, and the grass side to be a nice vertical cut. Since the rhizomes (runners) of turf grass generally don’t go deeper than 2″, this will make an effective barrier of air. (Click here for or a more detailed explanation of rhizomes) You see, rhizomes will go wherever there is moist soil, and the soil under mulch is no exception. But, if they encounter air, they will stop. They will not grow out the side of the trench, they will be effectively stopped from spreading into the flower bed.

Start with moist soil

Before we get started, it is important that we are dealing with moist soil. Moist soil is easier to dig, and will save you much effort as well as offering better control. So, do this after a rain or at least give it a thorough soaking before you get started. Also, the best time to do this job in early Spring when the soil is moist. Early Spring also offers an advantage in that the roots of the grass are generally a bit thinner.

Layout your edge

If your garden bed isn’t yet defined, now would be a good time to do that. Use steaks with rope or string to help guide your profile. Now, don’t over think this step, as it is easy to remove or add soil to adjust the profile later in the season. We aren’t pouring concrete, we are making a small trench.

Cut the vertical wall

I like to do this job in two passes. The first one is a straight vertical cut several inches deep into the grass. To do this, place your shovel straight up and down, parallel to the path you wish to take. Then, place your foot on it and press into the soil.

You will need to plan on going roughly 4″ deep. But don’t stress if you are a bit deeper or shallower than this – it won’t matter. Continue making this cut until your profile is finished.

Partition the wall

Ok, so we are going to be taking out chunks of sod/soil, and it can be quite labor intensive to try to do it in large length chunks. So, once you have finished your vertical wall, we are going to make some partitions. This way, when we do the next step we can quickly remove the sod chunks as we dig them.

But once you’ve finished the vertical wall profile, we can turn around and partition the sod we will remove. So, we will make vertical cuts perpendicular to the vertical wall we just made. The distance between these cuts will determine the width of sod chunks you remove. I recommend you make these chunks to be the same width as your shovel, or at most 2X your shovel width. This way you will be able to flip/dig them easily in the next step.

Cut the slope

Next we are going to dig down at an angle towards the base of the vertical wall we just cut. This angle serves two purposes. First, it can’t collapse! It is a low-angle slope that will allow some mulch to spill down to our vertical wall, but it’s slope allows us some forgiveness. It also means we have a larger area to work with, which makes it easy to do maintenance or remove more ‘wall’ in future years if we like.

Before you get started, position your wheel barrow near you if you have one. Then you will be able to just flip the sod into it, saving a future step of picking it up off the ground and placing it in.

Start your cut in the garden/flower bed, about six inches from where you want your profile (the vertical wall). What I normally do is to angle my shovel about 30-45 degrees down from horizontal, and dig towards the vertical wall. A 30 degree angle started 6″ away from the vertical wall will result in the final depth of the wall being 3″. You can adjust the angle more or less, or the distance based on preference.

But dig towards the wall, and flip out the grass as you go. Continue doing this until the edge is finished.

Alternate cutting method

For another method, one that is arguable easier on the back, we will cut parallel to the profile. Now we will still make the first cut perpendicular to the vertical wall, but after that we will get down on our knees and go parallel to our profile. This method is best used when you have plenty of space.

To do this method, after I make the first cut at the start of the edge perpendicular to the profile, I will get on my knees, and use the shovel to cut in-line with the trench. This is way easier to do, although your legs will get a bit messy. But hold the shovel at an angle, and cut into the sections, flipping them into your wheelbarrow as you go. Do this following the entire profile.

Smooth out the trench

This step is optional, but it doesn’t take much time. Take a handheld hoe / cultivator and smooth or even-out the bottom of the trench. This will keep it looking tidy.

Mulch

Depending on the age/maturity of your flowerbed, you may need to reapply mulch to the area you have just excavated. Go ahead and do so, using a rake to keep it even. Just make sure you don’t fill your trench with mulch, lest the grass rhizomes may return!

Video guide

Here is a short video we released showing the process in detail. I hope you enjoy it!

Maintenance of a garden edge

For maintenance, we are going to have several types when it comes to the edging/trench we built. First will be trimming, and the second will be keeping the edge crisp.

Trimming

When it comes to trimming the lawn-side of the trench, you can do this with a string-trimmer. Just make sure you know which way it spins, and only trim it so that the clippings fly into the lawn – not the flower bed. I also have a hack-method that renders this job moot. It works with my Honda push-mower, but may not work with others. But I find that I can just drop one wheel in the flowerbed, keeping the other safely in the lawn and push mow the edge. The base frame of the mower runs along the corner of the lawn and keeps it all mowed up nicely. You just need to make sure the blade doesn’t get into the soil.

Annual maintenance

For keeping a crisp edge, just inspect the state of the trench each Spring when the grass begins to green up. You may find that the ‘wall’ has collapsed in places, or that you feel you need to straighten out the profile. Since you already have a trench built, you can simply make fine adjustments with your flat-shovel. Or, if it has been a few years and you just want to freshen it up, simply shave off 1/2″ to expand the trench.

When is the best time to edge a bed?

No matter the season, the best time to edge a bed is after a rain. While this may seem like it will make the job dirtier, it will in fact make it easier. Anyone who has used a shovel knows that

When is the best time of year to edge a bed?

The best time of year to edge a garden bed is usually in early Spring or Fall. The reason for this is that the roots of grasses and plants are not as strong, as they just aren’t growing as much. Also, the soil tend to be moist, which makes any form of digging easier.

How deep does the edge need to be?

Roughly 90% of turfgrass roots are in the top 3″ of soil, although it is possible for them to reach 6″ deep in optimum conditions and no mowing. But what we want to focus on is the rhizomes, as that is the mechanism that grass uses to invade flower beds and gardens. And rhizomes from turf grass generally only go 2-3″ deep.

How does grass spread to flower beds and gardens?

Turfgrass reproduces in two ways. First, is by seed, which generally only occurs in late Spring. Un-mowed grass will produce spikelet flowers that will eventually bear seed. This is generally not that effective, and isn’t the primary way grass will invade a flower bed or garden. The second, and primary way grass invades mulched areas is through underground rhizomes.

What are rhizomes?

Rhizomes, also known as runners are white fleshy tubes that resemble roots. But they are actually underground horizontal stems. This is one of the more effective ways in which grass can reproduce, as these underground stems will move laterally from the main plant and send up new shoots in bare spots. And unfortunately for us, they like to invade mulch as it generally keeps the soil moist.

What you want your edge to look like

To have the best looking edge that will require the minimum amount of maintenance, you want the flower bed to have a gradual slope down to the base of a 3″ vertical wall at the sod line. This will sufficiently stop turfgrass rhizomes while allowing for some mulch to spill into the bottom of the trench, but provide enough room so that it doesn’t fill up.

How long will it take to make a new edge?

Making a new edge from scratch, if done in early Spring or Fall can go pretty quickly. I have filmed myself doing this around my flowerbeds and can say that it takes approximately one minute per foot of edge that is 3″ deep and 6-9″ wide. This is heavily dependent on time of year. If you do it in early Spring or fall the root system is not as strong, and it is quite easy to cut through the sod. If you do it in June though, once the grass is thicker, it will take significantly more effort.

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