Soil Knife vs. Trowel: Which One to Use for Each Garden Job

Soil knife vs. trowel: the short answer

Use a trowel when the job is moving soil and a soil knife when the job is cutting. A trowel is a small hand shovel with a dished blade, and University of Florida’s tool guide assigns it one task: planting small plants. A soil knife, also sold as a hori hori, is a heavy, slightly concave steel blade with one straight edge and one serrated edge. Colorado State’s master gardeners list its uses as weeding, transplanting, sod cutting and dividing perennials.

Most gardeners end up owning both, because a morning in the garden usually includes scooping and cutting within the same hour. If you are buying only one and your work is mostly maintenance in established beds, the knife covers more ground. If you mostly fill containers and set out bedding plants, start with the trowel.

Soil knife vs. trowel at a glance

	Trowel	Soil knife (hori hori)
Blade	Dished scoop with a rounded or pointed tip	Slightly concave, normally about 6 7/8 by 1 3/4 inches
Edges	Not sharpened	Sharp on both sides, one serrated, semi-sharp point
Overall length	Varies with handle	11 to 15 inches
Carries soil	Yes	Poorly
Cuts roots, sod, twine	No	Yes
Depth marks	On some models	On some models
Needs a sheath	No	Yes

The dimensions in the knife column are the ones Colorado State gives for a typical hori hori, with blades made of either carbon steel or stainless steel. Trowels vary far more by maker, so try the grip in your hand before you choose one.

When a trowel is the right tool

Anything that involves volume belongs to the trowel. Filling pots with mix, digging holes for bedding plants in soil that has already been loosened, backfilling around a transplant and topping up a container with compost are all scooping jobs. A soil knife can open the hole, but each stroke moves a fraction of what a dished blade lifts, and loose mix slides off its sides.

The trowel also suits crowded plantings where you do not want a sharp edge near neighboring crowns. Setting a flat of annuals into a prepared bed goes quickly with a trowel in one hand and the plant in the other. Our list of essential gardening hand tools covers what else belongs in the same bucket.

When a soil knife is the right tool

Division is the clearest case. Iowa State’s guide to dividing perennials calls for a sharp knife or spade to separate clumps, with each division keeping several shoots and a portion of the root system. The serrated edge of a soil knife saws through a dense crown that a trowel can only bruise. Iowa State times the job for early spring as foliage emerges, which is April in Iowa, or for fall at least 4 to 6 weeks before the ground freezes. The step-by-step is in how to divide perennials.

Root work at planting is the second case. Shrubs and trees grown in containers often have roots circling the inside of the pot. Penn State Extension says it is best to sever those roots with a sharp utility knife or handsaw before planting, and notes that the cut roots regenerate quickly into the surrounding soil. A soil knife does this in a few strokes. Florida’s guide likewise lists loosening a rootbound plant from its pot as a garden knife task.

Weeding is the daily use. Colorado State puts weeding first in its list of jobs for the knife and describes the semi-sharp point as suited to digging and prying. Slide the blade down beside the root and lever the handle back to lift it. Add cutting twine and slicing sod, and one tool replaces several trips to the shed.

Bulbs: the job both tools share

Bulb planting needs a hole of a known depth, and either tool can make one. Iowa State’s planting depths are 6 to 8 inches for tulips and daffodils and 3 to 4 inches for crocus and grape hyacinth, with October as the ideal planting month in Iowa. The general rule from the same source is to plant at two or three times the bulb’s maximum diameter.

Some soil knives have a ruler marked on the blade, and Colorado State notes that the tool can double as a measuring device when planting bulbs into an established bed. A typical 6 7/8 inch blade pushed in to the handle lands within the tulip range, so the tool doubles as its own gauge. Trowels with depth marks do the same job and remove more soil per stroke, which helps when a wide hole will hold several bulbs. For choosing what to plant, see fall-planted bulbs for spring color. Garlic cloves go in during the same season, and how deep to plant garlic covers that crop.

How soil type changes the choice

In loose soil, such as a raised bed filled with compost-rich mix, the trowel is faster for nearly everything except cutting. In hard ground the balance shifts. Colorado State notes that the serrated edge of a hori hori cuts through roots, tubers and tough soil, and the semi-sharp point is suited to digging and prying. A narrow blade enters compacted or root-filled ground where a wide scoop skates across the surface, so in clay or under trees the knife often opens the hole and the trowel clears it.

Choosing and caring for both tools

For a soil knife, choose between carbon steel and stainless steel blades, and look for a ruler on the blade, a non-slip handle and a hilt that keeps your hand from sliding forward. Buy a sheath with it. The blade is sharp on both sides, and a bare knife loose in a tool bucket is a hazard every time you reach in.

Florida’s tool guide gives the care routine for any hand tool: remove soil after use, clean the tool, and store it in a dry location. It also suggests spray painting handles a bright color such as safety orange, which helps when a trowel disappears into mulch. University of Georgia Extension recommends sharpening and oiling blades at the end of each season and treating wooden handles with linseed oil. Our guides to removing rust and caring for wooden handles go through both steps.

After cutting into diseased roots, disinfect the blade before moving to the next plant. University of Maryland Extension’s method is 70 percent alcohol, or bleach diluted one part to nine parts water. Rinse the bleach off afterward, because it is corrosive to metal.