Little Critter Garden Defense: Voles, Moles and Friends

Little Critter Garden Defense: Voles, Moles and Friends

Posted by Kerry Kelley on Nov 1st 2022

Gardening can be a challenge for many reasons--limited time or space, difficult climate, too much shade (or sun), and poor soil, for instance. Proper plant choice can counter many of those problems, allowing us to have a beautiful garden despite the obstacles. Amending the soil or growing in containers can solve further issues, giving us a broader range of plants to grow.  And thus we garden on, because we love it so.

But others love our gardens, too—sometimes a little too much. I remember a few years back, feeling so satisfied after I had planted my shady border on the north side of my house in the late spring. Some of my favorite plants finally had a place-- 'Soft Caress’ mahonia, a rather difficult to find ‘Pink Frost‘ Illicium (variegated anise “tree”), ‘Evergold’ carex and various hosta, ferns, and Solomon's seal.. It was a glorious mix of textures and subtle color, and the plants settled in nicely—or so I thought.

Come late summer, I noticed that a small branch of the Illicium was dying back. Ok, says I, perhaps I need to lighten up on the water--the root system had been small when I planted, my soil isn't the best, those things happen. I trimmed it back, watered more carefully, and assumed all would be well. But by late fall the plant was clearly in decline, now down to one main branch. Ah, why is it always the plants you love the most that leave you? I blamed myself for overwatering and hoped for recovery. After all, the mahonia a few feet away was doing fine, and you know, those things happen in a garden.

Come spring, after a winter with more than usual snow cover, the illicium looked no better, and now a branch (really a stem) of the mahonia was toppled over and wilted. Ok, those things don't happen. I dug around a bit next to the mahonia to check for root rot. The next thing you know, the whole plant, which was originally 2 feet across, came up in my hand. There were no roots to be seen. What the…..? Frantic now, I mentally crossed my fingers and checked the remaining bit of my precious illicium. Yes, it had suffered that same cruel fate. 

Some of you may have already guessed the problem—voles. Resembling blunt-snouted mice, these vile creatures sneak around under your mulch and feast on the lifeblood of your precious plants. They're active all winter, tunneling through the snow cover that usually provides a protective layer of insulation for your plants. Unfortunately, it also provides a protective layer of invisibility for those wretched rodents. The tunnels are only about an inch deep, and not really noticeable unless you dig gently around looking for them. Which I did that spring, and they were everywhere in that bed, and led under the fence to a bed in the common area bordered by the sidewalk. Needless to say, I was not a happy camper.

I spent the rest of that spring and summer as obsessed as Elmer Fudd with that wascally Bugs Bunny. I dug up all the remaining plants in the bed and containerized them temporarily while I gave the enemy everything I had. This was one time I was glad to have a small townhouse garden. I don’t think I could’ve won with anything larger. I don’t know if it was one vole or many, but by fall I was finally vole-free, and they have not returned........so far.

I’m sure many of you can relate, whether you’ve won the battle or are still fighting. Gardening isn’t supposed to be stressful, so here are some tips to help you combat those devilish garden critters that are making war, not love!

Lots of little rodents may inhabit your garden and not all are harmful. So how can you tell the difference?

Difference between mice, voles, moles, shrews, and chipmunks:

Mice:

  • Can be brown to grey; house mouse usually grey, white-footed mouse usually brown with white belly
  • More pointed snout
  • Ears larger relative to head size
  • Slimmer build and longer tail that is the same length as the body
  • Omnivorous--eat seeds, insects
  • Nests more likely to be found above ground when living near homes, but in wilder areas will make burrows
  • Common outside nesting areas are sheds,
    rock piles, firewood stacks, deck boxes, overturned pots--especially areas that haven't been recently disturbed. They prefer to travel in closely sheltered areas, generally avoiding open ground where predators may attack
  • Look for nests of shredded paper, fabric, grass--almost anything they can chew up for warmth and protection
  • Not usually harmful to garden plants, but white-footed mice can spread Lyme and other tick-borne disease
  • You'll never have just one (for long)!

Voles:

  • Usually chestnut brown with black, but can be greyish
  • Roughly the same size and color as mice
  • Blunter profile and smaller eyes
  • Thicker build with shorter tail
  • Serpentine "tunnels" are very shallow trenches--usually no more than 1-2" wide and deep
  • Above ground foraging species are less common--they chew lawn grass into "runways" that connect to their burrows
  • Tunnels of one colony may cover as much as 40 square feet
  • They may use mole tunnels if present
  • Herbivorous: eats plant roots, tubers, bulbs, seeds and other vegetation; above ground foragers gnaw bark of shrubs and trees and may girdle the stems resulting in dieback
  • Do not hibernate so they are active in winter also, especially under snow cover
  • Usually live in a small family colony, but colonies of ground foraging species may number as many as 100

Moles:

  • Usually greyish
  • May be slightly larger than mice or voles
  • Pointy pink nose, small eyes, and no visible ears
  • Large paddle-shaped clawed feet for digging
  • Tunnels leave large ridges of dirt in lawns and beds: "molehills"
  • Primarily insectivorous: eats worms and insects, and if in your lawn is likely eating grubs: effective removal strategy means also treating with milky spore for the grubs to extinguish their primary food source

Shrews:

  • Usually greyish brown, lighter underneath
  • Smaller than mice or voles
  • Pointy nose with almost very small eyes and flattened ears
  • Tail about 1/3 body length
  • Live under leaf litter and do not make tunnels; however may use tunnels made by other rodents
  • Solitary except when mating
  • Primarily insectivorous: eats slugs & snails, caterpillars, worms, beetles, but occasionally mice or small birds
  • Rarely a nuisance in the garden, and may be helpful with slug, snail, and beetle control so should ideally be left alone

Chipmunks:

  • Brown with black and white stripes down the back
  • Larger with bushy tail
  • Will burrow, sometimes under foundations or walkways. But according to the Humane Society of the US, "there are no documented cases of a chipmunk burrow causing structural damage."
  • No evidence of digging is usually found as they replace the soil in the original hole to escape detection
  • Usually solitary except when mating
  • Omnivorous: eats insects, baby mice or birds, seeds, nuts, fruits, bulbs, etc.
  • Plants may be damaged while collecting seeds or fruit, bulbs may be eaten. May disturb newly installed plants or seedlings.
  • Personally I have not experienced any damage from chipmunks. I have seen them sitting in the pot with my tomatoes, but they've never touched one. They seem quite satisfied with the birdfeeder overflow.

Tips for control of Voles and Moles:

  1. Castor oil products, either bought or homemade. These can be sprayed on lawns or beds, or granular products can be mixed with the soil when planting. The castor oil will irritate their eyes and nose, thus encouraging them to go elsewhere. Probably best used in combination with other treatments for large areas or large infestations. Repeated treatments will be necessary. I added hot pepper and garlic to a solution of equal parts dish soap, water, and castor oil, and thoroughly saturated all the runs, 3 times a week for the first week, once a week for the following month, and every two weeks after that. I made sure to also spray the solution in a strip on the other side of the sidewalk that borders the bed, so they didn't think about going in that direction. I started at the end closest to the house and worked my way outward to the fence line. I also treated the bed and common area about 6 inches out from my fence. I kept it up until late fall. Yes, it was a pain, but fortunately it worked.
  2. Soil Perfector by Espoma. This can be installed as a ring around individual plants or beds about an inch or two deep for voles. For moles it can be added to the soil in the planting holes or mixed with soil used to fill in tunnels. This is a natural kiln-fired ceramic material that looks like very small grainy rocks. It forms an abrasive barrier that discourages rodents from digging. It is also an excellent organic soil amendment that improves drainage and moisture retention. This does not break down in the soil, so only one application is necessary. I used this when I replanted for extra insurance. My soil needed it, anyway!
  3. Physical exclusion. Installing a maximum 1 inch wire mesh or small chicken wire in or around beds or plants. Line bulb planting holes, thus "caging" your bulbs, top, sides, and bottom. Don't let the bulbs sit on the wire--add some soil on bottom and sides so they can't be reached by a prying snout. You can also cage rootballs of plants in the same way--the roots will grow through the chicken wire eventually, but at least there will be some roots they can't get to. Lay wire mesh in beds just barely under the mulch so as to be unobtrusive, with sides and ends and buried at least 6 inches deep, preferably 12 inches. This tends to be better than trying to "fence" in above ground, as some critters may simply climb over. It's important to make an L-shaped barrier with the L 6 to 12 inches wide to keep out the little bulldozers you're trying to exclude. Don't add too much mulch on top, or the voles will have their way with you anyway. Beds can be edged with bricks or long pavers installed in a vertical fashion, thus providing a barrier underground. Once my voles had departed, I added BACK a similar border under my fence that I had dug up years before. I always wondered why that was there--even if not intended as a vole barrier it had likely acted as one. I bought a roll of the wire mesh, but due to sheer laziness I have never installed it. I hope I never have to, but it's at the ready just in case.
  4. Remove their protection. Thick groundcovers like pachysandra are a no-no. They provide perfect cover, and allow them to easily move from one area to another. It also makes it harder to see any tunnels when you're looking for them. Mowing the lawn short, especially just before winter, is also suggested. Landscape or weed block fabric is also not recommended, as it allows them to move about completely protected and unseen.
  5. Protect crowns and stems of plants. You can put a mesh "collar" around any already planted specimen you need to protect. Dig a narrow circular trench at least 6 inches deep around the plant, disturbing as few roots as possible, and bury a ring of galvanized mesh or small chicken wire. Leave a collar of 2-6 inches, depending on the size of the plant. For smaller seedlings or transplants you can remove both ends of an aluminum can and place it around the plant, pushing into the soil about 1/2 to 2/3 up. Pieces of very thick PVC pipe can be used the same way, if that's what you happen to have. Tree guards can be used to protect bark.
  6. Trapping. I know many have resorted to this, and indeed it may at times be necessary. Regular mouse traps baited with peanut butter can be set in the runs to catch voles. Having seen a mole trap once though, I know I never want to see one again. But it is a viable option for those that can handle it.
  7. Baiting. This will likely need to be done by a professional, as the chemicals used may not be allowed otherwise. Certainly not a good solution for those with pets and small children.
  8. Most importantly, avoid attracting them! Keep birdfeeders and compost piles as far from your prized plants as possible. Keep leaf litter and plant debris to a minimum. Place only the absolute minimum layer of mulch that is needed to protect plant roots and never pile mulch around crowns or stems of plants or trunks of shrubs and trees. A 1-2" deep layer of stone or gravel mulch will discourage their tunneling. Even if you don't like the look for the long run, it can help temporarily while you're trying to take back control.

For moles, you may need to treat for grubs:

  1. Look for grubs. Peel up about a square foot of turf about 2-3 inches deep. Look for white C-shaped grubs, usually with brown heads. Later in the season these will start to burrow down 6 to 8 inches for winter. The grubs are the larval form of beetles that will hatch next year. If you have more than 10 you probably have a problem that warrants treatment. It should be noted how many types of grubs are seen, and an ID should be made.
  2. Apply milky spore, a naturally occurring bacteria that can be applied for Japanese Beetle grubs ONLY. This will only work with a heavy infestation in adequately warm conditions. The bacteria spread only after ingested by a grub at the proper temperature. This may require additional applications and may take a few seasons before control is complete. Milky spore is only recommended if you have visible lawn damage from the grubs; otherwise it is likely to be ineffective as the populations are likely too low for the bacteria to spread adequately.
  3. Apply beneficial nematodes. You will need to choose the appropriate species depending on the type of grub and how deep they live--hence the necessity for ID mentioned above. Your county or state cooperative extension service can be your best friend here. Nematodes will be sterilized by exposure to direct sunlight, rendering them unable to reproduce and spread. Given that, they should be applied in early morning or late evening, or on a cloudy day, and to moist soil only. For best assurance of sustaining nematode populations they may need to be applied once or twice a year for two years, with late summer or fall being preferred.
  4. Use natural repellents to discourage adults from laying eggs. Rodent or deer repellents with garlic or pepper may be applied to the lawn and garden before and during the egg-laying season for the particular beetle. No eggs, no grubs.

Extra tip to lessen the number of ticks if you have mice around your home: I have had good reports from users of TickTubes by Damminix. The tubes are filled with cotton balls that contain permethrin, a tick killing pesticide. The mice will take the cotton balls back to their nests, where it acts essentially like a tick collar for a dog or cat. There are other similar devices also available--you may read a report of studies from the National Institutes of Health here.

How have you dealt with little critters in your garden? Pass on your thoughts, tips, or questions--the more we share, the more we learn!