Nix Groundhogs in the Garden

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Groundhogs can do a lot of serious damage to a vegetable garden. Photo: http://www.farmersalmanac.com

Budding city gardeners are often shocked to discover that they may have to deal with groundhogs in their vegetable patch. I mean, aren’t groundhogs something you find way out in the country? 

Well, that may have been true in the distant past, but in regions where groundhogs (Marmota monax) live, they have long since adapted to suburbs and even the heart of the city, and seem particularly attracted to vegetable gardens. Just because a garden is urban doesn’t mean it will be spared their ravages. Community gardens and collective gardens—also known as all-you-can-eat-groundhog-buffets—appear to be an especially frequent target.

Meet the Neighbor

Distribution of the groundhog (Marmota monax). Ill.: Wikipedia

The groundhog is a large ground squirrel, one of 15 species in the marmot tribe (Marmotini). It’s found only in North America, mostly in the Eastern and Central United States, as well as all across Canada. (In the Western USA, it’s replaced by various smaller ground squirrels, such as prairie dogs.) There are marmots in Europe and Asia as well, although UK gardeners can relax; there are none in your country outside of zoos. Even so, the other marmot species are essentially alpine animals and people rarely garden on barren mountain tops. Only the American groundhog is a lowland species unfriendly to veggies.

The groundhog is a discrete little creature, often living mostly sight unseen in suburban yards and city green spaces. The landowner often only notices its presence in fall when the leaves drop from the trees, revealing its burrow entrance in a hidden corner, under a deck or tool shed or under shrubs. But if he has a vegetable garden, the presence of the groundhog is much more obvious, because, even if it eats a wide variety of plants in the wild, in town, it seems to have a clear preference for vegetables, including cabbages and other crucifers, lettuces, cucumbers, squash, beets, peas, beans and spinach. In addition, it’s quite the glutton: you may see an entire row of cauliflowers disappear in just one night!

Understanding Its Habits

To control a groundhog, you have to understand it.

Not a groundhog colony, but babies ready to leave their mother’s burrow. Mom is certainly not far away. Photo: http://www.pennlive.com.

First, it’s important to comprehend that the groundhog is largely a solitary animal. You’re not dealing with a colony, but just one animal. With the exception of mating season, males and females live separately and the young already leave their mother at about two months old to found their own burrow … which is why, in midsummer, you often suddenly find damage as the young settle into new territory and think your veggies belong to them. In the wild, a groundhog rarely lives long, only two to four years on average, but since each female produces about four pups a year, the population is easily maintained.

Typical groundhog burrow. Photo: wildlifecommandcenter.com

A groundhog lives in a burrow consisting of two to five entrances, long tunnels and at least two compartments: a nest filled with dry grass and a room that serves as a latrine. It will winter in the nest starting in late fall. Since you often see your neighborhood groundhog basking in the sun, rarely far from its burrow, that usually gives a good idea where it lives, often with entrances hidden under a tool shed, a patio or other garden structures. A groundhog will be active both day and night. It actually prefers the presence of humans, taking up residence near our homes, because it sees us as rather clumsy and stupid predators it can easily avoid, while its natural predators (wolves, coyotes, lynx, eagles, etc.) tend to stay away from us.

Groundhogs often chew vegetables (here squash) nearly to the ground. Photo: Diane Vautier

You can suspect a groundhog (or deer) when you find vegetables that are nibbled almost to the ground overnight. An insect simply doesn’t do that kind of damage. By observing what happens to the garden, you should be able to easily confirm if it’s a groundhog, as once it has found your vegetables, it inevitably comes back again and again.

Controls

One urban legend says that if you fill a plastic pop bottle with water and lay it on its side in the vegetable garden, the groundhog will see its image reflected in the side of the bottle and, thinking its territory invaded by a rival groundhog, will flee in panic. If only it were that easy!

A plastic owl may scare groundhogs away … for a while! Photo: http://www.aliexpress.com

However, there are other animal repellents that are more effective. By repellents, I don’t just mean odoriferous commercial products, but any item that scares the animal, whether by sound, sight or smell. So, you can place scented soap in the garden, attach aluminum plates or rags on a cord so that they move in the wind, apply repellents based on rotten eggs or coyote urine, apply blood meal, human hair, pet fur or mothballs to the soil (beware: mothballs are toxic to children!), place a plastic owl or snake in it, play a very loud radio, etc. (For a more complete list of repellents, see Do Animal Repellents Really Work?)

In fact, anything new will scare the groundhog and keep it away from your vegetable patch … for a while, usually no more than two weeks. When it realizes that there is no real danger, though, it will be back. So, the secret to success with repellents is to keep renewing them. If you change them every 10 or 12 days, the poor groundhog will keep feeling there is something new and dangerous each time and will stay away from your vegetables.

Most repellents are DIY household products or inexpensive sprays or granules, but to save you a lot of money, be aware that the ultrasonic devices that are supposed to keep groundhogs away (and indeed, almost any animal away) are no more effective than other repellents, yet are much more expensive. So, you might want forgo that category!

Fido has found a groundhog hole under the tool shed. His presence will make the groundhog very nervous. Photo: lifewithdogsandcats.com

A dog is also an effective groundhog repellent. Groundhogs are instinctively fearful of dogs and most dogs would make short work of a groundhog if ever they caught one, but for a dog to be an effective g-hog repellent, has to be able to roam freely near the garden 24 hours a day. If the dog is tied up or if you bring it indoors at night, the groundhog will quickly learn its limitations or its schedule and use your vegetable patch as smorgasbord when the dog is not around.

Plants That Groundhogs Don’t Like

Another possibility of living in harmony with a groundhog is to only grow plants that groundhogs don’t like to eat. You can find a list of such plants here: Plants Groundhogs Tend to Avoid.

Trap and Release

Sometimes you catch your groundhog without minutes of setting the trap. Photo: http://www.humanesociety.org

You can also catch your groundhog with a Havahart-type trap, a kind of cage with a one-way entrance pests can get into, but not out of. You can set up such a trap yourself or call in an exterminator. Or maybe the animal control department of your municipality can lend you one. For bait, use an apple slice coated with peanut butter. When you’ve caught the groundhog, release it at least 5 miles (8 km) from your home; otherwise it may return. 

The problem then is: where to release it? Farmers will not appreciate the addition of more groundhogs to their property and municipal parks won’t accept them. People have released (illegally!) so many groundhogs on the campus of my local university that, early in the morning, you sometimes see more groundhogs than students.

Fence Them Out

A fence with a bottom part buried underground will keep groundhogs out. Photo: Claire Tourigny

You can also fence in your vegetable patch. Groundhogs don’t jump nor are they really good climbers. A simple chicken wire fence attached to bargain basement wooden stakes is inexpensive and will offer good protection it as long as it is at least 3 feet (90 cm) high aboveground … and if another foot (30 cm) is buried at the bottom. Bend the buried part bend out (not in!) at a 45 ° angle away from the garden. That way, when the groundhog tries to dig, it will keep running into a barrier and soon give up. Of course, you’ll need a gate for your own access … but don’t leave it open by accident!

Hunt the ’Hog!

For a more “muscular” intervention, groundhog hunting is usually allowed in all seasons in areas where it is found … in the countryside, that is, but, of course, not in the city. You’ll probably need a small game hunting license to practice groundhog hunting. Groundhog meat is perfectly edible and quite delicious, tasting something like rabbit.

Drop a Bomb

You can also use a smoke bomb (or hire an exterminator to apply one). You’ll find this in hardware stores or online. This involves plugging all but one of the holes in the groundhog’s burrow, lighting the bomb and placing it inside, then plugging the last hole. If you see smoke, you’ve missed a hole!

The Most Effective Treatment

Motion-activated sprinkler. Photo: dealingwithdeer.com & jungledragon.com.

But the most effective treatment for most gardeners under most circumstances is a motion-activated sprinkler. You install it by connecting it to a garden hose and adjusting it so that it’s directed towards animal’s usual access point. When it makes a visit, day or night, it gets blasted with water. Water is, of course, harmless, but the shock of getting sprayed is terrifying. If there is one thing that a wild animal won’t tolerate, it’s being touched. It will give up any effort to visit your vegetable garden if it gets sprayed every time it tries to approach it.

A motion-activated sprinkler is also effective against deer, raccoons, skunks, cats, pigeons, crows, squirrels … and neighbors who cut through your yard. Any animal, in fact, larger than a chipmunk. If you can’t find this kind of sprinkler in your local garden center or hardware store, it’s easily accessible on the Internet.


So, there are ways of gardening even with a groundhog right next door. You just have to learn to think like one … and then put the proper controls into place.

Plants Groundhogs Tend to Avoid

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20180609 bugspray.com.jpg
Groundhogs are attracted to our gardens and can cause considerable damage. Source: bugspray.com

If there are groundhogs (Marmota monax), also known as woodchucks, in your area, you probably already know it. They’re found across Canada (although absent from a few islands, like Newfoundland, Vancouver and Prince Edward) and throughout the northeastern United States, as far south as northern Louisiana.

There are other species of marmot throughout the entire Northern Hemisphere, but most are mountain-dwelling species, doing little damage to people’s gardens, since few people garden on mountain tops. No so the groundhog! It’s essentially a lowland species and loves the semi-wooded, prairie-like conditions people create.

Also, other marmots tend to live in colonies, while the groundhog is a loner. The mother will, of course, share her nest with her babies, but soon boots them out to live on their own.

Besides being famously used for determining whether spring has come or not (Groundhog Day is February 2), groundhogs can be devastating to home gardens, consuming a vast array of both edible and ornamental plants. They’re found in both the country and the suburbs, even in cities. For example, they seem to absolutely adore community gardens, even urban ones!

Plants Groundhogs Don’t Like

Rather than trying to exclude groundhogs from your garden or to kill them off, it’s perhaps better to learn to live with them … best done by growing plants they simply don’t like. Here are some examples*:

Annuals and Tender Bulbs

  1. Ageratum (Ageratum houstonianum)
  2. Bacopa (Sutera cordata)
  3. Black-eyed Susan (Rudbeckia hirta)
  4. Blanket flower (Gaillardia pulchella)
  5. Dahlia (Dahlia spp.)
  6. Flowering tobacco (Nicotiana spp.)
  7. Gaillardia (Gaillardia pulchella)
  8. Nicotiana (Nicotiana spp.)
  9. Snapdragon (Antirrhinum majus)
  10. Sweet alyssum (Lobularia maritima)

Biennials, Perennials and Hardy Bulbs

  1. American Pokeweed (Phytolacca americana) zone 4
  2. Amsonia (Amsonia tabernaemontana) zone 3
  3. Anemone (Anemone spp.) zones 3 to 6, according to species
  4. Astilbe (Astilbe spp.) zone 4
  5. Baby’s breath (Gypsophila paniculata) zone 3
  6. Blanket flower (Gaillardia spp.) zone 3
  7. Bleeding heart (Dicentra spp.) zone 3
  8. Blue cohosh (Caulophyllum thalictroides) zone 3
  9. Blue Fescue (Festuca spp.) zone 3
  10. Blue lobelia (Lobelia siphilitica) zone 3
  11. Bluestar (Amsonia tabernaemontana) zone 3
  12. Butterfly weed (Asclepias tuberosa) zone 4
  13. Cardinal flower (Lobelia cardinalis) zone 2
  14. Christmas Fern (Polystichum acrostichoides) zone 3
  15. Cinnamon fern (Osmunda cinnamomea) zone 3
  16. Coralbells (Heuchera spp.) zones 3 to 5, according to species
  17. Coreopsis, threadleaf (Coreopsis verticillata) zone 3
  18. Crocosmia (Crocosmia spp.) zone 6
  19. Daffodil (Narcissus spp.) zones 3 to 7, according to species
  20. Daylily (Hemerocallis spp.) zones 3 to 6, according to species
  21. Delphinium (Delphinium spp.) zone 3
  22. Dianthus (Dianthus spp.) zones 3 to 7, according to species
  23. Dwarf mondo grass (Ophiopogon japonicus) zone 6
  24. Evening primrose (Oenothera spp.) zones 3 to 6, according to species
  25. Feather reed grass (Calamagrostis x acutiflora) zone 3
  26. Flag (Iris spp.) zones 3 to 8, according to species
  27. Fountain Grass (Pennisetum alopecuroides) zone 6
  28. Foxglove (Digitalis spp.) zone 4
  29. Gaillardia (Gaillardia spp.) zone 3
  30. Goldenrod (Solidago spp.) zones 2 to 6, according to species
  31. Hay-scented fern (Dennstaedtia punctilobula) zone 3
  32. Hellebore (Helleborus spp.) zone 4
  33. Heuchera (Heuchera spp.) zones 3 to 5, according to species
  34. Heucherella (x Heucherella cvs) zone 3
  35. Holly fern (Cyrtomium spp.) zones 5 to 8, according to species
  36. Hyacinth (Hyacinthus orientalis) zone 4
  37. Interrupted fern (Osmunda claytoniana) zone 3
  38. Iris (Iris spp.) zones 3 to 8, according to species
  39. Jack-in-the-pulpit (Arisaema triphyllum) zone 3
  40. Jonquil (Narcissus spp.) zones 3 to 7, according to species
  41. Lamb’s ears (Stachys byzantina) zone 4
  42. Leadwort (Ceratostigma plumbaginoides) zone 6
  43. Lily of the valley (Convallaria majalis) zone 1
  44. Maiden Grass (Miscanthus sinensis) zones 4 to 6, according to cultivar
  45. Milkweed (Asclepias spp.) zones 3 to 10, according to species
  46. Monkshood (Aconitum spp.) zone 3
  47. Narcissus (Narcissus spp.) zones 3 to 7, according to species
  48. Nepeta (Nepeta spp.) zone 4
  49. Oregano (Origanum spp.) zones 3 to 7, according to species
  50. Ornamental onion (Allium spp.) zones 3 to 5, according to species
  51. Ostrich fern (Matteuccia struthiopteris) zone 3
  52. Pasque flower (Pulsatilia vulgaris) zone 3
  53. Peony (Paeonia spp.) zone 3
  54. Pink (Dianthus spp.) zones 3 to 7, according to species
  55. Plumbago (Ceratostigma plumbaginoides) zone 6
  56. Red hot poker (Kniphofia spp.) zones 5 to 7, according to species
  57. Red valerian (Centranthus ruber) zone 4
  58. Ribbon grass (Phalaris arundinacea ‘Picta’) zone 3
  59. Royal fern (Osmunda regalis) zone 3
  60. Russian sage (Perovskia atriplicifolia) zone 4b
  61. Sedum (Sedum spp.) zones 2 to 10
  62. Soapwort (Saponaria spp.) zone 3
  63. Sundrops (Oenothera spp.) zones 3 to 6, according to species
  64. Sweet woodruff (Galium odoratum) zone 3
  65. Torch lily (Kniphofia spp.) zones 5 to 7, according to species
  66. Tritoma (Kniphofia spp.) zones 5 to 7, according to species
  67. Turtlehead (Chelone spp.) zone 3
  68. Wild ginger (Asarum spp.) zones 3 to 6, according to species
  69. Windflower (Anemone spp.) zones 3 to 6, according to species
  70. Wood fern (Dryopteris marginalis) zone 3
  71. Wormwood (Artemisia spp.) zones 2 to 8, according to species
  72. Yarrow (Achillea spp.) zone 3

Herbs

  1. Catmint (Nepeta cataria) zone 4
  2. Chives (Allium schoenoprasum) zone 2
  3. Feverfew (Tanacetum parthenium) zone 5
  4. Garlic chives (Allium tuberosum) zone 3
  5. Horehound (Marrubium vulgare) zone 4
  6. Lavender (Lavandula spp.) zones 5 to 8, according to species
  7. Lemon balm (Melissa officinalis) zone 3
  8. Oregano (Origanum spp.) zones 3 to 7, according to species
  9. Rosemary (Rosmarinus officinalis) zone 7
  10. Scented geranium (Pelargonium spp.) annual
  11. Sweet woodruff (Galium odoratum) zone 3
  12. Tansy (Tanacetum vulgare) zone 3
  13. Thyme (Thymus spp.) zones 3 to 5, according to species
  14. Wormwood (Artemisia spp.) zones 2 to 8, according to species

Vegetables

  1. Garlic (Allium sativum)
  2. Onion (Allium cepa)
  3. Pepper (Capsicum annuum)
  4. Potato (Solanum tuberosum)
  5. Pumpkin (Cucurbita pepo)
  6. Rhubarb (Rheum x hybridum) zone 3
  7. Tomato** (Solanum lycopersicum)
  8. Zucchini (Cucurbita pepo)
**In some areas, groundhogs will eat tomato fruits, but not foliage.

Trees and Shrubs

  1. Colorado Blue Spruce (Picea pungens glauca) zone 3
  2. Forsythia (Forsythia spp.) zones 4 to 6, according to species
  3. Golden rain tree (Koelreuteria paniculata) zone 6
  4. Gray Birch (Betula populifera) zone 2
  5. Heather (Calluna spp.) zone 5
  6. Japanese Holly (Ilex crenata) zone 6
  7. Japanese Maple (Acer palmatum) zone 6
  8. Juniper (Juniperus spp.) zones 2 to 7, according to species
  9. Lilac (Syringa vulgaris) zone 3
  10. Peony, tree (Paeonia suffruticosa) zone 4b
  11. Pine (Pinus spp.) zones 3 to 10, according to species
  12. Potentilla (Potentilla fruticosa) zone 3
  13. Privet (Ligustrum spp.) zones 3 to 7, according to species
  14. Rose of Sharon (Hibiscus syriacus) zone 6
  15. Rosier (Rosa spp.) zones 2 to 9, according to species
  16. Staghorn Sumac (Rhus typhina) zone 3
  17. Sweet Fern (Comptonia peregrina) zone 3
  18. Wisteria (Wisteria spp.) zones 4 to 8, according to species
*The lists above are largely based on observations rather than formal studies and are therefore subject to modification, doubly so because groundhogs in one area may have different food preferences than those in other areas. Please don’t hesitate to suggest additions and corrections.