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How to control slugs in your garden

April 6, 2022   •   Leave a Comment

Hostas are a prime target for slugs.
Hostas are a prime target for slugs.

by Nancy Szerlag

Slugs are the bane of many gardeners’ existence. In the dark of night these slimy characters chew away at the garden, leaving it in tatters by sunup. A mild winter combined with a cool, wet summer can send the dastardly slug population soaring. And a single slug will eat 30 to 40 times its weight in vegetation daily, so a handful of slugs can do a great deal of damage in a short period of time.

Ridding the garden of slugs is a hard fought battle for many gardeners. Commercial slug baits containing metaldehyde are not recommended because they are highly toxic to small animals, children and birds. Also, if used regularly, the slugs seem to build up immunity to the ingredients.

Beer traps (tin cans filled with fresh beer, or a solution of sugar, water and yeast) will lure the slugs to their demise by drowning, but they attract only those sliming around in close proximity to the slug saloon. If you have a large garden, to get any measure of control you have to set out a lot of traps and they need to be cleaned and refilled every few days.

Products with iron phosphate are both effective and easy to use for controlling slugs. Plus, some are organic products that will not harm pets and wildlife. Iron phosphate breaks down to become part of the soil, and is combined with an effective lure that slugs consider a tasty treat.

Because slugs feed mostly at night, it’s best to apply the iron phosphate products in the evening. Slugs like damp areas, so if the soil is dry, wet it before applying. While the granules will not dissolve in the rain, they must be reapplied as they are consumed. To be truly effective the product needs to be in place as the slug eggs hatch out, so it should be reapplied according to package directions throughout the summer. A very heavy infestation of slugs may take two years or more to control.

We are better able to combat slugs effectively, like any garden pest, if we become familiar with their feeding habits and life cycle. Unfortunately, slugs (like worms) are hermaphroditic, having both male and female sex organs, so every slug that reaches adulthood in the garden has the potential of procreating more slugs by laying anywhere from 20 to as many as 100 eggs once or possibly twice a year.

When digging in the dirt, should you come upon a cache of tiny translucent spheres that look like little plastic beads sitting in the soil, you have found a stash of slug eggs. I often find them in the soil under decorative stones and containers that sit in the garden. When I find a mass of eggs, I crush them between my gloved fingers or carefully scoop them up and dump them in the trash. In spring when the ground warms, the eggs hatch and the tiny slugs immediately become active feeders. Mature slugs are able to overwinter in the soil and are ready to feed as soon as tender shoots emerge from the soil in spring.

So, unlike the Integrated Pest Management strategy used for most garden insects, where products are not recommended for use until the insect damage becomes unsightly, if your garden suffered slug damage last year, you should begin control measures as soon as the hostas and other plants poke their noses through the soil in spring.

Using their rasp-like mouth parts, slugs bore through the leaves, fruit and flowers of many plants, leaving telltale round holes behind. Other signs that slugs are at work are the trails of shiny, silvery dried slime left on the surface of the soil. Slugs are particularly fond of hostas, petunias and delphiniums. The leaves of hostas under attack will soon look like Swiss cheese.

Slugs do most of their feeding at night, although they are also active on cool, overcast, rainy days. Because slugs seek shelter in soil cracks and under debris during the day, many gardeners never see them and mistakenly blame other insects for their damage. Treatment with a broad-spectrum pesticide is useless because these insecticides are ineffective for use on slugs, which are members of the mollusk family. However, insecticides unfortunately do kill off a slug’s natural predators, including rove beetles, daddy long legs spiders, centipedes, fire fly larvae and soldier beetles—this helps to increase the slug population. Thus, avoid this scenario.

To check for slugs, peruse the garden with a flashlight a couple of hours after sundown. Be sure to look at the undersides of leaves. Some gardeners enjoy hand-to-hand combat, and delight in hand-picking and dropping their prey in cans of soapy water. But hand-picking can be tedious and tiny hatchlings are easily missed in the dark of night.

It’s not always necessary to treat an entire garden for slug infestations because there are certain plants that are slug resistant. Artemisia, bleeding heart, coral bells, tickseed, goatsbeard, lamb’s ears, candytuft, foxglove, Jacob’s ladder, and most herbs seem to be immune. However, common slug targets include begonia, hollyhock, marigold, primrose, violets, bellflower, geranium, daylily, iris and snapdragon. Lettuce, cabbage and rhubarb are favorite foods of slugs, along with the fruits of strawberries and tomatoes. Ivy and succulents are also prime dining fare.

As a shade gardener and grower of hostas, I’ve battled slugs for a number of years and tried many organic controls including beer traps, organic dusts and repellents. They all work to a degree, but to be truly effective they need to be attended and monitored on almost a daily basis. I don’t have that kind of time. But the iron phosphate products have given me the time to stop and smell the roses. I am happy to say I am finally winning my war on slugs in an environmentally friendly manner.

Nancy Szerlag is a Master Gardener and Master Composter from Oakland County, MI.

RELATED: Keeping slugs off hostas

RELATED: Killing slugs with caffeine

Filed Under: How-To Tagged With: beer traps, control slugs, iron phosphate, slugs

There are more options for shade gardens than just hostas

April 6, 2022   •   Leave a Comment

Coral bells (foreground) and lungwort (background) are both effective plants for shade gardens.
Coral bells (foreground) and lungwort (background) are both effective plants for the shade garden. (Photo: Terra Nova Nurseries)

by P.J. Baker

If you have quite a bit of shade at your house, everyone says, “Oh, you want hostas. That’s what grows in shade gardens.” Well, if you go out in the woods in Michigan you will find many flowers, but no native hostas. Native to China and Japan, hostas are wonderful shade plants. Used in combination with other shade plants, or using 2 to 3 different hostas together, they can be beautiful.

I have a shade garden that is so full I do not have room for anything else. However, there are no hostas—there is no space left to plant them. I have flowers all summer long and interesting foliage when there are no flowers. My hellebore (Lenten rose) starts blooming in March, with or without snow, and it is evergreen. I like it under trees. The only maintenance is cutting off old dead leaves in the spring. Another early bloomer that has variegated foliage is lungwort (Pulmonaria). These have blue and pink flowers in April or May. This groundcover looks great even when not flowering. Note that it can spread easily by seed.

Perennials

Some of my favorite perennials for shade are columbine, astilbe, brunnera, coral bells, foxglove, epimedium, geranium and various ferns. Astilbe flowers at different times and if you get several different hybrids, there can be one blooming most of the summer. Some also have reddish leaves and all have lacy foliage. The flowers of brunnera look like forget-me-nots. Coral bells have many variegated and ruffled edges on their foliage. Geranium likes sun or shade, often has fragrant foliage, and has different bloom times. These perennials are just a few of many that are available.

Grasses

There are also several grasses that can be planted in the shade. This also adds winter interest; the dead flower heads are lovely all winter. Cut most grasses to ground level in the spring. Several grasses for shade are Northern sea oats, tufted hair grass, variegated purple moor grass, Japanese forest grass (Hakonechloa), and many types of sedges. These grasses range in height from 6 inches to 3 feet. The foliage is found in an assortment of colors such as blue, yellow, green, and variegated.

Bulbs

Bulbs for the shade include Spanish bluebell, fritillaria, Italian arum (Arum italicum), dog’s tooth violet or trout lily, winter aconite, and great camas (Camassia leichtlinii). Camassia is a native bulb used by Native Americans for food. For interesting variegated foliage in winter and beautiful orange berries, use the Italian arum. Most of the bulbs bloom in the spring for a lovely early show. Then in late June after the foliage turns yellow, you can plant shade annuals in the area and have an all-summer show.

Annuals

There are many annuals that can be used in the shade besides impatiens and begonia. I like coleus, with its striking foliage, and torenia.

Shrubs

Shrubs are a staple of the garden and there are several that prefer the shade. If you have a protected area on the north or east side of your house, plant broadleaf evergreens. These include rhododendrons, azaleas, kalmias, and euonymus. There are evergreen and deciduous hollies (winterberry) that also have berries for winter interest.

More shade shrubs include fothergilla, summersweet, smooth hydrangea, panicle hydrangea, oakleaf hydrangea, and Virginia sweetspire. Hydrangeas also offer winter interest with their dead flower heads. If needed, the smooth and panicle hydrangeas may be cut down to about 12 inches in the spring. Some offer great fall color. Oakleaf hydrangea turns red in fall, although because of winter injury it may not flower every year; do not cut it down in the spring. Fothergilla turns yellow in fall. Virginia sweetspire is native and turns reddish-purple, often persisting into winter.

I encourage you to study and look around your neighborhood for a summer before you start your shade garden. Put a plan on paper; you will be grateful you spent the time planning your garden. You may decide to include hosta plants, or like me, you may find you ran out of space.

RELATED: Janet’s Journal: Shady Goings-on

ELSEWHERE: Made in the Shade Garden

Filed Under: Feature Tagged With: coral bells, hosta, lungwort, shade gardens

How do I care for transplanted roses in spring?

March 31, 2022   •   Leave a Comment

climbing roses
On your climbing roses, if you have laid the canes down on the soil and covered them up, now is the time to uncover and gently lift the canes up and attach them again to their support structure.

Last October, I transplanted two climbing roses and a standard rose bush. What should I be doing for them this spring?

There are four basic tasks for transplanted roses. First, carefully remove winter protection about the time you see crocus and tulips emerging from the ground. That indicates the ground temperature is warming slowly and your roses will be taking up moisture soon. If any of your roses were grafted, expose the graft union and check for growth buds on the rootstock (below the graft). You do not want to encourage these rootstock sprouts—remove them. On your climbers, if you have laid the canes down on the soil and covered them up, now is the time to uncover and gently lift the canes up and attach them again to their support structure.
The second task is pruning in April, when you start to see bud swell on the canes and branches, or around the time forsythias bloom. Remove dead branches and prune for air circulation, crossing branches and aesthetic cane length based on the supports.
The third step is their first feeding, which can be done at pruning time. A general slow-release fertilizer blended for roses is great. Spread it at the dripline and gently scratch it into the soil. Roses are heavy feeders. Many rose growers use organic supplements, such as fish emulsion or additional slow-release granular fertilizer, once a month until August to keep them healthy against disease and insect attack.
Lastly, as the roses start to push out leaves and new growth, apply a preventative spray for fungal diseases like black spot. A horticultural oil spray later in May into June can help with insect problems.

Related: How to grow great roses: Pruning and fertilizing

Filed Under: Ask MG Tagged With: climbing, roses, standard, transplanted

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