Archive for soil health

Natural Slug and Snail Control In Your Portland Landscape

California Brown Snail in Portland, OR

Slugs and snails do a lot of damage in Portland gardens.

Slugs and Snails in your Portland Landscape

My history with slugs in the garden

I was never thrilled with my options for dealing with slugs and snails.  In the 80’s we had the typical little gray French slugs and snails in our gardens and they were pesty enough.   I had often just hand picked them and kept the numbers down.  Then in the 90’s we started seeing California Brown Snail and they added significantly to the total damage.  It was too much for me to manage organically.  The beer bait didn’t work for my garden on a city sidewalk in NW Portland’s Nob Hill District.  Dogs would drink the beer which is NOT good for them and the traps looked tacky too. Using the snails for escargot doesn’t work as a pest management practice since the typical serving is six 1 ½” snails per person.  My family would  never go for Escargot anyway.  They are not adventurous diners.

 

Slug Bait Problems

NW Native banana slug does not damage living leaves

The banana slugs only eat leaves that are decaying or broken. They also pollinate native spring flowering plants on the forest floor. I did not like leading them to slaughter.

I started using the “pet safe” iron phosphate slug bait.  It was an easy method to cut down the population compared to beer baiting or hand picking them. The problem with slug bait is that it does not discriminate. It would lure innocent NW native banana slugs to their death along with the real culprits that did the damage to my plants.

Another problem with slug bait is it doesn’t protect your plants immediately.  Slug bait lures the slugs to the bait but does not kill them right away.  They have time to do a lot of damage before they sicken, stop feeding and then die.

Worms die from iron poisoning

The major issue is the iron phosphate remains in the slug’s body and breaks down and ends up in the soil.  This iron residue left behind in the soil created a toxic environment for worms, the creatures who keep our soil healthy.

I didn’t notice it myself until I got raised beds in my community garden.  I noticed a steady decline in the population of worms in my beds.

Copper wire around vegetable bed deters slugs

Daizzie inspecting the copper wire which keeps slugs out of my veggies by producing an electric shock.

 

There is an inert ingredient in the pet safe slug bait that combines with an active ingredient to kill earthworms.  They die from iron poisoning.  The combination was also causing harm to wildlife and to small domestic animals so it was time for me to make a big change.

Slug Bait Alternative-Natural Slug Control

Ann Lovejoy is a trusted resource and treasure for Pacific NW Gardeners.  She is the one that made the connection between the iron phosphate “pet safe” slug bait and the harm it was doing.   Read more about how slug bait kills worms. 

She made several suggestions for what to use instead of slug bait.  My favorite is using liquid caffeinated coffee sprayed onto plants as a repellent.  I tested it this past fall to great success.  I was able to protect my kale crop from slugs.  I purposely sprayed coffee on only half the plants as a test.  The plants I did not spray were missing half their foliage.  The plants I sprayed had no holes or missing foliage.   I sprayed at least once a week during the fall rains.  Ann says a direct spray of coffee will kill the slugs but I could not tell if this was a success.   I sprayed the coffee directly on slugs but when I came back the next day the sprayed slugs were no where to be seen.  They may have crawled off and quietly expired but I was not sure. Maybe my coffee wasn’t strong enough. I will do more testing now that the soil has warmed up enough for new slugs and snails to hatch. I’ll post again and share what strength of coffee it takes for an obvious demise.

I can’t wait to share this with my landscape design clients.  Many clients have pets.  The fact that pet safe slug bait is toxic needs to be shared.

Another option to deal with slugs in raised beds is to line the edge of the bed with copper.  I used a copper ground wire but you can use sticky copper tape available at most garden centers and it will last maybe one garden season if you are lucky.  It is easy to buy and apply to your raised beds, pottery and containers.

Slug or Snail?

What’s the difference between slugs and snails?  Slugs and snails are pretty much the same animals according to Robin Rosetta, Associate Professor at OSU.  Over time slugs evolved out of a hard shell so they could move through cramped spaces and allow them to get down into the soil to find food and protection.  Apparently, there is still sort of a shell under their hump like mantle.  Snails still have a shell and so are restricted to above ground activities.  They use their shells to survive inclement weather and are protected from some enemies and predators.

Safe Soil in the City

Portland landscape designer Carol Lindsay

Daizzie and I in my edibles garden

Safe soil in the city – smart and healthy practices for urban gardens

I love having a vegetable garden. It’s healthy, right? I love eating kale and I grow a lot of greens for smoothies year-round.  There are a few concerns about growing food in urban areas. Two concerns that apply to us all, city and suburban, are lead paint and lead exhaust from the past in our soils. Let’s be practical not scary about this.

Is my food safe to eat? What are the most important practices I can do and how can I keep it simple?  My garden is below Highway 30.  It’s an old heavily traveled highway so our soil has years of exposure to lead exhaust.

There’s no way I’d grow my food in the ground here.

My current garden practices

I’ve been assuming my food is safe to eat because:

Our community garden has raised beds with new clean soil from just three years ago.
I apply lots of compost at least three times a year.

Carol's winter kale

My garden supplies me with year round greens like kale.

I use an organic fertilizer. (OK it’s boxed Dr. Earth, not a truckload from Natures Needs because it’s very convenient and my garden is small.)  I don’t know what my NPK ratio is which makes me a bit of a lazy gardener but the food I like to grow does fine.  NPK being Nitrogen, Potassium, Phosphorous.  And yes I was trained as an advanced master gardener and yes that was a very long time ago………they teach you all about soil in the master gardener program.

I wash my produce, no nibbling right out of the garden bed. (OK once in a while a strawberry or tomato).

According to some experts I’m doing OK but I could do a lot better.

My improvements

  1. Soil areas next to old garages often have higher lead levels.

    Soil areas next to old garages often have higher lead levels.

    Reducing exposure to dust is the most effective thing you can do to reduce lead hazard in your landscape. It is typically in the first few inches of soil. This is the most important thing in the blog.  Mulch and compost applications cover your soil and protect it from dust with contaminants in it.    We want to keep the dust and soil off human skin and out of the mouth.  This is critical for babies and small children and good for the rest of us too.  Adding compost has many benefits for improving conditions for plants.  Adding compost at least twice a year can only benefit, there are no drawbacks.

  1. Here at my community garden, we could have put a barrier between our new soil and the existing ground soil. I can still do this once my winter Kale are done in March. I’ll have to get a tarp and dig out a lot of my soil so I’m going to install a metal grid and landscape fabric.  The grid is to keep the moles and gophers out of my raised bed. They may have brought some of the lead contaminated soil up into my new clean soil, and they caused a lot of havoc with the roots of my plants.  Some died or did not produce well because of the soil disturbance.
  1. I could improve the efficacy of washing my veggies by using a 1 percent vinegar solution instead of only using water. I’m thinking a large spray bottle under the sink could be used for my final wash. It’s got to be simple or I won’t do it.

Beyond these good soil management practices, I will need to do a Nutrient Analysis soil test to know what I need to add to my raised beds to improve the health and productivity of my vegetables and bind up any lead and keep it locked into my soil where it won’t cause problems for me.

Portland landscape designer in edibles garden

My garden is below Highway 30. It’s an old heavily traveled highway so our soil has years of exposure to lead exhaust.

Lead Soil Test

My client Katy had an older home in SE Portland.  I suggested a lead soil test.  She collected the soil and submitted samples for a lead test. She discovered the area where we wanted the kids play structure to go had high lead.  It was next to the neighbors’ garage.  Several inches of contaminated soil were removed.  She brought in new soil and playground chips and now has a safe play area for her toddlers.

What’s one new thing you could do this year to improve your landscape or edibles garden?  Get your soil tested.  I’m planning to collect soil from my vegetable garden and submit it to a lab for testing.  I’ll share that experience with you in another blog.