Monday, September 27, 2010

One year of slug experience - what works, and what doesn't, at least in my garden (including lists of slug resistant plants)

I wrote a post on slugs last year after planting lupins as green manure and watching them get devoured overnight by slugs. This inspired me to do some research on slug management, the result of which was I didn't want to use slug pellets and also didn't want to ruin my karma by constantly slaughtering the creatures. I also found some great books and websites on the subject of slug-resistant plants.

So where am I a year later? First off, we have a really bad slug problem. Our garden is on the edge of a Rhine flood plain and large nature reserve on the one side, and on the other are dozens of other allotments in our garden colony. It truly seemed like a hopeless battle. My main strategy was to plant only slug-resistant flowers and vegetables. After consulting many sources, here are my lists with my personal experience.

  • chives
  • garlic chives
  • lavender
  • lemon balm
  • lemon thyme
  • lovage
  • oregano
  • peppermint 
  • rosemary
  • stevia
  • St.-Johns-wort
  • thyme 
  • valerian
    These all worked pretty well and were mostly avoided by slugs. Exceptions: the stevia was almost annihilated, and the lemon thyme (Thymus citriodorus) was devoured overnight. The peppermint was attacked but survived, but I planted some on our roof deck just to be sure. The stevia I managed to save by putting a snail collar on it - see below, but I gave up on the lemon thyme. Didn't even try parsley or sage.
    • cucumbers
    • garlic
    • lamb's lettuce
    • leaf lettuce
    • leeks
    • onions
    • rocket
    • tomatoes
    • zucchini - I raised the plants from seeds indoors until they were quite large.
    The only one of these that was notably attacked were the cucumbers, which were also fine after I put a snail collar on them. Here, too, there were many things I didn't dare try, like cabbage, broccoli, kohlrabi, etc.

    Perennials - negative list
    I inherited many perennials from my predecessors in the allotment, but also planted some myself. Here are some that were incessantly attacked by slugs to the point that they just looked terrible, despite the fact that some of them are listed by some sources as being slug-resistant:
    • all of the at least five types of hostas I had
    • Centaurea montana (perennial cornflowers)
    • salvia of various kinds
    • lobelia of various kinds
    • Echinacea of various kinds (coneflowers)
    • marguerites
    • hydrangeas
    • asters
    • clematis
    Although these flowers survived and even bloomed, I've now thrown them almost all out because I can't bear the way they look after slug attacks.

    Perennials - positive list
    These flowers weren't touched by slugs:
    • dame's rocket (Hesperis matronalis)
    • forget-me-not (Myosotis)
    • hellebore
    • hardy geraniums
    • astilbe
    • lady's mantle
    • roses
    • bleeding heart (Lamprocapnos spectabilis)
    • columbine (Aquilegia)
    • day lilies
    • irises
    • common bugle (Ajuga reptans)
    • alum root (Heuchera micrantha)
    • saxifraga of various kinds
    • sedum of various kinds
    Annuals - negative list
    • violas - forget it!
    • petunias - I planted some in hanging baskets two meters off the ground and still found slugs in them, god knows how they got there.
    • lantana - Wouldn't you think that these prickly, strong-smelling plants would repel slugs - hah!
    • sunflowers - By installing snail collars until they were about a meter high I managed to raise amazing sunflowers, but they are definitely beloved of slugs when young.
    •  zinnias - Gave up and had them only on the roof deck, where they did beautifully:

    Annuals - positive list
    These flowers weren't touched by slugs:
    • moss roses (Portulaca grandiflora)
    • pelargonium geraniums
    • impatiens (Impatiens neuguinea)
    • nasturtium (Tropaeolum majus)
    I also purchased a seed mixture of annuals resistant to slugs called (in German) "Sperli's Schleich Dich Blühende Schneckenbarriere".
    This was a fabulous buy and produced many lovely flowers that were not touched by the slugs. Unfortunately, the package does not list what kinds of seeds it contains. I identified the following:
    • love-in-a-mist (Nigella damascena), both blue and white
    • some kind of rudbeckia
    • some kind of snapdragon
    I've already purchased another package for next year. Maybe someone can identify the flowers in this mixture more precisely? In the first shot below are what I think are some kind of annual rudbeckia, and in the second shot you can see the lovely seed pods of love-in-the-mist below the rudbeckia, and in the background you can make out the pale blue of still blooming love-in-the-mist. In the lower part of the photo is what I believe to be snapdragons (click to enlarge).
    I tried a few other methods of discouraging or getting rid of slugs, and found the following to be ineffective: coffee grounds, watering with moss brew, and beer traps. I also broke down and tried environmentally-friendly ferramol snail pellets. Both beer traps and pellets killed a few, but they were followed immediately by legions more. The only manual method that made a difference was simply gathering them up by the dozens (or hundreds!) at dusk and killing them, not a fun activity.
    So my resume: 1) Be more consistent about only growing slug-resistant plants, and 2) snail collars work on plants with the right shape and size.

    How about the rest of you?

      Thursday, September 23, 2010

      New Christo and Jeanne-Claude project - in my garden

      When I got to the garden one day last week here's the scene I found:
      A large part of the garden had been covered with various tarps and fibrous sheets. What was going on? Well of course we knew that it wasn't really Christo and Jeanne-Claude.

      A power line runs through the forest just behind our allotment, and one of the power towers is just off our back border. The city recently began renovating the towers, i.e. cleaning, sanding, and repainting them, for the first time in almost 50 years as my garden neighbors reported. The first ominous sign that our tower was also up for maintenance was the removal of all trees, shrubs, and underbrush within meters of the tower. Before they did this, it looked like this:
      There was such dense growth around the tower behind our fence that we enjoyed a lot of privacy from the hiking, riding, and dog areas beyond the allotment. The clearing now made it seem open and exposed. So we'll be putting up willow screening until things grow back.

      But what I was really worried about was possible damage to the garden. I'd already watched them working on the next tower down, further away from the allotments. It had looked like they were sand-blasting, causing large clouds of debris and hours of noise. But as I was standing dismayed in the garden surveying the number of trees and shrubs that had been removed just outside of our lot, the foreman of the maintenance crew approached and explained that they would do all they could to not damage the garden, including covering everything with protective sheets and tarps, and that the workers would all use umbrellas to catch falling debris. Also, in our case they would forgo sand-blasting, instead scraping the decades of moss and dirt off by hand.

      And indeed that's what they did. Here they are working on the tower with upside-down umbrellas:
      And here a view of some of the workers on their way up:
      I'm very grateful to the whole crew for taking such care. It seems they know that gardens are the apples of their owners' eyes. The only damage done were a few bent rose blossoms. And the tower should be good for another 50 years now!