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.

Herbs

• 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.

Vegetables

• 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?