The Wasp, the Slug and the Fava Bean

IMG_2029I haven’t been writing much this season. Honestly, I have been more often frustrated than not with the garden. This season started so promising. Rye and wheat exploded and filled winter beds with greenery, the green houses were filled with plugs of plants grown to schedule and my over-wintered cauliflower produced heads before most things were even planted. However, I should have seen the warning signs: slugs were all over the cauliflower. All three plantings of brassicas since then seemed to evaporate with slug pressure – give kale a few days and there was literally nothing of it. 

So first, THE SLUG. I know this is a problem for many. When I speak for garden tours or gardening groups I am always asked what I can provide for slug control. I tell them what I have been told, but I have until now had no practical experience. Now, I have tried it all.

My wife placed copper tape along all of the beds in hopes of preventing new slugs from entering. We dug holes, placed cups and filled them with beer. I spend time every few days physically removing slugs, but most were tiny and this was tedious.

Has all this worked? The beer certainly did attract and drown slugs. But there was often more slugs on the plants adjacent to the beer trap as in the beer trap. There is no verdict on the tape. I think slug pressure is naturally declining, so it is too late to tell. The physical removal MUST help, but may not be sustainable….I get bored easily. 

What I have learned and want to share are these changes I will make for next year: 

1.) I will only over-winter brassicas in the previous years’ bed, so any brassica pests will be lessened in beds receiving the spring plantings. 

2.) I will begin beer trapping weeks before the first spring plantings. With no plants (or no attractive plants) present, the beer should be irresistible. 

3.) I will use copper tape before spring plantings so, if it works, slugs will not enter the bed from that point forward. 

4.) In the most slug-sensitive crops I will plant sacrificial mustard mesclun. This crop was a favourite for slugs and one of the crops I was looking forward to eating the most. I bought from West Coast Seeds this mix of 5 mustards (for mustard greens): Mizuna, red komatsuna, Giant Red Mustard, and two types of pac choi. I will start these indoors in a flats as early as week 1 and use them to “mop up” the slugs. I’ll throw the infested plant in the compost, or shake the slugs off to feed the gold fish in my pond. 

5.) I will remove all over-wintered mulch before plantings. I have learned this may be the hiding places for slugs. (I had used straw).

To give you an idea of the slug problem: I have grown one zucchini from 6 large healthy plants – I have to remove slugs from the flowers nightly. My giant yellow corn (which grew over 18 feet last year) suffered, and having too few kernels to replant, I am left with two or three plants I can only hope will produce a cob or two to reseed with next year.


I replanted my kale 5 times! The last time I left them in 4” pots until they were almost 8” high. They have survived, but have not grown, and a few are mostly “skeletons.” My wife’s flower garden is bare. I can’t be sure this is slug, but it seems likely. I just planted cilantro for the 5th time as well. I stuck established plugs, but moved a few “back-ups” into 4” pots that I’ll hold for a few more weeks. I have even direct sown twice with none getting higher than half an inch. Chard is non-existent as is arugula. 

Fortunately, my lettuce and spinach seem to outgrow the assault, and harvest has been steady. The snap peas I put in early and they have only begun growing quickly as of mid-may. Now, they seems to have no problem outgrowing the slug damage. 


(The yard last year – note the size of the corn on the left – taken June 6th 2019)


(Photo from June 3, 2020 – Note corn is in the back, furthest bed you can see. And chickpeas are the bed to its right. The chickpeas were front left in the photo from last year.)

THE WASP. There is a lot of attention on wasps here in the Pacific North West. With an actual sighting of the Giant Asian Hornet in Washington, people are on high alert. I had one in my amaranth last year, and reported it. Be on the look out!

The real reason I bring up the wasp, however, is because I joined a gardening group on Facebook in hopes of having some questions answered and have since stopped paying attention to the group as it is bombarded daily with requests to ID simple plants and wasps…always wasps. What shocks me, is no one is posting pictures of tiny aphidius wasps or anything interesting, it’s all yellow-jacket and paper-wasps which I assumed everyone could identify. Then the comments are all about how to kill them. So, as a public service announcement, I want to remind everyone that those wasps (and pretty much all of them at this time of year) are some of the best predatory insects for your yard. They might get mean in the summer, but right now, just leave them alone. Here on the West Coast we are having the second consecutive year of a nasty infestation of caterpillars (likely the Winter Moth), and wasps of the large size are one of their main predators. To my knowledge, only the Giant Asian Hornet, is not an incredible beneficial insect here on the West Coast of Canada. 

FAVA BEANS. Ok, this is only partially about the bean. It’s mostly about over-winter crops. I did some basic research about what to grow over the winter. The benefits of winter crops include:

1.) soil retention – not sure where the soil goes, unless you’re on a steep hill, but I can guess that without roots, heavy rainfall can cause compaction of the soil.

2.) Leaching. Nutrients are dissolved in the rain and washed through the soil and carried away.

3.) Habitat. This can be habitat for pests, but also beneficial insects. The key here is crop rotation.

4.) Fixing nutrients. Crops like Cereal Rye (not to be confused with ryegrass) and beets can send roots as deep as 20 feet, effectively bringing nutrients to the surface for shallow rooted plants, and loosening soil throughout that full column. Legumes have a symbiotic bacteria that fixes nitrogen to their root nodes. They can, therefore fix nitrogen into the soil. However, because the actual bean is high in nitrogen, I figure that legumes only fix nitrogen if tilled back into the ground of killed before fruiting. 

5.) Seasonal harvests. Planting the right crops in the right places may allow for a winter harvest. 

6.) provide plant matter to “till-under” ahead of successive crops. 

However, here are some problems:

I grew Rye and Winter Wheat. I planted it in September and read that the harvest would be “early the following year.” I have yet to harvest and have taken most of the crops out to make way for summer plantings. For example, rye was planted and expected to be harvested by May to make way for tomatoes. I cut the immature rye and planted the tomatoes. This is fine as a winter crop, except that I was under the impression I’d be harvesting grains. Likewise, the winter wheat is close to finishing, but I have pulled most of it to make way for tomatillos and cherry tomatoes. I am waiting for the rest of the wheat to finish so I can plant my peppers. I also had to remove rye from another bed to place all my squash. So what I had hopped was a winter/spring crop to be followed by warm summer crops (tomatoes/tomatillos/peppers and squash). Instead, I got a winter/spring crop that should simply have been tilled-under. But I don’t till. 


(The wheat is beautiful, so I didn’t haul it all out. Instead, just made some room. Here are tomatillos grown along the south side of the wheat.)

I grew fava beans to provide plant material, winter flowers, nitrogen fixing and food. What I got was very, very slow fall and winter growth (so plant material and cover of soil was minimal) and no flowers until mid spring and only now, first week of June, do I see pods big enough to consider harvesting. So again, my hopes of a winter/spring crop taken to harvest and followed up with a late spring or summer crop didn’t materialize. 

Also, I mentioned the suspicion that beans only fix nitrogen before fruiting, since the fruit contains so much nitrogen (mostly as protein). So, I did some research, and it turns out to be true. The nitrogen creation in the full life cycle of a legume if the fruit is harvested is essentially neutral. So it fixes nitrogen, and then uses it to produce fruit. Only tilling in before fruiting results in added nitrogen to the soil. This illustrates a pet-peeve I have for the internet – incomplete truths. All over the place people mention legumes as nitrogen fixers; Did no one know or did not one understand that the availability of that nitrogen for other plants is limited in time to only a few early weeks. Likewise, in hearing winter wheat is planted in September and harvested in “late Spring” actually means: While you plant it 6 months earlier, you only harvest it a few weeks earlier than a spring planting. (Although yields are often greater). Which essentially means my winter wheat will be harvested mid-summer. Beware these half truths. 

I mentioned the success of over-wintering cauliflower. However, I overwintered all brassicas. Following successful spring and late summer harvests, I replanted the crops a third time: Broccoli, brussels and left the Kale, and left the cauliflower, which hadn’t matured yet. Come March I had beautiful cauliflower and good growth on the others. A few weeks later all others bolted. Broccoli didn’t form a crown but shot-up like weak-looking broccolini. Even the Kale that I figured could be kept as a perennial produced long flower stems from each leaf stem. It was certainly a waste of a winter crop. 

(2019 broccoli [left] vs 2020 broccoli – both photos first week of June)

I have to entirely rethink my rotations. In a nutshell, my crops that need hot weather were to be preceded by the long-season cereal grains. The mid-late spring planted crops were to be preceded with the earlier fava bean crop, and so the rest of the beds were to be planted with very early crops, and would therefore receive no winter crop ahead of it. I will try the cereal grains again, but in beds that will allow them to go to harvest. So, it is no longer a cover crop, but just a long crop. I will do the fava beans again either sparsely as I did, and interplanted with spring/summer crops or more densely ahead of a summer direct sow crop – maybe corn (which I will plant later next year) or black/kidney beans…although I’m pretty sure you can’t successively plant legumes. I will try the brassicas again with different planting schedules ore with cauliflower dominating the crop. And it will not be in the bed ahead of spring brassica plantings, but ahead of the next crop in rotation. 

Other crops I am still deciding how to use are Buckwheat and Yellow Mustard. Buckwheat is fantastic for attracting beneficial insects and is incredibly fast growing. It is usually used to till-under. I let some seed last year and it reseeded itself, so I will be more careful. The yellow mustard was supposed to be a true over-winter crop, but is showing the same growth behaviour with those planted last fall and those planted early this spring. The flowers are beautiful and also attract all sorts of insects – I consider it a must-have in the garden. 


(Mustard is a beautiful crop)

It may be back to the drawing board for how I rotate the crops, however.

In other news, I waited for my strawberries to start ripening, which is a celebratory time for my kids in the garden. One morning, knowing they’d be ripe, I walked about before the kids woke and found almost ever strawberry half-eaten. They were literally half-eaten, from the tip back. Quickly considering culprits, I suspected first my dogs, and then the European Wall Lizards that are unsettlingly numerous.  However, this morning I saw a rabbit leaving my yard and suspect this could be the problem. I am surprised however that lettuces and other crops do not have what might be rabbit damage. But, the strawberries are one of the boxes dug deepest into the ground and thus have the lowest walls. 

Also, all my stone fruit are eaten. Now, I suspect birds or again the lizards (which according to the internet, eat insects and fruit). There are few cherries in tact. Both nectarines and peaches are all eaten, but not entirely eaten. Just like the strawberries, they look like bites were taken out of them. It’s all heart-breaking.


In general, I believe my yard simply needs to find an equilibrium. I took out a lot of bush and trees to make my gardens. Now, there are fewer birds, and probably fewer predators in general. The good thing about high slug populations, is if left, the natural predators will have a good year (too late for my veggies, though.) Then next year there may be more slug parasitoids, more birds, more spiders…etc. 

Let’s hope so, anyways. 

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