How Does Planting A Diverse Garden (Creating Biodiversity) Help With Pest Control?
The magic is in the details
Perhaps one of the most frustrating thing for gardeners is discovering that all your hard work is being gobbled up by something other than you, even before it is ready. Caterpillars, beetles, weevils, aphids, mites, whiteflies, slugs, snails . . . the list of critters that want to eat your veggies is very very long.
And since we live in an instant world, most of us at one point or another start Googling for the fast fix to our pest problems. Surely there is a way to make the eaters go away now! But at what long term and environmental cost?
Pesticides create serious long term impacts to our gardens, soils, food and health. These toxic-by-design chemicals don’t belong in your food supply.
But what if I told you the real fix is to not attract those buggers in the first place?
Creating biodiversity in your garden is the magic step to minimizing your pest problem without any additional work at all. You are already planting a garden. Now is the time to design that garden to minimize pests.
Let’s take a look at how creating garden biodiversity can prevent many pest problems before they even begin and help to keep the rest of the pests manageable.
Pest reduction strategies using garden biodiversity:
1) Companion planting
The most common strategy touted in garden circles for reducing pests is companion planting. Companion planting is when you grow specific plants side-by-side to produce beneficial results like pest control.
Common companion planting recommendations include:
Marigolds planted with tomatoes can repel soil nematodes
Nasturtiums can attract cabbage worms away from brassica plants and thus reduce damage on the vegetables
Dill attracts aphids away from other plants AND attracts ladybugs that will eat the aphids
Basil can repel potato beetles off tomatoes and peppers
While companion planting has a long history and lots of folklore, the reality is that including different types of flowers and strong scented herbs in your garden works on a broader basis than simply putting one plant beside another expecting a specific result. Keep reading for more details.
2) Add flowers
The fastest way to reduce your pest problems in your garden is to add flowers.
Flowers have three key roles in pest reduction:
They attract insect predators which act like your own pest eliminating army, working tirelessly to eat up the pests in your garden every day.
Many flowers also have strong scented foliage which can deter pests. Most of the herbs fall into this category – think basil, thyme, rosemary, sage, dill, borage and many more. Both the flowers and the foliage are involved in pest management.
Some flowers actually attract the pests, diverting them off your vegetables (this is also known as a trap crop).
I am sure you can see the overlaps here with the concept of companion planting. And it is no surprise that the companion plants tend to be flowers and herbs! It’s just that the lore of companion planting is more limiting than simply using flowers throughout your garden to minimize pests.
Try a flower border, or maximize flower values by interspersing flowers throughout your garden. You can level-this idea up one further if you can establish some perennial flower patches that will provide all season habitat for your the pest predators.
3) Mix your vegetables
Mixed vegetables don’t just look good on your dinner plate, they belong mixed out in the garden as well.
There are still a lot of images out on the internet of vegetables planted single file in long rows. One type of vegetable to a row, and one type of vegetable to a large block of rows.
Newer images promoting raised beds do .a better job of promoting mixed plantings within the bed.
The important point here is to avoid row and monoculture dogma that is the hallmark of large commercial farms, which spray tons of pesticides every year. That doesn’t have to be you.
Even if you want to plant dozens of tomatoes or broccoli or potatoes, the best strategy is to mix your vegetables in your garden design. The two easiest ways to do this are:
Take your most abundant vegetable and plant it down the middle of your wide row and then plant the rest of the space with many other vegetables and flowers.
Take the total number of individual plants you want to grow of each type of vegetable, and disperse them as squares or blocks throughout the garden.
Both strategies lead to similar results: no monocultures. Small groupings one type of vegetable, intermixed with blocks of other unrelated vegetables and flowers, creates the most difficult scenario for pests. They have to navigate further to find more suitable hosts. They might find one patch, but not another.
Compare that to long rows and monocultures of all the same plant. The pest insect has no trouble finding more and more hosts to feed on.
Small interspersed blocks are less attractive to pests and harder to find.
4) Create Biodiversity
So the best strategy in my opinion is to combine all of these ideas into one garden. Companion plant where that makes sense. Divide up your total vegetable plants of each type and spread them all across your garden, trying to keep similar varieties apart. And then, intersperse flowers in the same way you have the vegetables, ideally in patches, borders and ground covers all over the garden.
One way I like to do this is by thinking about which herbs belong in a recipe together. Tomato sauce needs oregano and basil. Pickles need cucumbers, dill and hot peppers. Salads should be more than just lettuce for good health. Therefore your salad rows need mixed greens which can include lettuce, arugula, kale, spinach, radish and mustard greens which combined make a much better garden bed (and salad!) than lettuce alone.
Garden biodiversity is the fastest mechanism to minimize pests and it requires no additional work from you other than a shift in how you plant your beds. It’s hard to get any easier than that.
Take the bite out of pest control
There is one further strategy you can apply for natural pest control, but it won’t work for everyone: Ducks and chickens!
Birds love bugs! Bugs are great protein and lead to richer eggs. (and please note there is no such thing as vegetarian chickens! Birds eat bugs and worms all the time, and some will happily eat rodents and small snakes and even frogs).
Domestic birds do a great job at killing off garden and orchard pests. Chickens like to scratch up the soil and uncover lots of insects hiding there. They also do a great job at eating the fallen fruit in orchards which can really allow some pests to multiply.
Ducks will hunt bugs all day long. They also like to drill down into the soil after grubs and pupae.
But there is a downside to chicken and duck pest control . . . they eat the good guys too, just as often as they eat the bad. That means spiders, worms, beneficial parasitic wasps, aphid eating syrphid flies, and voracious ground beetles get eaten up by ducks and chickens too.
I find it most useful to have the birds as the garden perimeter guard and limit their access to the interior workings of the garden during the growing season. And in the orchard, I prefer running ducks who don’t scratch up all the ground covers. But ducks don’t eat the fallen unripe fruit, so having a small flock of chickens mixed in seems the best orchard strategy.
Again, not everyone is in a position to have birds for pest control, but if you are this is a big win for pest control, and you get the added bonus of eggs for breakfast.
Gardening without pesticides is easy to do
Contrary to pesticide advertisements, it is actually possible to successfully grow food without added pesticides. Creating garden biodiversity is the key to making it easy.
But what happens when the pests are taking over anyway, despite your efforts?
The most useful pest clean-up strategies include:
Using water or soapy water to dislodge and remove the insects from your plants.
Hand-picking caterpillars, potato beetle grubs and other large pests and drowning them in a bucket of soapy water. You can also feed them to your chickens or ducks if you have some.
Cover an infested plant tightly with row cover cloth or similar material to prevent the insects from spreading. This is a stop-gap measure that buys you some time to figure out disposal, while also letting your remaining plants grow without lateral spread of the insects.
Cut off the infested plant parts or remove the whole plant and place it - bugs and all - in a black plastic bag. Seal the bag tightly and leave it in the hot sun for about 4 days (longer if temperatures are not very high or if you only have part sun). This will heat-kill everything in the bag. Then it is safe to add the contents to your compost pile or dig the material back into the garden somewhere. (Note that just throwing pest-filled plants into a compost is rarely fast enough to stop the insects from dispersing - not to mention that carrying infested plants through the garden is likely to just spread the bugs everywhere).
I have been using these gardening methods for years and overall my insect problems are very low. It is important to realize that sometimes, for one reason or another, pest populations may be high in your area for a given year. For example, a mild winter may mean more insects have survived the winter and are now ready to eat and reproduce. Or a dry warm spring may lead to more grasshoppers.
While you cannot control the weather or these insect cycles, creating garden biodiversity can provide the best possible habitat for your army of beneficial helpers. And not spraying any pesticides at all is the best possible way to keep your garden, soil and yourself safe from toxic chemicals.
Happy gardening, and happy eating.
Great advice Sue - just as I was trying to get re-motivated with the spring planting! :)