Vegetable Crop Rotation: How To Increase Your Harvests
Having problems with disease or pests? Are your vegetables not growing well? Learn how vegetable crop rotation every year can give you better harvests.
You’ve tried to grow food for your family but you’ve run into problems.
- you’ve had pests decimate your greens and leave you with leaves peppered with chew holes.
- you’ve had disease hit your crops and wipe them out every year like clockwork.
- you’ve had mediocre harvests and find that crops just don’t do that well anymore and you are having to use lots of fertilizer to try and get stuff to grow.
These problems all sound familiar as I’ve encountered all of them myself. And these problems are hard to avoid if you’re growing food organically without resorting to chemical pesticides, herbicides and fertilizers.
However by implementing vegetable crop rotation, you can help break the cycle of pest and disease infestations and depleted soil and have better and greater harvests.
Why Vegetable Crop Rotation is so Important
Insect pests are very territorial and love staying in one place. Once they have established in part of your garden, they settle in and raise their family there.
And then you get damage to your plants such as leaves with holes, broccoli and cauliflower heads filled with aphids and big fat cabbage worms.
And some pests can be very monotrophic – eating only one thing. So if you keep planting broccoli in the same spot every year, they are overjoyed not having to move to continue feeding on what they like.
The good thing is that pests hate it when you change their diet. They usually lay their eggs close to the best food source and so when you move their favourite food, they don’t know what to do. Yes, they could move but first they would have to find out where their food was moved to.
Without their favourite food source, the pests will die off. Maybe a few might find where you moved the crop to but you’ll find the infestations to be much smaller and easier to manage with organic pest control methods. Natural pest predators and beneficial insects will have an easier job of keeping the pests in check as well when there are less.
So vegetable crop rotation is great for confusing pests. You have to though keep it up otherwise pests will find the new location and settle in. You have to keep them guessing where their crop will end up next and they hate that.
Plant diseases can wipe out a whole crop. And they can be very persistent especially if they’re a soil-borne disease. Fungal diseases such as club root that affects brassicas can survive in the soil for years and affect every brassica crop you grow.
There may be ways to sterilize the soil between crops but unless you resort to chemicals, you will likely not be able to get rid of all remnants of the disease.
However as with pests, diseases require the host plant. Without the host plant the disease will die off. We’ve seen that in human history with plagues. Plague organisms will kill off a large number of the population but then run out of food (as morbid as that sounds) and die off.
So vegetable crop rotation will halt most soil-borne diseases or at least minimize them so that they can be handled more easily.
Soil gets depleted from every crop that is grown in it. Plants take up nutrients in the soil to feed themselves. You can and should add amendments and fertilizer to boost soil health, especially before you plant out transplants or direct seed.
However for the best soil, building the soil by following vegetable crop rotation is the best method and will save you money on purchasing all of those amendments and fertilizers.
One key element is nitrogen. Legumes such as beans and peas help to fix nitrogen in the soil. They are able to extract the naturally occurring nitrogen in the air and store it in their roots. When the plant is spent at the end of the growing season, it then releases the nitrogen into the soil where it is available for the next crop.
The other way that crop rotation will boost your soil health is by growing root crops to break up heavy soils. No-till gardening is becoming popular so having a natural way for your crops to loosen the soil for you naturally is a great benefit.
Growing potatoes has always traditionally been a great way to prepare the soil for other crops such as greens that require a loose soil. However potatoes are notorious for having diseases such as blight that can affect crops planted afterwards. They are better grown in grow bags which can be emptied at the end of the harvest and new soil used for the following crop of potatoes.
Root crops that are especially good at loosening soil include parsnips and carrots, but even the daikon radish does a good job with its roots.
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How to handle vegetable crop rotation in different growing areas
How you actually rotate your crops will depend on where you are growing your vegetables. Each area has different considerations. Pick the one or more that apply to you.
Raised beds probably are the easiest to practice vegetable crop rotation in. You have pre-defined spaces, often they are all the same size and likely you have several beds.
A 4’x8’ bed can be split in two so that you have 4’x4’ beds you rotate through. I have two beds that are 4×12, so I could split these up into 4×8 and 4×4 beds or even two 4×6 beds. The two other beds are L-shaped, so I have two 4×8 beds if I split up the L. You do have to be careful as your crops are closer together that in separate beds.
One tricky thing is if you have trellises installed for growing vegetables vertically. There are two ways to deal with that:
- Make the trellises removable and movable to any bed that needs them.
- Put up trellises in all the beds where you’ll need them. Some crops won’t need them, so they will be unused one year until you rotate crops in that need them. Make sure trellises don’t shade other raised beds.
Square foot gardening beds
Square foot gardening has become very popular after the publication of the book Square Foot Gardening by Mel Bartholomew. It lets you grow a variety of vegetables in a small space using intensive gardening methods.
You can use vegetable crop rotation even with square foot gardening. If you have enough 4×4 beds you would simply grow each food family in a different bed following the regular crop rotation cycle. If you don’t have enough beds, you could treat each foot or metre square and rotate among those but you don’t get the benefit of separating crops far enough apart.
In ground beds are a bit trickier. Often these beds are much larger and plants typically are grown in rows. And there is not the distinct division as you have with raised beds.
Find a way to divide up the in ground beds into manageable sections about the same size as a raised bed would be. Use dividers that you can move. Untreated railroad ties or straight branches work. Or use bricks or pavers to divide up the space.
Or if you think your sections will not change, establish permanent pathways between the beds. Strips of lawn the width of your lawnmower work or you can use wood chips or gravel if you have a way to contain the material to the paths.
Containers are a bit easier to manage. Pests won’t find their way to your containers if they are soil dwellers nor will disease spread as easily from other areas of the garden. You can more easily amend the soil as there is less of it.
But where you can, it helps to still rotate either the crops or the soil.
For small planters or where you only have one it’s best to actually rotate the soil, not the crops. One easy way is to remove spent plants and then dump the soil into your compost. Clean the container well and then add new soil, amend it with your favourite organic fertilizer and then replant either with the same plant or a different one.
For larger planters that are harder to empty, rotate your crops like you would in a raised bed or the ground. Obviously you would need enough containers to be able to rotate everything. And if you can, it’s best to keep the containers with one family of vegetables physically separate from others in another part of your garden.
You may also find that you’re growing more than one family of plants in the same container, like with my daughter’s garden planter box. For any problems you get, you’ll have to replace the soil unfortunately.
In the greenhouse, vegetable crop rotation is key. This is the perfect place for plant diseases and pest infestations simply because plants tend to be closer together.
You also don’t have the wind moving through drying off leaves to avoid mildew. A pest colony can establish quickly without some of their natural predators present.
You can use the tips above depending on how you’re growing vegetables in the greenhouse. In a greenhouse it is more common to remove soil and replace it with clean soil where you can.
And in addition to rotating crops to avoid disease and pest infestations it is also important to keep the greenhouse clean.
How to Plan for Cover Crops
Cover crops are very beneficial to your soil and help build the soil without resorting to buying chemical or organic fertilizers. You grow a cover crop like winter field peas, till it under and it helps feed the next crops.
Year-round cover crop
When you have the space and enough raised beds or enough in ground beds, you can afford to take a whole bed or two out of the active growing cycle and grow a cover crop to build the soil to replenish it.
Some cover crops do take longer to grow so having the extra time for them without having to accommodate a regular food crop is the best way to go about it.
Adding the cover crop to the regular crop rotation can be done by replacing an existing crop (usually legumes) or by adding another year to the crop rotation.
Seasonal cover crop
When you don’t have the luxury of lots of beds, taking a whole bed out of production is hard to justify. You still want to build soil but not lose the ability to also feed your family.
So you need to consider planting a seasonal cover crop. You should still rotate your crops as usual but plant the cover crop right after a warm season crop such as summer squash or tomatoes is harvested. You may need to use row covers to allow the cover crop to grow before the weather gets too cold.
In spring then you would turn the cover crop under, wait a few weeks for it to break down in the soil and then plant your next crop following the regular corp rotation sequence.
Planning for vegetable crop rotation takes a bit more work and time. However the benefits outweigh the extra work, especially when you have better harvests. Give it a try next growing season!