Have you ever wondered what would happen if you ignored all of the crop rotation advice out there? The majority of advice on this subject suggests that my plants would immediately succumb to disease and leave me with record low yields! That sounds awful, but is it true? One crop rotation article I read concluded with the grower admitting she was simply too scared to ever try not rotating her crops, and it is this common fear that stops most of us from testing the rules and learning where the limits actually are. Well that fear stops here!
Crop rotation concerns can really flub up our planning process, so if we are going to bend over backwards each spring to accommodate a crop rotation regimen, I want to make sure those efforts are warranted. This season, I intentionally planted several crops in bed where the same crop had grown previously. Did my vegetables spontaneously combust? Let's find out.
Planting Broccoli After Broccoli
Crop rotation charts would tell you that you shouldn't plant any brassicas consecutively in the same space. The brassica family includes cauliflower, radishes, turnips, cabbage, Brussels sprouts, kohlrabi, and our crop in question, broccoli. That's quite few crops to rule out as possible successors every time I plant a brassica.
To put this brassica crop rotation expectation to the test, I deliberately planted two crops of broccoli in the same bed in the same season. The first crop of 8 broccoli plants was transplanted into the bed on May 8th and harvested by July 7th with a total yield of 6.4 kg. The plants were removed and one week later on July 16, the same bed was replanted with another round of broccoli seedlings. This time I only planted 6 plants in the same space because the first planting was a bit too tight, and these second heads were harvested on October 12th with a total yield of 4.5 kg. The overall yield dropped a little and the average head size dropped from 0.8kg per head to 0.75kg per head.
The same Gypsy broccoli variety was grown in the first and second planting, but admittedly, my sample size was very small here and there were no other fall planted broccoli beds with which I could compare yields. It's possible that all fall harvested broccoli would yield a little lower because brassicas are too happy being transplanted in the heat of summer? It's also possible that these numbers are showing us a decline in production because of this consecutive cropping. What's clear though is that the secondary planting of broccoli plants were healthy and we still had a good second crop oto harvest.
Planting Tomatoes After Tomatoes
Another act of planting that would be forbidden by any crop rotation chart would be to follow tomatoes with more tomatoes. Actually, it would be advised not to plant tomatoes after any crop in the solanaceae (nightshade) family and that list includes common crops like peppers, potatoes, and eggplants.
I put this nightshade crop rotation expectation to the test by planting the same crop of tomatoes in the same bed in two consecutive seasons. The tomato variety was Plum Regal tomatoes and they were grown in the HT.8 bed of our high tunnel. I used the same pruning and trellising routine for these plants each season. The only difference was the plant density. In 2022, the 20ft long bed was planted with 15 plants, but this proved to be a bit too dense, so and in 2023, the bed was planted with only 12 plants for more comfortable growth and management. Our 2022 Plum Regal tomato harvest totalled 111kg (244lbs) and our 2023 tomato harvest also totalled 111kg. I kid you not! In both cases, I would have left a few undeveloped green tomatoes on the plants so the absolute total production could have varied a bit in either season. The main point here is that there was no significant change. The plants were still healthy in 2023 and despite being planted at a slightly lower density, they still pumped out the same amount of tomatoes.
Planting Corn After Corn
No, you didn't! Yes we did. Corn is famous for being a heavy feeder that supposedly demands all the nitrogen it can get to be productive, leaving the soil depleted of nutrients and organic matter for the following season. Well, what happens if we plant corn in the same bed 2 years in a row? We took it one step further and planted corn in the same bed 3 years in a row, and this is what happened.
In 2021, we transplanted 60 plants of sweet corn into one of our standard sized field beds (bed F.5) on May 29. We harvested all of the cobs between August 6th and 20th for a total yield of 23.9 kg. The corn was removed from the bed and followed with a crop of fall spinach.
In 2022, we transplanted 60 plants of sweet corn into the same bed on May 27. The bed preparation and planting method was kept consistent by transplanting 2 week old seedlings through holes in landscape fabric just as we had done in 2021. Between August 10th and 22nd, we harvested 19.65kg of cobs.
In 2023, we started the season in the F.5 garden bed with an early crop of carrots, which were harvested on July 4th to make room for the corn. Again, 60 plants of sweet corn were planted in the same bed, but this time starting on July 4th, a month later than the previous seasons. The entire bed was harvested on September 16th with a total yield of 19.5 kg.
As a side note, we did also plant an early bed of sweet corn in 2023 on a different plot with the same standard bed size of 50 square feet. The total harvest from that bed was 20.3kg, which falls right in line with the harvests from our other corn beds in 2022 and 2023.
The harvest total that stands out among each of these crops is the larger 23.9 kg yield from 2021. I was curious about that higher number until I looked closer at my harvest log and noticed that in the first year, I had also harvested the smaller secondary cobs on the plants that were all underdeveloped. The weight of these non-edible cobs was included in the total and it shouldn't have been, but there's no way for me to go back in time and measure just the fully matured cobs. The following seasons, I just harvested the primary cobs from each plant and ignored the smaller secondary cobs when present. I think that's why the yields in 2022 and 2023 are more consistent.
To Rotate or Not to Rotate
So there are three case studies of crops NOT rotated with no apparent consequence. How can this be? Do we grow our vegetables on a disease free island? Is every grower who warns of crop rotation out to lunch? I will leave you to come to your own conclusions there, and if you want to dive deeper into the subject of crop rotation, I won't try to stop you. In fact, here's a 163 page crop rotation planning manual for organic growers to help get you started, but when you tire of sifting through all of that reading material, I'll still be here to tell you that growing vegetables can be simpler.
My conclusion at this point is that a strict crop rotation regimen is totally unwarranted. Yes, there are a few cases when we still rotate our crops intentionally and I explain those cases in this post, but otherwise, it would seem like our vegetable growing time and energy is better spent managing the variables that matter. To learn more about how we optimize plant growth, without stressing about crop rotation, head over to my Free Workshop.
