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10 Lessons From the Vegetable Garden: Part 3

Updated: Dec 23, 2023

One of the pleasures of growing your own food is that there is always more to learn, so we're back with our annual round up of new lessons learned from the latest growing season. There's not really a definite way to rank these lessons because they are all important, but I've generally put the simpler lessons near the bottom at number 10 and the more complex or impactful lessons closer to number 1 on the list. If you missed parts 1 and 2 of this series from previous seasons, check them out here: Part 1, Part 2.

Lesson # 10 - Debunking a Fear of Clay

I often come across negative remarks about growing in soil with a high percentage of clay, and one extreme example of this was hearing another grower say that potatoes don't grow well in clay because the soil is so stiff that it doesn't allow the tubers to swell up. What?! The best way to debunk a myth like this is to let the results speak for themselves, so this season I planted all of our potatoes on our garden site with heavy clay soil, and even in part shade.

The potato beds at our clay plot are shown in the photo above. I planted 6 beds or a total of 300 square feet with 3 different varieties. One of these varieties was Purple Viking, which is known for producing tubers of a large size so if clay soil actually causes potatoes to flounder, the Purple Vikings should really have trouble here.

The plants looked healthy throughout the growing season and when it came time to harvest there were no real surprises for me either. Despite the stiff physical qualities of clay soil, the tubers had still managed to make their own space and swelled up to sizes that were expected as shown by the photos below.

potatoes under the soil
Note the presence of big tubers in the soil despite the high clay composition.
potato harvest
Here's a look at the average harvest from one Purple Viking plant in clay soil.

The average yield of 1 Purple Viking plant was 4.5 lbs when planted 12 inches apart for a total yield of 41 kg or 90 lbs in each 50 square foot bed. This is on par with other similar varieties we have grown on our sandier plots in past seasons, so there was no disappointment here.

If given the choice, I would still elect to grow root crops in sandier soil because the harvesting is a little easier, but clay has two very favourable characteristics for growing. The first is that clay particles expand when wet helping to prevent water from quickly draining past the roots. The other is that clay particles are negatively charged which allows them to cling to the many positively charged nutrients in the soil such as calcium and magnesium. In the rather dry growing conditions we have here on the Canadian prairies, that water and nutrient holding capacity is really valuable.

Lesson #9 - Hydrophobic Compost

A lot of our growing lessons are planned, but this one came as an unwelcome surprise. After finishing all of our bed preparation at one particular plot, we planted our first crops only to discover that the compost we had used to top our beds did not absorb water! It is our standard practice to coat the tops of our beds with compost to enrich the soil and serve as a weed barrier while minimizing tilling. That approach had always worked well until now. As outdoor growers, we really count on water being able to penetrate through the soil to the roots of the plants, so this hydrophobic compost presented a life threatening challenge, one that we really hadn't faced before.

Closer inspection of the compost revealed that it wasn't fully decomposed. Our source for this load was our city's compost depot where the predominant source of organic matter seems to be tree prunings from the city's maintenance crew. They do grind up the wood before composting it with grass clippings and other donated organic matter that is available, but the end product in this case was still so woody that it seemed more like peat moss than finished compost. Water falling on the surface would gather in puddles and roll off the beds into the pathways.

After several frustrating attempts at hand watering and digging holes through the top layer of compost, I gave up and pulled our rototiller out of retirement to mix the hydrophobic compost with the garden soil below. Thankfully, I hadn't planted all of the beds at this plot yet and could still churn up the empty areas quickly. This made a world of difference with the water absorption but it didn't end the troubles. Production in these beds was hindered by the mixing of this unfinished compost because the initial decomposition of this raw organic matter steals available nitrogen from the soil leaving less for the plants. Two good indicator crops for this were celery and squash which were noticeable paler in colour than usual. The tilling also brought up a ton of dormant weed seeds to the surface so the carrot beds you can see in the photo below required a lot of extra weed management time this season.

Carrot beds in vegetable garden.
The carrot beds in the foreground required a lot more weeding time this season after an experience with some hydrophobic compost.

The lesson here is that you get what you pay for. Our city sells its compost for $15/yard while an independent compost supplier in our city sells their product for $50/yard. The economic appeal of the city's product is undeniable, but after an experience like this, I'll be sticking to my primary supplier. For those of you in our area, we use Deptuck's Landscaping. They make all of their own compost and the owner Lawrence has really got his process nailed down to produce a consistent product that performs well.

Lesson #8 - Rogue Peas Spoil the Party

Over the last few years, we've fallen in love with snap peas, and in particular the Super Sugar Snap variety that produces crisp plump pods often exceeding 3 inches in length. This is a hybrid variety that grows to 5 or 6 feet so most peas are picked at chest height and that makes harvesting is a real treat.

The harvest wasn't such a treat this year though as we discovered that we had received a bad batch of seed. About 50% of our seed produced alternative pods of some kind. Some resembled the thinner snow pea varieties and others had stringy pods more like a typical shelling pea. What made the matter worse, is that it was pretty hard to distinguish the different peas before biting into them. I did my best to sort through them for the first few pickings but eventually decided it was in my best interest to pull the crop entirely.

Early removal of contaminated pea crop to allow more light into squash patch.

This kind of problem has nothing to do with how we planted or tended to our peas. The seed variation is caused by a lack of care during the breeding process. A quality breeder will take the time to remove rogue pea varieties from their seed production fields in order to maintain a consistent end product. Somehow, errors were made with this particular batch of Super Sugar Snap Peas. We bought this seed from T & T Seeds so I called them to report this problem. They confirmed that others had reported similar results from this particular seed and offered store credit equal to the value of the bad pea seed they sold to me. However, this did little to compensate for my wasted time, the cost of the growing space, and hundreds of dollars of lost income.

The lesson I was reminded of here is to buy our seed from as close to the breeder as possible. I like to support T & T Seeds because they are a Canadian seed dealer close to us on the prairies, but they are merely dealing seeds as opposed to breeding their own seeds to sell. When we buy our seed from breeders like Johnny's Selected Seeds or High Mowing Organic Seeds, we are much less likely to have this kind of problem. For more information about the care required to maintain seed quality see this post about pea selection at Johnny's.

Lesson #7 - Seasonal Light Changes

At the Earth's equator, day length and light intensity remain consistent throughout the year but those of us growing far from the equator will experience significant changes with the seasons. Those of us in northern areas will experience much longer and brighter days during the summer and much shorter and dimmer days during the winter. This change in light availability really impacts the rate of growth in our gardens. Since I talk about season extension quite a bit, I often get asked why we don't continue growing throughout the winter, and light availability is one of the major reasons.

Our human eyes are terrible at judging light intensity because our pupils constantly contract and dilate to adjust to the light around us. A sunny winter day seems bright to us, but it still doesn't compare to a sunny summer day, when the Sun is so much higher in the sky and the sunlight is passing through much less of our atmosphere. I thought a graph or two might help explain this more clearly so this year, I made a point of recording some data in our garden with our light meter to show the dramatic difference in sunlight between the summer solstice (ie. June 21, the longest day of the year) and the winter solstice (ie. December 21, the shortest day of the year).

To put it simply, the lines on these graphs rise when there is more sunlight available and fall when there is less sunlight. The yellow area under the curved lines represents the total amount of sunlight that a plant would receive between 8:00am and 6:00pm in one typical day. On a perfectly clear day with not a cloud in sight, these lines would be nice smooth curves. The bumpiness is due to variations in cloud cover throughout the day. Based on these graphs, there is at least 10 times more light available during the summer solstice as there is during the winter solstice. I expected there to be a noticeable difference in intensity and I also knew the day length would be a lot shorter in winter, but I am still surprised to see how dramatic the change in light intensity is between the seasons. I will plan to write more about the light changes through the seasons once I have gathered more data from the Spring and Fall Equinoxes as well.

Lesson #6 - Early Carrots in the High Tunnel

Back in 2018, we built a high tunnel and have certainly been enjoying the space since then but it is taking time to fully understand its growing potential. The tunnel really does have a climate of its own thanks to its clear cover.

Our major motivation for building the tunnel was to optimize production of valuable warm season crops like cucumbers, tomatoes, and peppers. While the tunnel works wonderfully for this purpose, I am still working on the question of how best to use the tunnel space before these heat loving crops need to be transplanted there. We are typically only transplanting our tomatoes and cucumber in mid May and it would be a shame to leave the space empty until then. At the same time it's hard to find good candidates to fill that tunnel space early in spring because these crops need to mature quickly enough so that they can be taken out of the beds in time for the trellised tomatoes and cucumbers to takeover. Obvious choices are quick growing greens like spinach and lettuce but we only need so many greens, so my mind wandered to other slower crops that could benefit from some early heat.

This spring, I set out to grow carrots in the tunnel as a relay crop with our tomatoes. Here’s how it worked. The carrots were seeded in the outer rows of this 30 inch wide high tunnel bed on March 26 and tomatoes were transplanted down the centre gap on May 16. (Seethe dated photos below.) The carrots made use of the bed space long before the tomatoes could have been planted, and this head start helped them mature before the tomatoes fully occupied the bed. Since the tomatoes are much taller plants than the carrots, they could outcompete the carrots despite being planted in the bed much later. The tomatoes actually appeared to experience no negative effects from their numerous carrot neighbours.

Left image shows carrot seeding on March 27th.

Centre image shows interplanting on May 22nd.

Right image shows carrot harvest on July 6.

The interplanting seemed to reach its peak production capability in early July. With the trellised tomatoes now casting a lot of shade, the carrots couldn’t continue to grow properly and their leaves were starting to stretch, searching for more light. If we had planted the carrots and tomatoes together at the same time, the carrot crop would be a write off, but since we gave the carrots a head start they were now mature enough to pull out of the ground. We harvested 60 lbs of carrots in total from the outer rows of two 50 square foot high tunnel beds. While that’s not quite as much as we could expect from full beds of carrots in mid summer, it’s a lot more than what we would have got had we just left this space empty before planting the tomatoes. I think we'll be doing this one again, and considering the exceptionally late spring we had this season, I suspect we could achieve even earlier harvests from our carrots.

Lesson #5 - Ants Versus Borax

One of the new garden plots we acquired a couple of years ago came with a very well established ant colony positioned right in the middle. I wasn't excited about their presence but my first approach was to just see if we could peacefully coexist. Uhhh...nope. In year 1 they ate my carrots, in year 2 they ate my lettuce, and this year they ate my tomatoes, so I prepared for battle.

The challenge with ants is to somehow disrupt their habitat without ruining your garden at the same time. Since they live underground, it's next to impossible to avoid disturbing your plants with any type of physical intervention during the growing season.

What turned out to be an effective solution was mixing a bit of borax from our laundry shelf with a sugar paste. The borax is deadly for the ants but they eat it anyway because they can't resist the sugar. Apparently, the goal with this technique is to balance the proportions of borax and sugar just right so that the ants who pick up the tasty treat don't die before they bring it underground to share with their buddies. We eventually accomplished this, but it took some experimenting with the proportions of borax, water, and sugar in the paste.

We made the sweetened borax available to the ants by setting it in covered containers on top of the soil. Several holes were cut in the sides of the containers to allow ant access. The lids were left on the containers to stop rain from diluting the solution and/or washing it into the soil. You don't want to simply pour this solution onto the soil because there is a good chance that will harm your plants. I am speaking from experience here, having damaged a few of our tomato plants this way. I apologize for the lack of photos here. It appears as though I don't take as many pictures when I'm angry.

Lesson #4 - An Experiment in Onion Spacing

In this trial, we set out to measure how the overall yield would be impacted if onions were transplanted in clusters instead of just single plants. Why is this a big deal? Well, If you are needing to raise and transplant hundreds or even thousands of onions for your homestead or small farm, you could potentially save a lot of transplanting time and nursery space if you raise your onion seedlings in multiplant blocks and even transplant these onions in small bunches out in the field. We have grown onions like this other years, so we know it works. I have just never made an effort before to run a side by side trial in order to compare single plant soil blocks with multiplant soil blocks. So this season, I set out to run two trials with two different onion varieties comparing multiplant blocks with single plant blocks.

Onion seedlings
Here's a look at the single and multiplant soil blocks for our onion trial.

The photo above shows a comparison of the 1 inch single plant soil blocks with the 1.5 inch multiplant soil blocks that we used for this trial. The larger mulitplant block contains 3 separate onion plants and about the same volume of potting soil as the 3 smaller blocks combined. We needed to keep the overall plant density in our beds the same for a fair comparison so when it came time to transplant these onions in the field, the multiplant blocks were spaced much further apart than the single plant blocks.

Once the numbers were all tallied up from this trial, we found that the single plant onion blocks produced onion bulbs that were 10% larger on average than the onions planting in clusters. You can find the full results from this trial published here. The write up includes our planting procedure, all the data, and a lot more photos. If you want to work on your onion game, check it out.

Lesson #3 - Making the Most of Our Parsnip Beds

I love including parsnips in our vegetable garden but I hate waiting for them to germinate. Even in ideal conditions they won’t be popping up above the soil much earlier than 21 days after seeding. Parsnips also need quite generous spacing to perform at their best. When we space plants 3 inches apart in their rows, we can fill one of our 30 inch wide beds with just two outer rows of parsnips along our two lines of drip tape. These two parsnip growing characteristics make it a good candidate for interplanting. We want to make use of that valuable open space while the parsnips are taking their sweet time.

So, what can we do with that extra space in the middle of the bed while we’re waiting for the parsnips to pop? Well, since the timing of this parsnip planting is early spring and the crop would have to fill the space and get out quickly before the parsnips need full sunlight access, we can narrow down our choices pretty quickly. Our top picks would be baby spinach and radishes. These are two crops quite fond of spring weather and they can both be in and out quickly in about 30 days. Other options could include quick greens like lettuce, baby kale, and arugula, but since those crops can often be cut multiple times especially in spring, they would be better used in a bed that they could occupy for 45 days.

The photo above shows our parsnip and spinach interplanting from earlier this spring. Both crops were seeded on May 7th and this photo was taken when the spinach was harvested on June 8th. The cut spinach plants can be simply pulled out of the centre to allow the side rows of parsnips to takeover the bed for the rest of the season as shown. In this particular bed we harvested 5 kg (11 lbs) of baby spinach all while we were waiting for the parsnips. That adds a lot of value to our parsnip bed.

Lesson #2 - Have Your Celery and Eat It Too

An essential strategy for getting the most production from your vegetable garden is minimizing the amount of time that any of your growing beds are empty. With this strategy in mind, we have started to approach the harvesting of our celery differently.

In the past, we used to chop off our celery heads entirely at their base when they were ready to harvest. It's quick an easy to remove a full celery plant at the base, but each time we do this, we leave a gap of empty space in the the celery bed. That amount of empty space continues to grow as we selectively harvest more of the celery heads. A possible way to fill this empty space would be to transplant other crops in place of the harvested celery but this would be overly complicated because of the gradual harvest of the celery bed.

Celery plants in garden.
This bed of celery has already been harvested numerous times by late August.

With a small modification to our celery harvesting method, we can keep our celery bed full and productive for the entire growing season. Instead of cutting and removing the whole head at the base like most larger growers, we snap off the outer stems as needed and allow the inner stems to continue growing. It takes a little more labour to harvest single stems instead of the whole plant, but this simple difference in harvesting techniques can allow us to start harvesting earlier and still increase our overall harvest from this bed. This season we progressively harvested 46 kg (101 lbs) of celery stalks from one 50 square foot bed and added a final harvest of 20 kg to that at total at the end of the season when we cut each plant at the base.

The lesson here is not to model your harvesting techniques after what you see in the grocery store. We typically only see full celery heads in the grocery store, and it’s easy to understand why celery in that form makes more sense for harvesting and shipping on an industrial scale. It just doesn’t make sense for us as small scale growers. Had we harvested full heads from this space, we would have had to start again with another crop from seed or transplants, and we would lose all the growing momentum that we had with these well established celery plants. We would much rather keep our space green and productive as long as our season allows.

Lesson #1 - Grafted Tomatoes Prove Their Worth

First, a little background information for those of you new to the concept of grafting. The basic idea of grafting is to attach the top of a tomato variety you would like to eat to the bottom rootstock of a tomato variety that has strong disease resistance and more vigorous growth. After the grafting process, you end up with a tomato plant that looks like the ones in the photo above. At the time of the photo below, the stems were held together with little clips, but those fall off once the graft heals and the stems expand.

grafted tomato plants
Newly grafted tomato plants are first held together with silicon clips.

For our experiment, we grew one 50 square foot bed of regular Moskvich tomatoes (an heirloom semi-determinate tomato) and one bed of Moskvich tomatoes grafted to Fortamino tomato rootstock. It wasn’t obvious early on, but a few weeks into the season, the grafted plants began to show obvious signs of increased vigour. Looks can be deceiving though, so I suppressed any presumptive excitement and awaited the numbers.

When I was able to finally tally up the totals, the difference was remarkable. The yield of the grafted tomatoes was 170% of the yield of the non-grafted tomatoes. All other conditions were kept consistent as much as possible. The beds had the same irrigation schedule, the same spacing, the same trellising and pruning, and the virtually identical growing conditions being only a couple beds apart on the same plot.

The differences didn’t end with yield. I also compared the root systems of the grafted and non-grafted plants. If you'd like to see all the details about this trial, you can find the full report here, and based on these results, you can bet that I will plan to do more tomato grafting in the future.


That's a wrap for this year's biggest lessons from the garden. I hope you found some of those points useful and relevant for your context, but most of all, I hope this post inspires you to keep learning about the growing subjects at the top of your list. You can't expect to figure out everything in one season because all of the possible problems and questions don't present themselves at the same time. Thank goodness for that! My challenge for you is to simply commit to learning a bit more every year. Your growing ability and confidence are guaranteed to improve along the way and you'll be a master gardener before you know it.

In case you missed the first two parts of this series, here they are: Part 1, Part 2.


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