How Plant Spacing Affects Yield and Fruit Size in Vegetable Gardens
- Jared Regier
- Jul 31
- 11 min read
Ever wonder how much space your vegetables really need? Most seed packets offer basic spacing advice, but I can't remember the last time I actually followed the recommended spacing on a seed package, especially when it comes to maximizing my garden's output. Instead, the plant spacings that I use today and recommend to my Seed to Table students are the spacings based on legitimate scientific trials. In fact, one of my favourite folders in my collection of vegetable resources is the one with all of the studies on plant spacing. Nerd alert! I know. I must confess that I seek out studies and graphs about vegetable trials because the true science is where you can find the real gold, as long as you have the patience to sift through a lot of pretty dry writing and complicated data. If this doesn't sound like a good time to you, don't worry. I'm going to save you some time today and share some general patterns of plant spacing that I've picked up over the years. We'll look at how spacing affects the total yield, the size of your fruits and vegetables, and how plants adapt to the space they're given. I hope to leave you with an understanding of the basic effects that plant spacing changes will have on your crops and enough confidence to tweak your plant spacing to match the desired production you are looking for.
Why Plant Spacing Matters
Your garden is a competition. Everything you have planted, weeds included, is fighting for a limited supply of sunlight, nutrients, water, and plant spacing is a huge factor in determining how much of these resources each plant access. Therefore, plant spacing plays a crucial role in the overall health and productivity of your growing space, influencing everything from disease pressure to harvest efficiency. When plants are spaced too closely, airflow between them is restricted, creating humid microclimates that favour fungal and bacterial diseases. Leaves stay wet longer after rain or irrigation, increasing the risk of infections like powdery mildew or blight. Tight spacing also limits root development, as neighbouring plants compete for nutrients, water, and soil volume, often resulting in shallow or underdeveloped root systems. Sunlight access is another key factor affected by spacing — overcrowded plants tend to shade each other, especially in dense or vining crops, which reduces photosynthesis and encourages weak, leggy growth. Finally, the practical work of harvesting becomes more difficult when plants are too close together. It's difficult to get the most from your garden when you can't see or reach produce without damaging foliage or stepping on nearby crops. Giving your plants enough room can significantly improve their ability to stay healthy, grow strong, and produce a bountiful, accessible harvest.
The Relationship Between Spacing and Yield
If you're growing food in your garden, then you're likely interested in growing as much food as you can. It's obvious that planting too few plants will leave us with less food, so our intuition may tell us that if we plant our crops at a higher density, we'll end up with more food, but that's not always the case. Remember that higher plant densities also mean more competition for the resources plants they need to thrive. If we push the density too high, we can often end up with less food than we could have harvested if we has used a much lower plant density.
A classic bell curve describes the relationship between spacing and yield.
Let's use a familiar example of carrots to illustrate the plant spacing bell curve. The most common carrot growing mistake for new gardeners is seeding their carrots too liberally and ending up with overly dense rows or beds that produce lots of carrot tops and very tiny carrot roots. In these scenarios, a lot of carrot plants are growing but the total yield is dismal because the plants just don't have enough space to fully develop.
If you've already planted your carrots too densely, you can salvage the season by thinning out the extra plants, but this task is so slow and feels like the biggest waste of time. I think everyone needs to do this at least once so that they are motivated to plant their carrots at the right density next time!
At the other end of the bell curve we have carrots that are too widely spaced. The photo below shows carrots planted on an industrial scale, and we see huge gaps between carrot plants, but this is only to allow room for heavy machinery. It does nothing to increase the total yield per square foot.
Some of this extra wide spacing has trickled down into the smaller gardens of home growers where the extra space is totally unnecessary. In this smaller context, there is no need to allow clearance room for large machinery so the large gaps between each row of carrots are only wasting valuable space and promoting weed growth.
In both of these cases with extra wide carrot spacing, the roots may mature to a larger size because there is so much space between plants, but the extra generous spacing puts us on the upper end of the bell curve far past the sweet spot. In this range, it doesn't matter if the carrots grow to their largest possible size. The total yield per square foot will still start to drop because of all the unused space.
To optimize our total yield, we need to find the sweet spot for carrots, and that means switching to bed production instead of single rows, and then spacing carrots appropriately throughout that bed area. In one of our standard 50 square foot beds, I aim to have about 800 evenly spaced carrot plants. This lighter spacing feels too sparse in the first couple of weeks, but the plants soon cover the wide bed with a full canopy of leaves. Each plant has enough space to produce a good sized carrot, the full coverage of leaves conserves soil moisture and suppresses weeds, and best of all, my total yield is as high as possible.
Plant Adaptation in the Sweet Spot
So where exactly is the sweet spot for each crop? That is one of the biggest questions I needed to answer when I first started my market garden. If the answer isn't the spacing listed on the back of most seed envelopes, then where is it? Well, I found some answers in scientific studies on plant spacing, I found some answers in the spacing tables of other market gardeners, and when in doubt some answers still needed to come from trials of my own. I now share all of these answers with my Seed to Table students inside our course community.
What I've found interesting along the way is the remarkable ability of plants to adapt to their given space inside the sweet spot. At the centre of a bell curve (shown earlier) is a relatively flat zone where the yield stays about the same even though the plant spacing is changing. This constant yield occurs because plants are able to adapt their growth to match their allotted space. This is good news for us because it means that we do have some wiggle room when it comes to plant spacing.
One squash spacing study I read this spring illustrates this sweet spot wiggle room really well, so I want to share some of the findings with you as an example. This trial, conducted by Wetzel and Stone of Oregon State University, varied winter squash in-row spacing on irrigated and non-irrigated plots in order to measure the impacts on the quality and quantity of harvest. The in-row spacing used in the irrigated beds was 0.2, 0.3, 0.5 and 0.8m between plants, which corresponds to 7.9, 11.8, 19.7, 31.5 inches. The spacing between rows was 1.5m or 5ft. The squash varieties tested included Bonbon, Burgess Buttercup, Crown, Delica, Sunshine, Sweet Mama, Tetsukabuto, Winter Sweet and a few others.
We'll just concern ourselves with the results form the irrigated trial and these numbers are summarized in the graphs below. First off, we notice from graph A that the overall yield stays relatively consistent across all spacings. We only see a small peak in the middle, indicating that maximum yield would be achieved with a spacing close to 0.3m between plants in the row. Wow, that's tight, even with widely spaced rows!
I was surprised by how consistent the total yield was, even with big changes to the plant density. If yield is staying relatively consistent while the plant density is varied between 10,000 and 30,000 plants per hectare ( graph C ), then there must be another responding variable that is changing significantly? We find the answer in graphs B and D. Graph B shows that the lower density plantings produced significantly more fruit per plant on average, and Graph D shows that those fruit were larger on average. This data confirms the prediction of the spacing bell curve we discussed earlier. That is, a widely spaced squash plant should be able to produce larger fruit and more of them. That's how 10,000 widely spaced plants can produce almost the same total yield as 30,000 tightly spaced plants.
The shift in fruit size is illustrated more clearly further on in the study, when we see a set of histograms for a few of the squash varieties. These histograms show a obvious trend in the distribution of the different fruit sizes. The most widely spaced plants in the trial (outlined in red) show a consistent tendency toward producing larger sized fruit, while the more tightly spaced plants in the trial show a consistent tendency to produce more smaller sized fruit. Note the fruit sizes of each letter category at the bottom of the chart.
With this data in mind, I was ready to plant my squash confidently at a large scale. My deep dive into squash spacing this spring was triggered by a move to some larger 100ft long beds in a U-pick garden zone I am building on our new property. The row spacing here (see photos below) is increased to 6 ft from our usual bed spacing of just 3.5 ft, so I was willing to tighten up our winter squash spacing a little, but when a study like this one shows a maximum yield achieved at 0.3m (1 ft) in-row spacing, I don't just blindly follow this recommendation. There are other factors to consider too. The cost of high density spacing like this is that I have a lot more squash seedlings to raise and transplant into the field, and I don't necessarily want to produce more fruit if it's all smaller. That's a lot more handling. So this is where we need to use the sweet spot wiggle room. Since all of the tested spacings were near the top of the bell curve with pretty similar total yield, I opted to go ahead with a 2 ft in-row spacing for my squash beds this year, even though this is twice as much space as the top performing in-row spacing in this study. According to the data, a spacing like this should give me a respectable yield and good fruit size, but with only half as many squash seedlings to raise and transplant in the spring. I always like the idea of reducing unnecessary labour, especially when I'm working with my "helpers".
Since we're still just half way through our growing season, we'll have to wait a while longer to compare yields to our expected targets for winter squash, but plants are looking healthy and productive so far. They are definitely making use of their wider row spacing.
Squash is a great crop for an example of plant adaptation like this because their vigorously growing vines allow them to expand into all available space. Tomatoes, cucumbers have similar abilities. However, extreme adaptation like this is not the norm in the vegetable world. A more stationary crop like onions will adapt a little to spacing variations, but an onion can only grow so big even with extra wide spacing. It just doesn't have that same vining ability to explore and conquer. As a result, the sweet spot for plant spacing becomes much narrower for the more stationary crops in your garden... which is pretty much everything else.
How to Choose the Right Spacing for Your Garden
There's no question that plant spacing will influence your total garden yield, the size of your fruits and roots, and overall plant health, so your first objective should be to make sure you are using a plant spacing that falls within the sweet spot for each of your crops. To make sure you've got your numbers right, you can choose to do a bunch of our own research or join the Seed to Table course community so you can starting using my top recommended spacing for each crop.
Once you are sure that your plant spacing is within the sweet spot, then you can confidently start to play with that spacing a little bit to adjust the quality of your crops. Would you like your carrots to be a little larger? Just widen the average spacing a bit. Would you prefer if your cabbage heads were a smaller more manageable size? Just plant them a little closer together. Remember that the top of the bell curve is relatively flat so your total harvest quantity will be about the same as long as you stay within that sweet spot.
Here are two simple examples of plant spacing adjustments I have made.
In my first few farming seasons, I noticed that the root size was really variable and a lot of my labour in growing beets was in the harvesting, washing, and bunching actions. I increased my beet spacing slightly in order to grow larger roots and give each plant sufficient room to thrive. This meant a 1 kg bunch of beets now needed fewer plants and less labour to pack. An added bonus of the wider beet spacing was a more consistent root size when I wanted to harvest a full bed at the same time.
In the case of garlic, I've opted to not grow the largest possible heads. I've done my own controlled trial with this crop and this showed clearly that wider spacing could allow me to produce much larger heads. However, this is one case where bigger isn't necessarily better. When we use garlic in the kitchen, we're already breaking the heads into cloves and just using one or two cloves at a time. What good is it in having a head of garlic that is twice as large? I don't want to save slices of half cloves in my refrigerator because they were just too big. My customers probably wouldn't want to pay the true value of extra large garlic either. With this in mind, I've kept my garlic on the tighter side of the sweet spot so that I have more comfortably sized heads.
I hope this short lesson on the impact of spacing helps give you the confidence to shift your own plant spacing to match what you are looking for from your garden. Once you've learned to meet the basic needs of your plants, it can be fun to fine tune things like this. To learn about the other core variables you'll need to control in order to optimize your garden's performance, head over to my free interactive workshop. You'll be growing your own 200g heads of garlic in no time! That is, if you want to.
