It’s important to understand that urban farmers cannot and should not try to grow everything. Because urban farmers operate on much smaller land bases than most other farmers, growing some crops is simply not economical for us. So, which crops should urban farmers focus on?
There are some other factors such as distance to market, market value, yield per square foot and crop perishability that also come into play. A 19th-century German economist named Johann Heinrich von Thunen proposed the idea of dividing cities into rings of agricultural production in his book The Isolated State in 1826.
The basis of his thesis was that certain crops should be grown in certain points of a geographical area based on transport cost, land value and distance to market. To highlight this idea in a very obvious way would be to say that it doesn’t make economical sense to grow grain in the center of a city.
Grain has a long shelf life so it doesn’t lose nutritional value through transportation, and it also has a low yield ratio based on the value of land per square foot, making it nearly impossible to make a profit on small land bases. On the other hand, to grow and ship highly perishable salad greens from a 1,000 miles away is not economical either. Consider all the factors that make fresh greens valuable: they have a short shelf life, a high yield per square foot ratio and a short date to maturity.
This makes the idea of growing this crop close to where it’s consumed a good choice. Short date to maturity is very important for the urban farmer: these crops can be replanted many times over to assure the maximum amount of production based on the yield per-square-foot ratio.
The Cuban Special Period is another great example of this fundamental practice. As the Soviet Union was collapsing in the 1990s, Cuba lost access to most of its fossil fuels and conventional fertilizers used for agriculture due to an embargo from the US government. During this time, Cubans were starving, and drastic measures had to be put in place to feed people fast.
Crops like salad greens were planted in the inner city because they could feed people quickly and were harvestable close to where people lived. Such innovations are why Cuba is still seen as a world leader in urban agriculture. In many cases, necessity is the mother of invention.
Von Thunen’s and Cuba’s approaches are fundamental when deciding what crops are most suited to urban agriculture production. Similar principles also apply when we are looking at crops to grow on an urban farm, but they are a little different when taking into account what makes the most sense to grow from logistical and financial sides.
In my own experience, there are five characteristics that make a crop well suited for growing on a small land base in a city. I summarize these characteristics as a Crop Value Rating (CVR). CVR works by assigning each crop you want to grow one point (out of five) for each characteristic it has:
- Shorter days to maturity (60 days or less)
- High yield per linear foot (½ pound per linear foot, per 30 inch by 25-foot bed)
- Higher price per pound (minimum $4 per pound)
- Long harvest period (4 month minimum)
- Popularity (high demand, low market saturation
Let’s look at each category and what it means.
1. Shorter Days to Maturity
Shorter days to maturity (DTM) mean that the crop grows and is ready to harvest within 60 days or less. Radishes are 28 days, so they’d score here. Spinach is 45, so it scores.
Tomatoes are often 70 days or more, so they don’t score here. However, I don’t grow anything on my farm that has more than 70 days to maturity from the time it is set into the ground.
This means that I will grow only a tomato variety that is ready in about ten weeks from transplanting; the same goes for carrots, beets or anything else that would have a longer DTM. I always try to grow the fastest varieties, no matter what the crop is.
2. High Yield per Linear Foot
Consider how much yield will come from one linear foot of bed. For example, a cabbage takes around 80 days to mature. When the plant is at 75% maturity, it takes up around two square feet in a bed; all of that space will yield only one item that is sold once, at a relatively low price.
Compare cabbage to yield from radishes. Radishes are ready in 28 days, and in the same space as one cabbage, I could harvest eight bunches. The general idea is to that you get maximum value from space.
3. Higher Price per Pound
Generally speaking, I don’t grow anything that sells for less than $4 per pound. My lowest value crop to meet this requirement would be cherry tomatoes at $4 per pound.
Some of my tomatoes score lower, but that doesn’t mean I won’t grow them; it just means if I had to cut a crop from my list, they might be the first to go. Kale or radishes at $5 per pound also meet other criteria: long seasonality and high yield per square foot. The highest price per pound would be microgreens at $20 per pound.
So, in order to meet this price criteria alone, a product must be sold for at least $4 per pound. This does not mean don’t grow anything that sells for less than $4; it just means that, if you do, make sure that crop meets some of the other criteria as well.
4. Long Harvest Period
This can mean either of two things:
- It’s a crop I can keep planting and replanting for a minimum four-month period.
- I can keep harvesting the same crop for four months.
Radishes, for example, I can keep planting all season, so they have a long season in that regard. A crop like kale I can harvest for most months of the year, except during the heat of summer. Tomatoes don’t have a long harvest period, but I’m going to grow only varieties that have the longest period I can find, such as indeterminate types that will bear fruit for many months.
High demand and low market saturation are perhaps the single most important of characteristics of them all. You can grow high-value and quick-growing crops until you’re blue in the face, but if nobody knows what they are or wants to buy them, they’re not worth anything. I learned this the hard way: one year I drastically scaled up my microgreens production.
I quadrupled my output from one year to the next, and saturated the market. I was no longer able to sell them all. They also became an item that other farmers started to grow because of their high value. Once the market becomes saturated, pretty quickly they became passé to the chefs. That left me sitting on a lot of product that I couldn’t move.
Kale is a perfect example of a crop that might not be the highest value per pound— but it’s very popular and I never have to work too hard to sell it. It might not have all of the criteria for our CVR, but it scores overall because of its popularity.
Some Examples to Illustrate CVR
Let’s look at three crops that all have a CVR of from three to five. (Keep in mind that this rating maybe different for the same crops in differing areas, based on what demand there is for it; is the market is saturated or is there high demand?)
In my area, a crop like spinach rates 5/5 on the CVR. Spinach has short days to maturity (45 or less), a high yield per linear foot (1.4 pounds per foot), a higher price per pound ($7 per pound); it has a long overall harvest period (10 months), and it’s a common vegetable that is popular because of its many uses. Cherry tomatoes on the other hand score three out of five.
They have a high yield per linear foot at 7 pounds; they can command a good price at $4 per pound; and they are very popular with both of my market streams. Beets score four on the scale. They meet all the requirements except a short DTM: they take 60–70 days to mature.
Using CVR rating, you can establish a system in which crop choices are rated based on logistics and economics. Most crops on my farm score a four out of five on average, with a few threes and fives. The principle idea is that, the smaller the land base, the higher you want the majority of your crops to score on the CVR scale, to make up for the loss of land.
The larger the land base, the more crops you can include that score lower. If you were to grow solely on ¼ acre of land, you should grow only crops that score fours and fives. On any smaller farm, grow only fives. On ½ acre or more, include more variety in order to capture more market share: grow threes, fours and fives, and perhaps even some twos.
Cash is King— Quick Turnover
Following these basic principles, we can easily see why some crops are just better suited for urban production.
The other factor that is critical here is cash flow. Fast-growing annual vegetables have a fast payoff. They are planted and, in some cases, ready for harvest in 30 days. Planting perennial crops often takes years to see a return. Quick turnover is particularly important when the farmer doesn’t own the land.
Waiting for a three-year return on investment for an asparagus crop, when you might have access to that land for only three years, is not a sound business decision. In all these cases, we must come back to basic economics and sound business practices.
Many people want to grow vegetables that they like or perhaps because they have some ideology, such as health or environmental benefit, based around them. It’s good to have ideology and an ethical stance on things, but if your ideology makes you go broke, then nobody wins.
Don’t abandon your ideology; just keep it in your back pocket and be practical. As you make small successes, bring some ideology back and implement it incrementally. If you start with too many grandiose ideas, it will be hard to get started.
Don’t think that you’re selling out because you can’t use all the ultimate ideas of sustainability at once. It’s good to have huge ideas, but make small steps to get there. This system is about going from A to B. What the ultimate form of sustainable agriculture looks like,
I’m not totally sure, but we’re taking steps to get there, and we figure it out along the way. The important thing is: first, you need to make living at this. Otherwise, you’re working somewhere else and are doing this on the weekend.
You must have cash flow, and this is why I grow the crops that I do.
Quick and Steady Crops
All the crops on my urban farm are divided into two categories, and again, these crops are all based on what makes the most logical and economic sense to grow in a city.
Quick Crops grow fast and are often, but not always, harvested at once to free up space to be planted again.
Steady Crops are a little slower but are harvested over a long period (most often harvested on a weekly basis throughout the season). In no cases do I grow any long-season crops such as onions, potatoes, cabbage, winter squash, melons, corn or garlic.
Crops such as broccoli, cauliflower, brussels sprouts, beans and peas are not great for my farm either. And even though some of these crops may have shorter dates to maturity, they have a very low yield per linear square foot. I don’t recommend that any urban farmers grow crops like this for commercial production; however, to grow them for your own use is another story.
Quick Crops are ready for harvest in 60 days or less. For the most part, I replant all crops in this category on an almost weekly basis. When I plan my farm, I don’t plan where all my Quick Crops will go. I simply decide what areas will be in Hi-Rotation and that’s it.
I leave the exact details of these crops to bend to the demands of the market, and the exact amount that gets planted on a weekly basis will change from season to season. This is partly how I maximize the economic output of my farm. If something isn’t selling, it gets terminated and something else gets planted in its place immediately.
Steady Crops are those with a date to maturity of 60 days or more, and they are called Steady because they are often steadily harvested.
Tomatoes, kale and summer squash, for example, are picked weekly during the high season and constantly regenerate, whereas sometimes carrots can be totally cropped out at once or harvested a few rows at a time over a week or so. In some cases, beets can be thinned out over the course of a few weeks.
All Season Production
Part of what makes my farm profitable is having a steady level of production for the entire season. My season here in Kelowna, BC, is 30 weeks long on average, and the key here is to maintain a strong income for the entire period.
This is not like the typical farming season, where the shoulder seasons are low and the summer is high. This is why you’ll notice that a lot of the crops I grow are spring crops. The majority of vegetables I grow and the base of my farm income come from crops that I can grow in almost all seasons.
This is very important because it allows for a strong foundation of cash flow all year. Granted, there is a small amount of a seasonal spike in the summer which is inevitable for any farm. But the main idea is to have strong weekly sales all season, and I choose the kinds of crops I do based on this idea.
With some really simple season-extension techniques, it is possible to have some field production all winter, even in some Canadian winters. There are three types of greens I can have almost all winter in unheated greenhouses or low poly tunnels: lettuce, spinach and kale.
It’s also possible to have carrots in the ground all winter. I use a technique called overwintering to achieve all of this. Growing microgreens indoors is also a great way to have production over the winter. You need to spend a little on infrastructure, but it’s possible to make $2,000 per week in a 400-square-foot area growing microgreens.
It is important to have a strong summer production for two main reasons:
- You need to satisfy demand as it occurs.
- Spring crop production will slow down in summer heat.
Yields for some crops will drop in very hot climates, and this happens in my area. We are in a high desert here and experience daytime temperatures of 104°F some days.
Crops like arugula, lettuce and mustard will yield up to 50% less than in the spring, but they will grow faster, so it can be a bit of a trade-off. Also, I cannot grow crops like spinach and bok choy at all during summer. They will bolt too fast and sometimes not even germinate at all.
For the summer, I make sure that I have strong production of indeterminate tomatoes, summer squash, some peppers and a lot of carrots ready to go as the spring crops start to taper off.
The nice thing about the summer crops that I grow is that in their early stages it’s possible to interplant them with some spring crops. This way you can maximize the use of the land while those summer crops are not yet producing.
There are some cases where I will grow a certain crop for a specific chef customer. This is something that is planned long before, and is usually for some type of one-off event.
It’s not something I would suggest doing a lot of, and on my farm, I do this only for chefs that I’ve worked with for a year or two so that we have a good rapport.
These types of crops are most commonly a special microgreen, some kind of baby vegetable like a super small dime-sized radish or turnip, a tiny bok choy or some kind of baby green or herb.
Originally posted 2020-08-10 09:50:49.