What's the ROI on THAT!? Sweet potatoes

What's the ROI on THAT!? Sweet potatoes diversifying my "investment portfolio" aka my garden Mon, 14 Oct 2024 21:55:01 GMT https://carmeninthegarden.substack.com/p/whats-the-roi-on-that-sweet-potatoes I’ve dusted off my spreadsheet for a different kind of analysis—one that hits closer to home, literally . In this series, I’m breaking down the investment of growing crops in my garden to answer a simple question: What’s the ROI on THAT!? Today, I’m diving deep into my sweet potato harvest, examining the costs, returns, and future opportunities for improvement. We'll cover everything from the initial investment to the final yield and even consider what could be done differently next season. If you missed it, you can catch the sweet potato harvest in action on Instagram and TikTok .

Stay with me as we walk through the numbers, because there’s more to gardening than just digging in the dirt—there’s real value here, and I’m excited to share what I’ve learned. As I wait for these sweet potatoes to cure for about a week to allow the sugars to develop fully, I’m scheming all the recipes I’m going to make.

What's the ROI on THAT!? is an ongoing series where I break down the performance of various crops to see if they’re worth the time and effort. Be sure to check out my previous posts on artichokes and garlic , and if you're thinking ahead to next season, I recently shared a detailed guide on growing root vegetables —including sweet potatoes—so you can try them yourself next year.

Carmen in the Garden is a reader-supported publication. To receive new posts and support my work, consider becoming a free or paid subscriber.

COSTS Sweet Potato Slips: $35, I opted for a beautiful tricolor variety from Southern Exposure Seed Exchange. It includes orange, white, and purple sweet potatoes, bringing a fun visual to the harvest.

Soil Amendments: $0, I didn’t need any soil amendments this year—thanks to healthy garden practices and some solid composting over the past few seasons.

Pest Control: $0, No pests, no problems! I don't use any pesticides, and this crop thrived without any intervention. Sweet potatoes for the win.

Labor: $0, Total time investment was about two hours—this covers everything from planting to harvest. Since gardening is my “me time,” it’s free therapy and joy, so no labor costs here.

Total Cost: $35

RETURNS Total Yield: 34 pounds 14.1 ounces. That’s nearly 35 pounds of delicious orange, white, and purple sweet potatoes—enough to keep me happily roasting, mashing, and baking all season.

Market Price per Unit: Sweet potatoes are typically sold in 3-pound increments at around $6.99 to $8.07 based on prices at Whole Foods, Sprouts, and Good Eggs. For simplicity, I’ll use an average price of $7.68 for 3 pounds, which breaks down to about $2.56 per pound.

Total Potential Revenue/Savings: $2.56 per pound × 34.88 pounds = $89.29

(That’s the equivalent cost if I were to buy these at the store.)

Investment Gain (Revenue - Cost): $89.29 - $35 = $54.29

ROI (Return on Investment): Gain / Investment = $54.29 / $35 = 155% Not bad, right?

Annualized ROI: I planted on June 8th and harvested on October 13th, totaling 127 days, or about 0.35 years. So, the annualized ROI is a whopping 1,375.52% —a true powerhouse crop in terms of return!

POST MORTEM & CONSIDERATIONS In the world of investing, reflecting on both successes and setbacks is crucial for making smarter decisions in the future. In investing, we call this reflective process a "post-mortem." The name may not be the cutest, but it fits—because understanding what worked (or didn’t) is key.

We started this series with garlic, and I mentioned early on that these percentages and returns would start to make more sense as we build out our “investment portfolio” (aka vegetable garden). Now that we have more data, let’s compare the ROI across crops and see how they stack up so far:

Beyond the financials, what other benefits do I get from growing sweet potatoes? If we look at calories, this crop packs a punch, which is why sweet potatoes are a staple for so many cultures. In terms of calories per growing time, sweet potatoes are unrivaled. But, when we talk about longevity, my artichokes still hold the crown. Those plants keep producing season after season, offering an impressive long-term gain that rivals what I’d expect from a fruit tree. As we build out this garden investment portfolio, we’ll see how different crops stack up against each other, not just in dollars, but also in calories and sustainability. Stay tuned for more comparisons!

I have a few takeaways from growing sweet potatoes that I’d like to drill down on in more detail:

Cost Efficiency: Although the cost for this crop was low at $35, there could be opportunities to reduce this further. For example, saving sweet potato slips from my own plants or trading with other gardeners could eliminate the need to purchase slips next season. This would improve the ROI even more, pushing my returns higher while maintaining quality. I believe that $35 for 18 slips is pretty steep considering you can get about a dozen slips off of one sweet potato alone. Typically, larger and healthier sweet potatoes will yield more slips. If you plan to grow your own slips, you can cut them off the sweet potato once they reach 6-8 inches in height, and then root them in water or directly plant them in soil.

Exploring Other Metrics: In addition to financial ROI, it might be useful to look at other metrics like calories per square foot or total nutritional yield. Sweet potatoes are nutrient-dense and provide a good caloric return, so calculating the nutritional value could offer another perspective on how valuable this crop is to our household. Additionally, a flavor scoring rubric might be suitable for high impact, low space crops like herbs. I’m really excited about the prospect of including this metric for future analysis.

Return per Square Foot: Something I’ve neglected to analyze is the return per square foot. It’s as simple as measuring the area I’ve used for each crop and dividing the total harvest or savings by that space. For example, for sweet potatoes it would be $89.29/ 40 square feet = $2.23/ square foot. Compared to artichokes, which I also have companion planted with asparagus, fennel, and nasturtium, the return per square foot would be much greater. This helps me see which crops are making the most of my garden real estate. Plus, comparing crops this way lets me prioritize those that give the best bang for my buck. For sprawling plants like sweet potatoes, I also might considering using vertical growing methods in the future to maximize efficiency.

Water: Calculating the cost of irrigation remains challenging due to variability in water usage and cost. It would require me to separately meter my front garden from the rest of my home’s water usage. This is definitely a cost at play, but I don’t really know how much of a cost… if you have ideas to measure this, let me know.

Upfront Gardening Costs: I haven’t figured out a way to factor in the upfront costs of the garden into these calculations in a way that would make sense. For example, how much it cost to build the raised bed, set up drip irrigation, and fill it with soil. This would be similar to factoring in the cost of renting a garden plot. Again, if you have thoughts, let me know.

That’s a wrap for today—I could probably keep going on this topic, but I’ll stop here! For now, I’m off to amend this raised bed with some compost, plant next year’s garlic.

Thanks for reading Carmen in the Garden! This post is public so feel free to share it.

Share