Estimates for part-time microgreens production in a greenhouse

This is a continuation of my series on figuring out profit potentials from different production systems for the small farm enterprise I’m launching this year (2015) in Quebec.

In the last bit, I applied some of the numbers from the SPIN model for use in my market garden. This is just one arm of the business that I want to run though. In addition to the market garden, I’m also planning on having a micro-greens production, which will be done inside a greenhouse, and perhaps partially under lights as well. The details haven’t been worked out yet, but I’d like to paint a broad picture that will guide further planning and development.

If the 30–60 DTM (days to maturity) dictated by the SPIN model is interesting, microgreens become even more compelling. In some cases, we may be looking at 10–15 days to harvest (we can’t call microgreens “mature” I guess). So in the time it takes outside to raise an already rapidly-growing crop (30 days, for instance), we may be able to turn around 3 crops of certain microgreens.

One of the more interesting business models/courses I’ve seen regarding doing a small-scale microgreens production comes from Luke Callahan. His course advertisement materials say you can make $1,000 a week growing & selling microgreens. Which perhaps you can. I’m not concerned with trying to reproduce every detail of his plan here, only to take the general outline and apply it to my own purposes.

In his model, he’s using the typical black plastic greenhouse-style flats, which usually come in 11" x 21" trays. As I’m on a mission to eliminate plastics in my vegetable production, I will build some flats of my own out of wood, which I will round up to have a soil surface area of 12" x 24.” That also gives me a more even number for square footage purposes of 2 square feet per flat.

Now, I’ve seen all kinds of numbers thrown around for how much you can gross per flat of microgreens. But I’m going to stick with one of the more conservative/low figures that I’ve seen which is $15 per flat (or $7.50 per sq. ft), just so I don’t get ahead of myself. Microgreens are virtually unknown in this market, and though I’m certain I can grow a superior product, I’m not totally certain how ready for it people will be here. So we’ll stick with $15 as a figure per flat until we see otherwise.

Now, I’ve calculated elsewhere I can potentially do $400 in my market garden, which will be all direct seeded plants, intensively planted and cropped in sequence, so that each bed is used multiple times per season. I like the idea of being able to make $1,000 a week in microgreens, but for now, I suspect it will be more of a supplement, rather than my main enterprise.

So let’s aim for a microgreens gross income of $200 per week to get started, added to my $400 from the garden. Over 21 weeks of available growing season, that’s around ~$12,600 for the season (before adding in income from animals — which we’ll cover in a subsequent post).

Let’s say, for arguments sake in one month, each 1'x2' microgreen flat can produce three crops (averaging about 10 days per production). So that’s $45 ea per month, per flat. Maybe its more easy to calculate per month, since the production takes a bit longer than one week. $200 a week, four times = $800 a month production/sales target.

$800 / $15 per harvest = 53.333 harvests

Or

$800 / $45 production per flat per month = 17.777 flats

Or

18 flats of 1'x2' * $15 per harvest * 3 times per month = $810

In square footage of either greenhouse or indoor table/rack growing space, 18 flats that are 2 sq ft each will be 36 sq ft.

I tried laying that out in a graphic:

As a floor plan for a custom-built mini-greenhouse which would be 10' long, by 6' wide, by probably 6.5' at its peak: just high enough to walk into. The greyed area is kind of an overlap/wiggle space, since my flats will need to be slightly larger than 1'x2' to have that as their soil surface area. If I push past 10' in length, I can easily add in two more flats to have 20 flats yielding three times per month (more like $900).

Anyway, it would be something like this, but maybe just a flap on both ends, rather than a full-on door, as most of the season it will be hot to have the door closed:

[via]

You can grow microgreens direct in soil (on the ground) but it doesn’t seem advisable based on what I’ve seen. Weed seeds are too prevalent, and rain can be surprisingly destructive with these guys, so a greenhouse or an indoor growing area under lights will be critical.

Including lumber, plastic, hardware (screws and staples), I imagine I could build a little greenhouse like this for around $100 each (perhaps multiple ones if I find its very successful).

One of the nice things about microgreens, is that you don’t do much weeding at all — except for any weed seeds that happen to get blown in by the wind, since we’re purchasing (hopefully sterilized) soil. Buying in soil routinely is of course an expense, but it’s a small one (I calculated a while back that between seed and soil, each tray would cost somewhere under $1.50 each time it’s planted. Scraps & leftovers would cycled back through compost, or thrown to the chickens to sift through. We may not have to do much weeding with microgreens (really the main job for the rest of the garden), but we will have to do a lot of processing: planting, harvesting, cleaning, packing. So it’s not nothing as far as work goes, but its definitely something interesting as far as adding another diversified revenue stream for a small farm.