Answer: What's the story with the greenhouses?

 Greenhouses... 

... come in two types--decorative (the ones with beautiful orchids and flowers for visitors to see) and functional ones (see the images above, for growing food and flowers).  

In some places, (e.g., Weifang, China) greenhouses spread over more than 820 square kilometers. 

Seeing all of these from the air sparked this week's Challenge with a few curious questions for you to ponder.  Can you find the answers?  If so, what did you do to discover the results?  

1. How long have greenhouses been around?  If greenhouses date to around Roman times (as I've heard), what were the greenhouses made of?  

I started with a simple: 

[ history of greenhouses] 

as a way to find reasonable resources and read from them directly.  The Wikipedia article on Greenhouses tells of an early origin (30 AD) when the Roman emperor Tiberius needed a "cucumber a day" to keep him in the best of health.  Clever people then made simple frames, "cucumber houses" glazed with either oiled cloth known as specularia or with sheets of selenite.  That's according to the historical description by Pliny the Elder. 

Oiled cloth I understand, but selenite?  It's a crystal that sometimes forms sheets (like mica), but I didn't think it would be very large.  But, a quick search for [selenite] and a couple of images of mineral sample showed me that they can form reasonable sizes rectangles that would be good  for making greenhouse window panes.  (You can even buy nice rectangles of selenite on Amazon.  Who knew?)  

Of course I read several articles to see if they all agreed--and they do--with the most authoritative voice coming from a paper in Horticultural Science (History of Controlled Environment Horticulture: Ancient Origins, by Jules Janick and Harry Paris) 

So... greenhouses have been around for at least 2000 years, with early Roman greenhouses covered in oiled-cloth or small windows of selenite.  

2. What is growing under all of those greenhouses? What's grown in Weifang that needs SO many greenhouses? 

Searched for:  

     [ vegetables grown in greenhouses in Weifang ] 

led me to lots of sources, including an interesting video on X where poster Teacher James walks through some of those greenhouses, pointing out what's growing there.  Answer: LOTS of veggies--I spotted sweet potatoes, pumpkins, tomatoes, eggplants, many kinds of greens, and flowers.  There was no one thing in particular--just lots of varieties.  

Answer: Everything, mostly veggies, of a huge variety and number.   

I also found a really beautiful illustration of side-by-side / before-and-after NASA Earth images at A Greenhouse Boom in China.

Try this yourself at the NASA website.

If you visit the page, you can pull the slider left and right to see how individual places have changed.  On the left, green area are/were regular fields open to the sky.  On the right, gray areas are greenhouses.  That's a huge change in 37 years!  

3. Those robotic greenhouses... how well are they doing?  Has there been a boom in robotic and/or vertical greenhouses in the past 10 years?  Is it a growth industry?  

It's pretty clear that robots are (and will) change the way agriculture works.  The bots aren't perfect, but getting better all the time.  

Let's split this Challenge into two parts: (a) How well are robots in greenhouses doing?  and (b) How well are vertical greenhouses doing?  

Robots: I put this question to Gemini 

[how well are robots working out in greenhouses? Show analyses of how effective robots are at working in greenhouses.  Show both upsides and downsides of robots in greenhouses.] 

This gave me a fairly generic answers, and (annoyingly) without citations.  I had to do an additional query to get the citations, only to find they were mostly old-ish. In a field that's moving as rapidly as this, references from 2020 are not super-relevant.  I had to ask for ONLY works from 2024-2025.  

By the 3rd query, I finally got a reasonable answer in the form of a tradeoff table (pluses and minuses). It still didn't give references, so I had to ask a 4th query. 

When I tried the same task with Perplexity, I got somewhat better results (with citations and links included), although many of the sources were very upbeat promotional sites for robo-agricutural companies.  That's useful data, but they don't show the downsides.  

But it DID lead me to a recent paper (late 2024) that's a survey of robots in greenhouses: "Robots in greenhouses: A scoping review" with an extensive set of citations covering all of the issues and tech needed to build successful working greenhouse robots.  

The paper concludes by pointing out the key problems in building greenhouse robots: they're slow, they're expensive, and they need constant maintenance.  

I also asked Gemini, ChatGPT, Claude, and Perplexity for their opinions (using the above prompts), and mostly got wide-ranging agreement.  The tech is cool and is attracting investment, but 

Bottom line:  There's a lot of promise in putting robots into greenhouses--but there are also a lot of difficult technical and economic problems to solve first.  

Some greenhouse-robot companies (like Iron Ox) go under after a few years of promising work.  The heavy capital expenditures, combined with the economics of operating in such a competitive and cost-sensitive domain, seems to make sustained growth untenable — a common challenge in high-tech farming circles.

Vertical farming test installation. P/C USDA

Vertical Greenhouses: I put this question to our favorite LLMs: 

 [how well are vertical greenhouses working out ? Show analyses of how well vertical greenhouses are performing economically.  Show both upsides and downsides of vertical greenhouses. Give citations.  Include work done in 2024-2025. ] 

Notice that I've learned from the previous queries: This time I added in a focus on economics and explicitly said that I want citations and recent work from 2024-2025.  

This change in the prompts gives much more useful results.  As Gemini says, 

"Vertical greenhouses (or vertical farms) are technically proficient but continue to face significant economic hurdles, primarily high operating costs. While the market is experiencing rapid expansion, the industry is currently undergoing a "shakeout" where many early ventures that scaled too aggressively are failing, while more efficient, specialized operators are beginning to achieve profitability."  

They're very efficient, but have large energy costs, and only work well for leafy greens and--significantly--not for the high value veggies that grow on vines or are big and difficult to handle (think cantaloups).  ChatGPT pointed out that: 

"The business is highly price-sensitive to electricity: with retail/industrial rates spiking the energy component alone can reach ~$6.75/kg lettuce—destroying margin unless prices normalize or power is hedged or renewable."

 

Bottom line:  It's a tough world out there for putting high-tech / new-tech into difficult environments, and vertical greenhouses, while promising, still have the old problem of making money.  Economics never goes away, no matter how shiny the tech.  

SearchResearch Lessons 

1. As you dig deeper into a topic, modify your query / prompts to get more of what you need.  Pay attention!  As you saw, between my first and second prompts I realized that I needed more of a research topic focus (economics) AND that I wanted citations AND only results from the past 2 years.  That all went into my modified prompts.  

2. LLMs (Gemini, ChatGPT, Claude, etc.) work quite well for topics that call for broad ranging synthesis.  Yes, there are still errors of the types we've mentioned in previous posts.  But as Mike Caulfield helpfully points out in his post When wrong answers get you to the right information, you can often refine your question, ask a follow-up question, or use the citations given by the AI to lead you to useful resources. 

3. Be skeptical.  Be VERY skeptical of self-serving pronouncements by industry websites, articles, or promo pieces.  It's easy to find articles telling you that things are going incredibly well and that the market size will be $X billion in 5 years.  Be dubious, be skeptical.  Look to see how things are going now, and see if you can plausibly find a path from current conditions to a realistic future.   

 

Keep searching.