Ginger and I have had a difficult relationship.
It’s not because I tried to murder her, early on, shown above (Post G24-003, addendum). We’ve moved past that.
It’s not because her Tinder profile looked so different from her appearance in real life. I said I’d take her warts and all.
The problem is, she did not disclose that she likes it hot and dirty. And I’m just not able to deliver that kind of action. Not in my current situation.
Turns out, ginger thrives at a soil temperature of around 90F, with a minimum acceptable soil temperature of 70F.
Currently (mid-April) the dirt in my garden is around 50F. And there’s no way it’s going to get to 90F. Heck, it’s not even warm enough in my house to grow it. Which I think explains why, more than two months after I started down this path, my ginger plants are alive, but only a few inches tall.
This whole “grow ginger in a temperate climate” thing needs a re-think.
In a nutshell, my garden soil just doesn’t get hot enough, here in Zone 7. So, I’m going to make a planter designed to get the soil as warm as possible.
Maybe. This post is just Part 1, where I pin down the issue by (finally) looking up the actual data on soil temperature in my region.
Background
This year, on a whim, I decided to grow some ginger.
To be clear, ginger is a tropical plant. Worse, it’s a tropical plant with a 10-month growing season.
But the internet told me that it’s easy to grow it in a temperate climate. YouTube told me the same. Which makes it unanimous. So it must be true, right?
After toting a couple of trays of scraggly-looking ginger plants into and out of the house over the past month, it has finally dawned on me that, eh, maybe I got some bad advice somewhere along the line.
I now realize that:
1) Everybody who told me I could grow it in a cool climate actually lives in a warm climate. Australia, Arizona, and similar places. A mix of hot desert, tropical, and sub-tropical climates. So the folks I actually observe growing ginger, and being happy about it, all live where it’s very hot.
2) They all casually mention that, oh, by the way, ginger does well in pots, in cooler areas.
I finally put two and two together to realize that ginger is never going to grow adequately in a Virginia Zone 7 garden. The soil is just too cool.
Survive, yes. With enough work, you can get almost any plant to survive. For example, I have a lime tree that survives in my climate, via moving into and out of the garage all winter long. But thrive? In the dirt in my garden? That’s not looking promising.
Raised beds and garden soil temperature.
And bullshit.
Sometimes I am amazed by the things I’ll take at face value, just because everybody repeats them, and they seem reasonable.
That, rather than getting off my duff and doing the tiniest bit of actual investigation.
We all know that one of the advantages of raised garden beds is that they allow the soil to warm up faster in the spring. And we all know that because every site on the internet discussing raised garden beds repeats that.
In this case, the “investigation” involved sticking an instant-read thermometer a few inches into the dirt in my garden. This, from about a week ago:
- Lawn adjacent to raised beds: 49F
- Raised beds: ………………….. 49F to 50F
- Lawn under black plastic for two months: 52F
Maybe very tall raised beds result in markedly earlier warming of the soil. But short raised beds (around 1′ tall) do squat for spring soil temperature. Even the surface warming from covering the soil in black plastic was minimal.
Seems like my dirt is going to be the temperature it wants to be, and that’s that.
How did I ever miss the opportunity to obsessively measure the temperature of my garden soil?
But the fact is, I didn’t do that. So I’m going to have to take some generic soil temperature data and take some reasoned guesses.
This site discussing ground-source heat pumps is probably adequate, with the underlying data ultimately cited to Virginia Tech.
Source: Builditsolar.com, underlying data are from Virginia Tech.
The year-round average soil temperature where I live (which is also the deep down soil temperature) is around 57F. As shown above.
Source: Same as above, but highly simplified from the original diagram.
Near-surface soil temperatures ought to vary about 20F above and 20F below that average, as shown above. Right now (mid-April), that chart predicts that my near-surface soil temperature should be about 50F. Which is spot on. So let me now use the rest of the chart.
Based on the chart above, for my locale:
- It will be mid-June before the soil is warm enough to plant ginger outside (70F).
- I will have less than four months of soil temperature of 70F or higher.
- Soil temperatures will never get anywhere close to 90F.
The bottom line is that if I treat ginger as a houseplant until mid-June, then plant it in my garden, I might get some growth out of it. But my garden soil is never going hit temperatures at which ginger thrives.
Sure, I can grow ginger in my garden, in my climate. Just like the internet said.
I just can’t grow it very well.
Funny how nobody ever titled their video “how to expend enormous effort to grow a small amount of ginger in a temperate climate”. All I got were these subtle little hints, along the lines of “ginger does well in pots in cooler climates”.
How to expend enormous effort to grow a small amount of ginger in a temperate climate.
Now that my eyes have been opened, the obvious and sensible next step is to wish my ginger seedlings the best of luck.
As I toss them on the compost heap.
Instead, I’m going to look at what scraps of materials I have lying around and see if i can come up with a planter designed to overheat the soil. Which, even as I say that, sounds really stupid. But actually kind of makes sense, in this context.
You’ll have to stay tuned for the actual build.
Summary
Yes, you can grow ginger in a USDA Zone 7 temperate climate.
Nope, you can’t do it well, in the dirt, outdoors. The soil does not get warm enough for optimal growth.
This will almost certainly grow better in a pot than in the ground, because the soil in a pot will get a lot warmer. Hence the often-repeated hint that ginger does well in pots.
I’m still pondering what to do next. One obvious step is just to transplant to some planters, and wait. One step up from would be to put together a planter that’s designed to overheat the soil. That’s an interesting if somewhat oddball challenge.
Or maybe just to toss ginger into the compost heap. Because the basic notion that I can grow this well, in my garden, in my climate, now appears to be dead wrong.
Addendum: Ginger, meet Darwin
I guess the last straw was figuring out that it’s too cold in my house to grow ginger. I was OK with growing it as a house plant. But now I realize that I’m going to have to run electric heating pads indoors and/or build a greenhouse outdoors, just to prolong my relationship with ginger through mid-June . That’s just out of the question.
I considered going all-in for some sort of fancy planter design that would use solar heating to try to boost soil heat. But when looked up planter designs, it seems that nobody has any thoughts on building a planter designed to overheat the soil. That strongly suggests it’s a truly dumb idea, if you can’t even find a mention of it on the internet.
For soil warming, the sole option seems to be electric heating cables. If I’m not willing to run electric heat inside the house, that goes double for running it outside.
The ideal planter for ginger is broad and relatively shallow. Depending on the source, ginger needs between 8″ and 12″ of soil depth in a planter. But it needs horizontal room for the rhizome to grow. The combination of those factors means that an efficient planter for ginger is basically a flat, deep tray.
Given that, it’s more-or-less a fools’ errand to try to keep that heated above ambient temperatures. Even if I insulated the bottom and sides, the heat losses through the top would, in the long run, mean that the planter is going to match the average air temperature around it, plus or minus.
So I did the best for ginger that I could do. Above you see some 10″ deep crates, lined, filled with loose, well-draining potting soil, topped with about an inch of my finest kitchen-scrap compost. These now sit against a southeast-facing wall, and get sun from roughly solar 9 AM to solar 1 PM. The loose clear sheet on the front will eventually be taped up to provide a kind of double-insulated window effect along the sunward-facing edge.
By 5 PM, after a few hours in the shade, the soil in those planters is still around 80F. So maybe, just by luck, I may finally be giving ginger just what she needs.
I’ve now extended a simple irrigation setup to include these planters. That’s run off a timer, because I inevitably forget to water my potted plants. Beyond that, I’m going to put together some “box tops” out of radiant barrier material — simple caps to fit over these trays and reflect the heat back to the tray overnight. But that’s for tomorrow.
If ginger survives and prospers in that location, then it was meant to be. If not, I’ll chalk it up as a failed relationship, and move on to the next new thing.
