Get a handle on your microclimates

Practically the first thing a budding gardener (at least in the US) learns is their USDA winter hardiness zone. Based on average winter low temperatures, hardiness zones have many flaws but are still a very useful tool in figuring out what plants can and cannot survive your particular winters.

Right after learning about winter hardiness zones, we generally hear about microclimates – the idea that small precise locations within our garden may be, sometimes significantly, warmer or colder (or wetter or drier) than the surrounding climatic norms. The most pronounced producer of microclimates in most people’s gardens is their house – the sunny southern and western walls in particular can be markedly warmer than the rest of your yard. If you have hills, you also get frost pockets in low lying areas and warm south-facing hill sides.

But just how much warmer ARE your microclimates?  I used to live in a drafty, poorly insulated nearly 100 year old house which had VERY warm microclimates all around it because all the heat my furnace put out was rapidly leaking out into the outside world. Great for growing plants that normally wouldn’t take my winters, but oh, the heating bills! A modern, well insulated house leaks a lot less heat out into the garden. Over time in a garden, you can learn by trial and error just how far you can push growing tender plants in warm microclimates by planting things and watching them die or survive. But there is an easier and faster way to figure out your microclimates. Collect some actual data, getting firm numbers of how warm and cold different parts of your yard are.

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I’m heading into the first winter in a new garden, and getting ready to deploy a handful of cheap mechanical min-max thermometers. I’m placing one out in the open, the others against the south wall of a shed and other places I think should prove to be warm microclimates. Out they go, and after particularly cold weather – or just in the spring – I can check the different minimum temperatures they’ve recorded. A few degrees differences isn’t worth worrying about, but get to 10 degree differences, and you are talking a whole winter hardiness zone warmer.

In addition to comparing different locations in my garden, I also like to compare the actual temperatures I’m recording with those from local official weather stations (to do that, just go to www.weather.gov, enter your zip code, and then click “3 day history” on the right side of the screen). The zone map is created based on readings from weather stations like these, and if your particular yard is consistently showing temps warmer or colder than the local official readings (provided, of course, your thermometers are accurate), you should adjust your winter hardiness zone accordingly.

Finally, a min-max thermometer is a great way to test various winter protection methods. Tender plants can be insulated with a thick layer of leaves or (my favorite) cut conifer branches or even styrofoam boxes. How well do these protections work in your garden? Tuck a thermometer in with the plant before you cover it and then, come spring, check the minimum temperature it recorded against what you saw in the open air. Again, a difference of 10 degrees Fahrenheit corresponds to a whole winter hardiness zone warmer, giving you real actionable information about what you might be able to over-winter with the help of different sorts of insulation.

It is worth reiterating that minimum winter temperature is only one of a myriad of factors that go into winter hardiness, moisture, duration of cold, health of plants, and even summer heat matter as well, but winter lows are important, and it can be easily and precisely measured. So why not get some numbers on it so you can have a better idea of just what tender plants you can get away with in your various microclimates? A few thermometers is a lot cheaper than putting out a bunch of rare perennials and having them freeze out on you.

Cool plant of the day: Canary Bellflower

I’m such a plant nerd that a few years ago I actually decided to get Canarina canariensis, the Canary Bellflower, for no other reason than that it is one of the very few members of  the campanula family that has red-orange flowers instead of the usual purple-blue ones.

canarina 2
Canarina canariensis
A Platycodon showing much more typical coloration for this family
A Platycodon showing much more typical coloration for this family

Okay. Maybe that isn’t the most normal reason to add a plant to one’s garden, but I am VERY happy I did.

Canarina canariensis
Canarina canariensis

That color!

I’ll admit, it isn’t a plant that is particularly well adapted to life here in Michigan… as the latin name suggests (twice!) it is native to the Canary Islands off the West coast of Africa, where the climate is consistently dry, fairly cool, but never freezes. The summers are extremely dry, with a short rainy season in the winter. And the Canary bellflower has adapted to that by dying back to the thick fleshy roots in the summer, and then sending up the long trailing stems and flowers in the winter when the rains come.

That isn’t ideal for growing here in Michigan, but I’ve found I can get it to grow here pretty easily, actually. It is growing and blooming like crazy right now, and once it gets cold, I’ll move it inside, and let it dry out. As the soil dries, the plant goes dormant, so it can sit there patiently until spring and more settled weather when I can water and set it off into growth again. It works, and though it is a bit more work than most of the other plants I grow, it is worth it. I like looking at the lovely flowers, and speculating about the unique evolutionary path that caused this one genus to develop orange flowers while the rest of the family largely stuck with the tried-and-true purple.

One tree’s leaves… over 400 kinds of bacteria!

Okay… this bit of research just blew my mind.

Researchers took leaf samples from just ONE tree in Panama, and identified over 400 different kinds of bacteria making their home there. Sampling 57 different tree species, the total number of bacteria types ballooned to over 7,000. You can read more about the study here.

trees
A few trees. A nearly inconceivable number of microorgansims

 

That’s a lot. I love this kind of research because it just reinforces how LITTLE we know about this world we live in. Our world is filled with a massively diverse microbiome that we know virtually nothing about. Research is ongoing, and hopefully in the coming years we’ll begin to understand more about how these unseen organisms influence the world we live in. I’ll be fascinated to learn more.

In the mean time, any mention of microorganisms in a gardening context instantly raises questions of the efficacy of products containing (supposedly) beneficial fungi and/or bacteria for our soil. The huge, barely understood diversity of bacteria living in every aspect of our world is a good indication of why the research on adding specific microorganisms to soil generally show no impact, or only an impact in certain specific circumstances. This stuff is complex, and we’re just barely beginning to learn about it. Hopefully in the future we’ll begin to learn how to manipulate the microorganisms that live with our plants, but I wouldn’t expect it to happen over night. Right now, I’m just following the basic rule of adding organic matter to my soil to make a good home for the organisms that live there, and following the research as it opens a window to this unseen world all around us.

 

Cross-pollination making you cross?

No, your cucumbers have not hybridized with your melons.

I’ve been fielding different versions of the same question a LOT lately.
Three different people have sent pictures of “cucumelons” telling me they planted cucumbers next to their melons, and now the cucumbers look strange, so they’re concerned that they have cross pollinated with the melons. One person planted what was supposed to be a red raspberry next to their yellow raspberry, but the new plant is producing yellow fruit, so they think that it must be cross pollinating with their yellow plant, causing the fruits to turn yellow. Not to mention similar queries about tomatoes, peppers, and watermelons. It seems like every time a piece of produce turns out looking differently than what people expect, they blame pollen from the plant next to it.

I’m sure the highly educated readers of The Garden Professors know this already, but to clarify, there is a very simple reason why you don’t need to worry about one plant pollinating another plant and changing the quality of your produce UNLESS you are planning on saving seeds to grow for the next year.

When a flower is pollinated and starts developing into a fruit full of seeds, it is only the seeds themselves that combine the genetics of the two parents to develop into something new. Everything else – the flesh of a tomato, or cucumber or melon or raspberry – is produced solely by the mother plant, and the daddy of those seeds inside doesn’t matter a bit. Think about when a woman is pregnant… the identity of the father of the child inside her doesn’t change the character of the skin of her belly.

If you want to save seeds of your plant for next year, it is another matter, and you should be sure to isolate or (better yet) hand pollinate different varieties of the same species from each other to make sure they don’t hybridize unintentionally. You still don’t need to worry about your cucumbers and melons, however – they won’t hybridize by chance in your garden. If a plant doesn’t produce the right colored fruit or flower, most likely it was just mislabeled at the nursery. Grow a strange looking cucumber, chances are it was left on the plant too long. Cucumbers are harvested and eaten when young and immature, leave them too long and they get… strange looking. No need to blame it on the melons next to them.

There IS one exception to this, one common plant in the garden where the source of pollen makes a huge difference in what you harvest: Corn. Corn is the exception because what we’re eating is the seed itself, not the fruit produced by the mother plant surrounding the seed. That’s why if your sweet corn gets a dose of pollen from the field corn the farmer is grown next door, it comes out starchy and not sweet.

It also makes breeding colorful corn for fall decorations REALLY fun… Because when you see a multicolored ears of corn like this from my garden last year:

multicolored corn
You can carefully pick out just the seeds showing the colors you like best, say the palest blues and pinks, sow them together the next year, and get something looking like this:

pink and blue corn
Or plant all the darkest kernels together and get this:

black corn