Today it was 61 degrees out, woohoo, finally, after such a cold cold Winter & Spring. Of course, tommorow it starts getting cold again, but today was nice, and I spied my first flower.
I was out in the garden doing what you should do this time of year, which is prune trees if they need to be pruned, and clean up old spent perennials from last year, getting the garden ready for new growth. You prune trees now because they store all their energy in their roots while dormant, so by cutting off dormant limbs you’re not cutting out any of the tree’s stored energy – but then you wait until the end of Winter to do it because that way the wound is open for longer. Once the sap starts flowing the tree will close it up, and all that sap, since it has fewer limbs to go into, will push up and out and generate a lot of new growth.
So while out doing this and pruning my bald cypress I noticed a little crocus poking out and I was thoroughly surprised, the snow only just melted, and in fact, in shady areas, it still hasn’t melted. We’ve got a few inches still, and the ground only just unfroze too in most areas, but I guess the crocuses were as anxious for Spring as me.
My first flower is always a crocus, but this year it is purple.
In 2012, hah, I remember 2012, a warm Spring, the end of March already had fruit trees blooming. My first flower was a yellow crocus on March 10th. In 2011 it was the same flower, on the 15th, in 2010 on the 16th, and in 2009 also on the 15th. This is the Michigan misery metric I use, the date of the first bloom dictates how miserable winter has been. It looks like I forgot to check in 2013.
So this year was slightly different, a purple one was first, and it was in a new location from prior first blooms, and of course, it was practically April before it showed up.
Spring is a time of optimism, of renewal, of growth, well, normally. Unless you live in Michigan under the specter of the polar vortex.
This winter has been horrible, absolutely horrible. I normally am not one to get worn down spiritually by the winter, but I have this time. I hate it here, I absolutely hate it. It hasn’t even been a fun winter, where you can go out sledding, or skiing, or building a snow man. It has been too cold even for any of that. We’ve had more days below 0 than above freezing. I’m sure some plants will have perished by the time Spring rolls around, even my dwarf alberta spruces (the key word being Alberta, a place I’m told is colder than Michigan) are showing significant winter burn.
But I just got back from Florida (yay!) and the vitamin D did me a little good, so I’m feeling more optimistic… so much so that despite the feet of snow still lingering on the ground, I’ve started seeds. No, not outdoors, but indoors in trays. In 6 weeks we won’t be past any frost danger, especially this year unless that god forsaken polar vortex goes away, but I could put out cold hardy plants like kale and spinach and beets, so I’ve planted them, and I even planted tomatoes and peppers too, though they will have to stay indoors longer.
But I hate Michigan weather, and I cannot wait to move, and I am moving. I probably only have one winter left here and I’m moving to Tennessee, wonderful Tennessee, where did you know the appropriate planting time for trees is February? Yes, February, when Michigan is still buried in snow, you can plant trees in Tennessee. So I had some planted. A couple years ago I bought some land, we recently had the home site cleared, and we hope to start construction soon, but I had my contractor go up and plant 14 trees for me. 8 apples, two pears, two plums, and two apricots. This will be my orchard.
I could have waited, and planted trees once I move down there, but I love home grown produce, I love being able to go out and pick an apple or pear, and I’d miss not being able to do that when we move. In my opinion every home should have an apple tree, and I certainly wanted many, but it takes time for them to reach fruit bearing size. So I had them planted now. They won’t bear fruit this year, they won’t bear fruit in 2015, but it is possible they’ll bear fruit in 2016, the first full year we’d live down there. By planting them now I’m getting a head start on that growth and I’ll be without fruit for a shorter period of time. If you’ve been thinking about planting an apple tree or something, stop thinking and just do it, they need time to grow, time you can’t get back if you miss the opportunity. I got all mine from Stark Bros, and if you need one variety, pick a Honeycrisp, but you should do it. If you have a 4′ x 4′ space with sun in your yard, you should have an apple tree. You can buy them dwarf sized, so they’ll never get large (which also makes them easier to harvest from). Carpe diem.
I’m really happy to be moving, in addition to more land so I can plant more trees, I’ll have room for a massive Martha Stewart sized vegetable garden, room for chickens and maybe even pigs or goats, and… dun dun dun… a greenhouse! I cannot wait until I have a greenhouse. Right now I don’t even have a south facing window. Indoor growing or seed starting is difficult. I am restricted to a small ledge by a large east facing window in the kitchen. With a greenhouse (and it’ll be over 300 sq/ft), I get giddy thinking about all the seeds I’ll be able to start, the plants I’ll be able to grow year round. Tennessee also has a much longer growing season than Michigan which means I’ll get more crops in, and all my trees and ornamentals should put on more growth each year, getting bigger faster. Zone 7, so many more plants I can grow in Zone 7 than Zone 5. Maybe even hardy varieties of olive or agave, I can’t wait.February 23rd, 2014
In December, right before Christmas we were hit by a major ice storm, the worst in decades. People at the power company said it was the worst they could remember. We didn’t lose power, luckily, but people all over our town did, some for as long as 10 days (into January). Major commercial areas lost power, more traffic lights were off than were working, downed power lines were everywhere, some left for days or weeks, because they didn’t have the man power to fix them all. This isn’t Georgia either, this is Michigan, we have tons of crews and plows and salt and people trained for this sort of weather, and it still took weeks.
Then because of the polar vortex the ice stuck on the trees for weeks, and if not for an early January warmup (above freezing for maybe 2 days, woohoo!) it’d still be there. Luckily we didn’t have much wind or it would have been worse, with even more trees falling (as it is, every single yard had a branch in it). To this day I’m unable to take down my Christmas lights because they’re frozen in thick ice (now topped with snow). Likewise branches still litter curbsides everywhere around town as crews couldn’t get them picked up before the snow entombed them.
It was beautiful, peaceful, annoying, and dangerous all at once. I went outside, carefully, and it was quiet, and I live on a 4 lane road, but no one was out, not even the sound of a distant snowblower, it was still, like in the country where I grew up, and then CRACK, or BANG. You’d head or see branches fall, it was like the opening day of deer season out there. If this happens to you, be careful, and do not go outside, and if you do do not walk or stand underneath trees.
It made for a very white Christmas, and it was pretty, but thousands of people spent the holidays in a hotel, and many trees were lost.
For your garden there isn’t much you can do. For heavy, wet snows, that bend branches and bushes to the ground, brushing the snow off can help, but you can’t brush ice off, so you sort of just have to bear it, and take any damage that is dished out.
I’m a big science geek and so when I was offered a free copy of A Garden of Marvels: How We Discovered that Flowers Have Sex, Leaves Eat Air, and Other Secrets of Plants by Ruth Kassinger I quickly accepted, and I’m glad I did.
My first job was bagging groceries, however my second job was working in a research lab at Michigan State University studying the genetics of arabidopsis thaliana trying to identify phenotypes that produce increased seed oil. So I’ve always been interested in some of the science behind plants, though I’ve never taken a botany or horticulture class, and even left the world of biotechnology behind for computers while in school, not because of lack of interest though, but because it isn’t as glamorous as Jurassic Park makes it sound. Imagine harvesting and cataloging millions of seeds and then analyzing their oil content, it is cool in the abstract, but very tedious to actually sit down and do. There is a passage in the book about petunia breeding where the author remarks upon rows and rows of hundreds of plants grown just to see what their flowers will look like, with almost all of them destined to be composted, and I definitely had some flashbacks.
A Garden of Marvels takes the reader on a journey through botany, and some of the history of it. I also happen to like history so it suited me very well. There is one section where I think the author gets a little too far into history and away from the plants (following a tangent dealing with medieval study of human anatomy), but throughout the rest of the book the author is excellent. It is hard to talk about modern plant science though without hitting on some perhaps controversial and or political topics, but the author never comes off as preachy or advocating any one position.
Rather than a single narrative the book is a series of vignettes about specific topics in the plant kingdom, from how we got plants in the first place, to how we learned that plants produce oxygen, to how we learned what the purpose of flowers were (it may seem obvious now, but apparently back then there was a lot of confusion). Mostly the narrative ties together modern science with ancient developments. For instance you may learn at one point how there are two different photosynthetic pathways, C3, and C4, and how they came to be, you’ll also learn scientists are trying to develop rice that follows the more efficient C4 pathway to held the world deal with hunger. There is also a nice whole section about the evolution of plant life dealing with the transition from gymnosperms to angiosperms and how that happened, some of which I touched in my recent post about a dinosaur garden. There is also a section about the booming business of growing tomatoes in Ontario, and the farmer there who heats his greenhouse by growing, and burning, an ancient grass you might have in your garden (I do – and you should if you don’t, it is a cool plant).
So gardeners, if you’re looking for a good read, I recommend the book. Yay science!February 8th, 2014
Your landscape can be beautiful, your landscape can feed you, but your landscape can also protect you. Much like a well trained dog can be both a friend and a security system, your yard and garden can serve double duty too.
First Do No Harm
The first step to deterring burglars and other miscreants with your landscaping is to make sure you’re not doing anything to encourage them. Large shrubs or bushes that hide your windows or doors, allowing a burglar to work on them out of view, are a big no-no.
You should also keep a well maintained yard, believe it or not, a well maintained yard is a deterrent, criminals see a well maintained yard and think that you obviously take pride in ownership and are more likely to have well constructed locks or other security devices.
Fencing your yard is also a good idea, however make sure you’re not giving any bad guys a boost. So you have a 6 ft fence surrounding your back yard, do you have a grill, trash can, or raised planter right by the fence providing the would be interloper a leg up? If so, move it. Otherwise you’re doing the equivalent of leaving a ladder propped up against your house under a window (also, never leave ladders out, that is just asking for trouble).
So clean your yard, don’t give thiefs concealment, and don’t leave any tools out they might be able to use to climb in or over your defenses.
When you’re running from a bear…
Old story, when running from a bear, you don’t have to be faster than the bear, you just have to be faster than the other people you’re with. There is absolutely nothing your landscaping alone can do if a person is determined to break into your house, your goal is to make your house less attractive as a crime of opportunity than your neighbor.
The best way to do this, is with thorns. Now above I said you don’t want high bushes up near your windows and doors, and that is true, but lower bushes, especially thorny ones, are a good idea. You can build a hedge 5 or so feet off the walls of your house or your windows, not tall enough to hide the windows, but tall enough that you cannot step over it. You can also plant low bushes right up against your house near your windows, just keep them pruned so they don’t get too high, and really plant them right up against the house so there is no room to wiggle between the thorns and the siding.
Roses are an excellent choice, with pruning they stay open and won’t hide anything, their canes get decently thick and are not easily bent out of the way, and the thorns can be really, really, wicked. Some rose varieties are bread to have minimal thorns, but there are some varieties that are covered in huge thorns, to the point where you can’t even see the canes.
A plant I like and have blogged about before is barberry. I actually use both barberry and roses in my landscape for security purposes. Barberry is not as stiff as a rose would be, but it grows very very very bushy, and the thorns, while not as strong, do definitely hurt. They’re not as visible though, so might not deter someone until they are felt. If you could grow a barberry hedge around and under your windows, no burglar is going to want to wade through it to try to pry that window open. The plants are also very attractive.
Blackberry or boysenberry thorns I find to be particularly insidious, way stronger than raspberry thorns. Of course there are thornless varieties, so make sure you aren’t buy them, they also need supports so they don’t grow too low to the ground. But with these you can have your security and eat it too. Because they spread rapidly if there is say a short strip of land between your house and a walkway, that is actually a really good place to grow such bramble berries because they’re kept contained by your house on one side and the walkway on the other.
There are many woody shrubs or small trees that have wicked thorns, usually “thorn” is in the name. Such as blackthorn (Europe, originally), spiny hackberry (Texas), and my favorite, Hawthorn (Crataegus), native all over in the northern hemisphere, with hard sharp thorns up to 4 inches long. In Old English “haw” meant hedge, so you can see this plant has been used for protection for a long time. It can grow as a shrub or small tree, and can be pruned into a hedge (wear leather, please). It is also largely edible, the fruits and leaves can both be eaten (maybe that’s why the tree evolved such elaborate defenses). Hawthorn is one of those plants you could use as a very effective living fence if you have the time to let to grow and the time to maintain the pruning.December 22nd, 2013
Self-watering planters are a boon to many gardeners and have taken the gardening industry by storm in a variety of forms. Either for people who lack the room to garden in the ground, or people who lack the time for regular watering, they work great. But, how do they work, and could you make one yourself?
Do you remember the word capillary action from school? Or perhaps just wicking? This is why if you dip a piece of paper in water, the water will climb the paper. It also works with soil, and this principle is behind self-watering containers.
Essentially you have two containers in one, the lower container is a water reservoir holding potentially gallons of water, the upper container holds your soil, and it has to specifically be potting mix, regular old dirt doesn’t wick water nearly as well (nor is it good for containers anyways, always use potting mix in containers). There is a mesh connection between the two allowing some soil to get wet. Eventually your plant’s roots will reach the water, but until then the soil will wick moisture up to them. Depending on the size of your reservoir (which also needs an overflow hole so as to not get too wet) you could go weeks without watering. You can also hook a series of containers up to a rain barrel for automatic watering. A container garden that takes care of itself. To add water to the reservoir there is often a pipe or a hole for easy access. You don’t pour water through the soil to reach it, you have direct access to the reservoir.
There are however some downsides to self watering containers. Some plants do not like perpetually damp soil, the soil in a self watering pot will never completely dry out and so those plants may not be happy. Also, depending on how it is designed, there can be an issue with providing mosquitoes an ideal breeding ground (you really need to find one with some sort of cap over the reservoir access and overflow opening). When using a self watering container you directly water the roots, not the foliage so you lose out on opportunities for foliar feeding, however by keeping the leaves dry you also reduce the risk of fungal infections.
There are many types of self watering containers you can buy, but most work on this same concept. One I have is slightly different though. The Octopot uses a special bag made out of wicking fiber. I think this is a superior construction because it pulls water from the reservoir all the way up the sides of the soil, resulting in better moisture coverage in my opinion. With caps over all the ports it also is no friend to mosquitoes and includes a little water level indicator so you can easily see if it needs more water or not. One downside of it is that it is nearly impossible to move when full of water, 6 gallons plus soil is quite heavy, so either pick a spot and stick to it, or put it on a little plant dolly (little square with 4 caster wheels on it, so you can roll your containers around).
The Octopot is obviously utilitarian in appearance and so lends itself more to functional, ie edible, gardening, than ornamentals. However there are some very attractive self watering containers out there as well if you wanted something more presentable for the front walk that you could put flowers in.
You can also make your own. You simply need two plastic containers of roughly equal size. Recycling is best so think of what you use frequently. Do you get those big plastic pails of kitty litter? Ice melt salt? Do you have old 5 gallon buckets from Home Depot lying around? all could be used, though wash them out good if they were used to store yucky things. If you know someone in the food industry you may have access to old used vats of food grade plastic that once held salad dressing or something, that’d be great, you just need two of the same size that can be nested inside each other.
The bottom one you cut a hole in the side 4-6 inches up to act as an overflow, the top one you cut a hole in the bottom and line it with some sort of perforated material, then another hole in which you insert a pipe that leads to the top above the rim. Then you simply fill with soil. It won’t have the fancier features of the Octopot, but it’d get the job done. Here is a photo tutorial on building large ones out of plastic storage containers.November 8th, 2013
It is November, you’ve likely already put your garden away, or you will soon. I’ve personally been procrastinating. Outside maybe the frost has already gotten your herbs, maybe not, maybe you live in Florida and it never will, most of us though have to say goodbye at some point to your fresh herbs from the garden, but that is okay, because you can continue reaping the bounty in the winter if you simply dry your herbs.
Not all herbs take well to drying, basil loses much of its flavor, though it still has some flavor, it isn’t very good. Tarragon ends up practically tasteless when dried. However, some herbs do quite well being dried. Rosemary, thyme, oregano, and sage all dry quite well, though why anyone would want sage is another matter (its yucky!).
Anyone who has bought herbs at the store knows how expensive they are, fresh or dry, and at this time of year why sacrifice that large rosemary shrub you planted in the Spring to the gods of Winter? Cut it down, it is going to die anyway (if you’re north of zone 7) and dry it, you’ll have all the rosemary you need. Your thyme and oregano may make it through the winter, but not without damage, so cut liberally from them too, and bring it all inside.
Drying herbs is the easiest thing in the world. You can use a fancy food dehydrator, I have one and it is great for making apple chips, or beet chips, or kale chips, or drying out hot peppers for making powder seasonings, but it isn’t necessary. If you’ve ever dried flowers before you know how to dry herbs. Just pick a warm spot out of direct sunlight and out of the way, bundle your herbs up with some twice, and hang them upside down. Give it a few weeks, when they’re brittle, they’re done.
You can leave them as is, picking off the leaves or needles as needed, or you can pluck the stems now and store them loose in canisters or jars. The volatile oils in the plants that give them their flavors will degrade eventually, you’ll help slow that process down by keeping them out of direct sunlight, in a sealed container, but one with some extra air in it (glass jars are better than plastic bags). Then enjoy them to flavor your cooking until your garden is growing again next summer, it is hard to beat something so cheap and easy.September 29th, 2013
This is prime time for apple harvesting, the earliest varieties would have been ready in August, the majority in September, and even then some into October, and the latest in November. I was really excited this year to get the first good apple harvest from my apple trees. They should have been big enough to produce last year, but an inopportune cold snap decimated my apple trees in the spring, getting down to below 20 when the flowers had just opened, the entire state of Michigan lost something like 98% of the apple harvest.
I have a mere two producing apple trees, a honeycrisp, which I’ve since harvested, and a yellow delicious, which I will harvest next week. If I had to recommend only one tree, I would recommend the honeycrisp, it is an excellent apple, produces well, and is good is pretty much all apple applications from pies to cider. But I tell you what, even 1 semidwarf apple tree can produce a lot of apples. Even without spraying any chemicals, even with squirrels and whatever else stealing a few, you’ll get a lot of apples. So what do you do?
The first important issue when harvesting apples is deciding when. You need to know what apple type you have, and then you can use the Internet to figure out when it ripens in your area. Commercial growers will actually pull apples and test them for sugar content, you can try taste testing or just go by historic averages. Of course, if you don’t know the variety you have, you’ll have to do taste testing. Color is not a reliable indicator of ripeness, many apples will change color long after they’re ripe, or be ripe regardless of color. Color on many apples is most influenced by sun exposure, which has more to do with where the apple sits on the branch, not ripeness.
Assuming you’re harvesting at the right time the second big issue is, who cares about funky, damaged, or spotted fruit? Did you think every apple you grew would be round and shiny and perfect like the supermarket ones? Well, for one, those are usually sprayed for insects, and you probably didn’t do that. Even if organic gardening isn’t your thing, no one likes sitting down underneath a tree and spraying a chemical upwards, even something organic like neem oil is going to fall back down in your face and whatnot, plus, good luck reaching the top branches for good coverage. No, accept the fact that your apple tree will produce some funky apples. Maybe some will have even fallen and been damaged.
The fact is, all tree produce funky apples, they’re just sorted at the orchard. The best apples are packed individually, are big and beautiful, and sold to you for $4 per pound. Lesser quality ones are bagged and sold that way, even lesser quality ones are turned into things like apple pie filling, and then the worst are either apple sauce or apple cider. Then whatever is left is turned into compost or bacon (courtesy of pigs). So on your tree you’ll likely have a few big shiny apples that are excellent for eating out of hand, but you’ll also have some misshapen, spotted, runty, or damaged ones, but don’t throw them out! When life gives you funky apples, make apple sauce.
If you’ve never made apple sauce before it is really easy, especially if you have a KitchenAid Stand Mixer. If you have a mixer you just cut off any damaged parts from the apples, minor insect damage can be kept, but any large gashes or bruises or anything that shows rot on it should be cut off, yes, a half rotted apple is half a usable apple, then toss it all, cores, stems, and peels, whole apples, into a big big stock pot, and cook it until the apples are mush. Then you run it through the food mill attachment attached to your stand mixer (if you don’t have the food mill attachment, you can buy it here. It is probably one of the greatest devices ever invented, it makes making applesauce, tomato sauce, and lots of other things a cinch). This attachment perfectly can take a whole apple and spit sauce out one end and core/seed/peel/stem out the other. It is magical, wonderful, and saves hours of work.
If you do not have a mixer (or other sort of manual or automatic food mill) then you need to peel, core, and chop every apple prior to cooking it in the pot. This can take hours, and what is more is I think you end up with lower quality sauce. When you cook the whole apple you extra a lot of the goodness from the peels and cores, like additional pectin (which makes the sauce thicker and improves mouth feel), and nutrients in the peel. I really cannot recommend the Kitchenaid route enough, it is like magic!
Once you have your sauce taste it and see if you want to add anything. You can add sugar, but it isn’t necessary for preservation. You can also add spices like cinnamon or nutmeg. Then make sure you keep it heated and simply can it using a pressure or boiling water bath canner. You’ll want to process it for 15 minutes, leave at least a half inch of headspace in each jar, and make sure you keep the sauce hot for packing it in the jars, yes, if it bubbles, and gets on your skin, it is like napalm, but it needs to be hot for loading. If you do not know how to can food I talk about it a little in this post and there are many Internet resources that explain it as well.
I don’t know if it is merely psychological bias, but I think the sauce I made from my honeycrisp apples was just about the best I ever had, unsweetened even. Could it have been the added pectin from cooking whole apples? Maybe. The fact that I used a premium apple like honeycrisp? Perhaps. I just know, it is delicious, and good thing, because I have around 24 pints of it now. I also know exactly what is in it, and exactly what was on the apples (nothing but rain and sunshine).
I also made 1 pie and filled both crisper drawers in the fridge to the top with apples to eat out of hand, plus the ones that never made it to the fridge. All of this from 1 tree which I paid $20 for and planted a few years ago. Around here, nice big honeycrisp apples are $3 or $4 a pound at the grocery store (more expensive than any other apple type). So the first 5 big apples I ate made back my investment on the tree, and the rest is profit. In my not so humble opinion, every yard in the country should have an apple tree, and if you don’t much care about the variety you can get them for less. Troll garden centers in the fall when things go on clearance. I’ve found a tree for as little as $6 before.
I planted grape vines along my fence I don’t even know how many years ago, but I’ve never really gotten grapes from them, every year, before they ripen, the birds eat them. I have a seedless concord grape vine and a green seedless table grape of a variety I do not recall, but I never got grapes from them. It was an endless source of frustration.
Granted I also don’t prune them as well as I should for true grape production as you’d find in a vineyard. My garden is a little too crowded for the spacing required for that, or the access I’d need to walk over and prune them, so production isn’t as high as it could be, but I still never got any grapes.
This year I vowed to do something about that though. In my research I saw that some vineyards would use bird netting over the entire vine, and I really didn’t have the space for that (the vine is along my fence, and I also have trees, shrubs, and other plantings brushing up my fence in spots, so wrapping the whole fence in netting would be very difficult). Plus I thought that smushing all the leaves and whatnot together would limit overall plant vigor and could induce fungal issues.
I hit upon the idea of getting mesh/net bags and putting each grape bundle, while it was still immature, in a bag to protect it. This was fairly tedious, it took a couple hours, and it wouldn’t work for a very large scale grower, but it worked for me. So this year, finally, I got grapes. Not much, but some. I need to do better with pruning next year to try to increase production.
I ended up buying three different types of bags. I was originally searching for green mesh net bags, like the sort of nylon mesh you’d buy maybe onions or oranges wrapped in, that is usually red though, and I could find lots of red, but I wanted it to blend into the landscape more and so I searched for green. I did eventually find some simple ones like that on eBay from the UK and had them shipped in. I could find of course, single count mesh bags in green, purple, or any color I wanted, but when I needed 100 I needed something cheap and in bulk. These were the net style nylon bags with no drawstring or closing mechanism, so they weren’t entirely idea, they were also larger than the average cluster of grapes by quite a bit. I also bounght some drawstring ones from Alibaba Express. This is sorta like an eBay site for Chinese manufacturers, all told it was a very safe transaction, the money was held in escrow until my goods arrived so I was assured of not being ripped off. I would recommend it. These bags, with drawstrings, were really easy to put up on the vines, and at 34 cents each they were affordable. Finally I got some red polypropylene net bags on eBay as well. Red didn’t blend into the background, but it made it easier to find and harvest the grapes afterwards, they were also really cheap, 2.3 cents each. What I ended up doing is using the green bags on the outside of my fence where the neighbors could see them, and the red bags on the inside where only I could see them.
It isn’t a perfect system, and I still want to tour some vineyards sometime to see how the big boys keep the birds away, but I got grapes for the first time this year, and that makes me happy.July 30th, 2013
Spinach and beets are two of my favorite crops to grow in my relatively limited vegetable gardening space, but this year they just got infested with spinach leaf miners (probably because I have too little room to rotate crops and I grow them every year). I ended up getting very little spinach harvest, I hate those little things.
Leaf miner damage can often be confused for other problems. It can resemble to the uninitiated perhaps slug damage, or even a fungal infection. It is not these things. The key identifier of leaf miner damage is that the leaf is eaten on the inside, but the outside is fine, so you end up with a white wilty area on the leaf. You can also verify it by inspecting the bottom of the leaves and looking for little white eggs, usually in clusters of two or three.
The leaf miner is a species of insect, with the adult form like a small fly. They lay eggs on the undersides of certain species of plant (each species of insect has a preferred species of plant), the eggs hatch, the hatchling burrows into the leaf and then mines the inside of the leaf for food, leaving behind poop (the little black specs you then see inside the leaf) and not much else. For a leaf crop like spinach or chard, this obviously hurts. It even hurts for beets because we can eat those leaves too (and I do) and obviously losing leaves reduces plant vigor.
When full the larva, now like little grubs, tunnel out, drop into the soil, tunnel down, pupate, and emerge later as adult flies.
Controlling these pests is difficult. You can spray with neem oil, but it hardly works, and you have to get on the underside of the leaves, which is difficult. The main problem is the critter lives inside your plant, so topical sprays will no work unless you get it at that point of hatching. You can inspect all your plants to remove eggs before they hatch, but good luck with that. You can use floating row covers, but they need to be small enough to stop the small flies and they don’t help when the flies are emerging from soil at the plant’s base. It is almost the perfect pest, living inside your plant and then the soil directly underneath it.
The best controls are crop rotation and, if you have the time, daily inspections of your crop. When you spot the first signs of leaf miner damage, remove the leaf, and put it in a sealed garbage container (do not compost it, or the fly might just live). If you can, miraculously, cull an entire generation of leaf miners prior to them fully developing inside the leaves you might just save the harvest, but any leaf you remove will reduce the future population of the critters.
They overwinter in the soil, so intense cultivation in late fall and early spring may disrupt them there as well.
Spinach and beets/chard are related so they eat both plants, but they prefer spinach, and indeed this particular species in my garden is known as the spinach leaf miner. The interesting thing is, to me, that my beets seem to recover after I pull my spinach once it bolts in summer, the flies don’t seem to do as well with only beets to eat. Next year I plan to just not grow spinach, I will still grow beets. I will cultivate heavily in fall and spring, and I will try to be diligent about checking the leaves earlier for the first generation of these pests, and maybe reduce their population.