284 Ranking Garden Mulches. Fall Worm Bin Care.

Show Transcript

284 TRANSCRIPT Mulches, Worms

Farmer Fred  0:00

Garden Basics with Farmer Fred is brought to you by Smart Pots, the original lightweight, long lasting fabric plant container. It's made in the USA. Visit SmartPots.com slash Fred for more information and a special discount, that's SmartPots.com/Fred.

Welcome to the Garden Basics with Farmer Fred podcast. If you're just a beginning gardener or you want good gardening information, you've come to the right spot.

Farmer Fred

Today’s episode begins quite simply as an answer to a question, how do you plant seeds in a garden bed full of mulch? Good question. America’s favorite retired college horticultural professor, Debbie Flower, and I quickly veered into a very scenic bypass - as is our custom. This time: we ranked garden mulches from best to worst. If you want to know the best products to use for a mulch - and the ones to avoid - you’ll want to listen. And then we talk with Master Gardener Susan Muckey - the self-proclaimed worm whisperer - and she shares with us what the worms in your worm bin are telling her about what they want in order to be happy, this fall and winter.

Mulches and worm castings! Two topics that brighten up my gardening heart.

It’s all right here, in episode number 284, Mulches Ranked from Best to Worst. Fall Worm Bin Care.

We’re podcasting from Barking Dog Studios here in the beautiful Abutilon Jungle in Suburban Purgatory. It’s the Garden Basics with Farmer Fred podcast, brought to you today by Smart Pots, and Dave Wilson Nursery. Let’s go!

MULCHES RANKED FROM BEST TO WORST

Farmer Fred

We are answering your garden questions here on the Garden Basics podcast, I always bring in the chief answerer, America's favorite retired college horticultural Professor. Debbie Flower is here. Patty in Petaluma has a question for us.

Patty in Petaluma  1:59

Hey, Farmer Fred and Debbie Flower. This is Patty. I live in Petaluma, California.USDA Zone 9b. Quick question. I grow mostly in raised beds. But I also grow mostly from seed. I really want to mulch, but how will those seeds sprout through the mulch? Thank you.

Farmer Fred  2:18

Petaluma is in Sonoma County here in Northern California. And Patty is growing mostly in raised beds, and she grows from seed. And that's really great. But she wants to use mulch. But how will those seeds sprout through the mulch, she asks. Well, it's a fair question. Because this confuses me. Some seeds need light. But if they're buried, down in the soil, but not by much, how do they sprout?

Debbie Flower  2:44

Some seeds need light, some seeds need darkness, and some are kind of in the middle. And you can research that. Or, if these are seeds in a commercial seed packet, they will tell you on the package if the seeds need light to germinate. And that means you put them on the surface of the soil. And so they receive light, and you hope they don't dry out. And that can be tricky.

Farmer Fred  3:05

Yeah. And if they call to be covered, you don't want to cover it by too much. So would that be the reason that mulch on top of a new seed bed may not be a good idea?

Debbie Flower  3:16

Yes. Well, there are two reasons. One, if it may result in the seed being too deep underneath media and mulch, or it may be if it's depending on what the mulch is made of. The mulch itself may be too heavy. And the baby plants that grow from the seed can't push the heavy mulch out of the way.

Farmer Fred  3:35

The plant doesn't come out of the ground like Popeye, after a can of spinach. No.  I mulch on my beds. The garden beds spend the fall and winter with shredded leaves on top of the bed. Come late winter, early spring and I want to plant from seed in the bed, I usually just clear off a little row, just a few inches wide. And I plant in that row.

Debbie Flower  3:58

Right. And so you move the mulch away or if you haven't applied yet, you don't apply it exactly where you put the seed. The one thing you can use is vermiculite.

Farmer Fred  4:09

Oh, to cover the seed. But not too thickly, I would imagine.

Debbie Flower  4:13

Well, I've had students do it thicker than I thought was a good idea. Kind of maybe quarter to a half an inch, so you can't see the soil at all. And the seeds have come up anyway. And they were seeds that need light. That's one of the beauties of vermiculite. It reflects light.

Farmer Fred  4:30

Would you only use vermiculite, then, for those seeds that need light?

Debbie Flower  4:33

I use it on everything because it traps moisture. It holds moisture. The seed has to remain wet, once it starts to germinate. Even if you can't see that it's germinating, stuff is going on inside that seed. If it dries out, it dies. And so vermiculite holds an extra amount of moisture over the seed and without drowning the seed. And also, if the seed needs light, it provides that or allows light to get to the seed.

Farmer Fred  5:01

We can make it easy for you, too. If you want to do that, you can just buy a commercial seed starting mix and cover that seed with a very thin layer. Right?

Debbie Flower  5:10

For me the beauty of vermiculite is I can see it. So I know where the seeds are. Whereas with a seed starting mix, it would probably blend into my soil in my raised bed and I wouldn't know the exact location of the seed.

Farmer Fred  5:23

Well, you're not going to know it anyway, after you water it in.

Debbie Flower  5:27

The vermiculite is visible, not forever, but for generally until the seed germinates.

Farmer Fred  5:33

Now, the question is, what sort of mulch should you use? I mean, you're gonna move that mulch back near the plant after it is strong enough and taller than the mulch, right? And you would still not touch that plant with the mulch, right? Just bring it nearby. And it'll live happily ever after. We can hope. But it depends on the mulch.  Recently, the Sacramento Tree Foundation conducted a little experiment, ranking mulch materials from best to worst. And this is talking about mulching established plants, especially trees and shrubs. After all, this is the Tree Foundation. So they're looking at trees and shrubs, they're looking to employ a mulch to do what mulch does best. It increases soil moisture content. By modifying the soil structure, it increases the porosity of the soil, it decreases salt buildup in the plant root zone, it adds organic matter to the soil as the mulch breaks down, thus increasing the nutrient content. It decreases soil borne diseases. And it increases the growth of trees and other woody perennials that are planted under them. So there's a lot of good reasons for using mulch because of water and soil temperature and weed control. Things like that.  And when you are adding mulch to the soil, you're just adding it to the top of the soil.

Debbie Flower  6:57

Right you are. You're noticing it in the definition of mulches. It's on the surface. An amendment is something that you mix in. Amendments are not what we're not talking about. We’re talking about a mulch.

Farmer Fred  7:09

Explain why you don't want to incorporate mulch into the soil.

Debbie Flower  7:15

There are many different kinds of mulches, and they vary in what they do once they're mixed into the soil. But a number one reason is that the microorganisms that break down that mulch, we're talking about organic mulch now, so it could be sawdust, it could be grass clippings, bark from trees or chippings from a whole tree, but those micro-organisms that break that down, will rush away from the plants that are actively growing and work on the mulch itself and they need some nutrition themselves to work on that mulch to break it down and release the nutrients within the mulch, and so they take the nutrition away from the existing plants.

Farmer Fred  7:58

The best mulch that, according to the Sacramento Tree Foundation you can use, is natural wood chips, also known as arborist wood chips. It's mulch that's made from all parts of a tree. When they cut a tree down, you've got all those things: you got leaves and twigs and bark and wood, and when applied in a layer four to six inches thick, the uneven size of the woodchips allows them to lock together. It forms a thick mat that blocks weeds, retain soil moisture, insulates roots from extreme temperatures. It also improves the soil over time, lessening compaction, feeding beneficial soil microbes, providing nutrition for your tree. And as long as you apply it correctly on top of the soil, and maybe even put a layer of compost beneath that mulch, that will serve as a little extra nutrient boost. But you've also talked about something that a lot of people will say, ”I did not know that”. And that is that mulch protects your garden from rainstorms, in a good way.

Debbie Flower  8:55

Yes. Rainstorms and overhead irrigation, the water coming down from above, whether it's from your spray irrigation or from raindrops, is so powerful that when it hits the soil, it can cause soil compaction, it can break down soil structure into the tiniest little particles of soil. And then they find their way between other particles. And pretty soon your soil is very, very hard and compacted. And compact soil limits the ability of oxygen and water to get to the plant roots. So it's not a good thing for the plant.

Farmer Fred  9:27

A lot of people ask me, “How do you get a tree company to drop off a load of these wood chips of some tree that they cut down?” It used to be you could go up to the truck when you heard the loud engine of the chipper/shredder. You've told the famous story of being awakened by the sound of a chipper shredder early one morning and dashing out the door.

Debbie Flower

Yes, yeah, to find that. Gotta find it and see if they'll drop it off in my yard.

Farmer Fred

Yes. I think now they've been trained to say, “Oh, just call the office. We'll put you on the list.”

Debbie Flower  9:56

Right. It's become more and more popular for people to want those chips and so that is the response I got most recently when I did that, right.

Farmer Fred  10:03

Yeah. And most companies are glad to do it. And it's nice that it's centrally controlled.  You may not get it that day. But at least you're on the list. I often worry, though, about that load of a tree that they took down. Why did they take the tree down? Was there a disease or a pest associated with it that could transfer to my garden?

Debbie Flower  10:24

That's a good question. And there could have been a pest or disease in that plant that was taken down. But all research has shown that those diseases and insect pests and fungus and bacteria, all those things, do not survive the process of the chipping and then the moving of the pile. They rely on the intact plant in order to live. Termites don't live in wood mulch. They rely on bigger pieces of wood not on this chipped up stuff that's piled up with lots of air between it. It gets wet, it dries out, it's a very different environment. So the diseases, as well as the insect pests, etc, that may have caused the demise of the tree do not survive the process, so they don't come to your house. The one thing that does have that potential, is a seed. I have had things come up in my yard from seed that came in the chipped load.

Farmer Fred  11:20

How many loads have you ever received? And was there ever liquidambar seed balls in there?

Debbie Flower  11:26

Liquidambar. Yes. My son had a load delivered and all these golden rain trees came up. Koelreuteria.  And I had a Casuarina in my yard because it came as seed in the mulch.

Farmer Fred  11:39

Casuarina is the Mountain She-Oak?

Debbie Flower

Yes. Or the river She-oak. Yeah.

Farmer Fred

What about eggs, insect eggs? Can they survive the chipping job?

Debbie Flower  11:48

They would be chipped. They will be physically beaten up.

Farmer Fred  11:51

It's not a bad mix, if you think about it. When they chop down a tree, you're gonna get leaves, you're gonna get twigs, you're gonna get the bark, the wood and everything. But all of that is basically delivered to you in different sizes. So things are going to break down quicker. So it's really a nice process for slowly feeding the soil as it breaks down. So anyway,  the chipped and shredded tree parts is the Sacramento Tree Foundation’s best idea  of a mulch product to use: natural wood chips. Okay, let’s get back to the list, the next category is down a notch from best: they talk about bark. And a lot of people when you think of chips, shredded tree parts and think well, I'll just go down to the nursery and buy some bark, or I'll go to the sand and gravel place and buy a truckload of bark. There have been warnings about using colored bark. There have been warnings about using fine bark, usually called go more common here probably in California because usually redwoods right that do that. And that has a tendency to smolder if a cigarette gets in there. Colored bark.  I don't like the look of it myself.

Debbie Flower  12:57

Yeah, it's usually the cheapest stuff. So you may not be alone. Yeah.

Farmer Fred  13:00

But that it includes chunks of the trees, outer bark, you're right. So it's all the same size. Parts of it are not going to break down sooner than others, right.

Debbie Flower  13:12

And bark is the part of the tree that contains a lot of waxes and oils. And those slow down the breakdown of that mulch. So a better place I think for the bark alone. The stuff you buy in bags or get at the local supply store is pathway bark, designed to be walked on. And there's a certain size that is pathway bark. And you don't want it to break down very fast. So that it will break down more slowly than the mix. It will break down eventually but much more slowly than the mix of the arborist chips.

Farmer Fred  13:44

Pathway bark is fairly small. It's about one inch. Pathway bark is also suggested as one of three ingredients in making a blueberry soil mix, along with peat moss and a rhododendron-azalea- camellia soil mix. And a handful of soil sulfur. Don’t forget that. All right, but that's for blueberries. They did have one suggestion though: if you're gonna go buy commercial bark…

Debbie Flower  14:14

Because you liked the look, because you like a uniform look, and it does break down more slowly than the the bark chips from the arborist…

Farmer Fred  14:21

Put down the chipped/shredded tree parts first and then top that with your commercial bark. Right?

Debbie Flower  14:26

You'll get that look. Yeah, it's so uniform.

Farmer Fred  14:29

Yes. Everybody becomes rich except you. Back to the mulch rankings. it's not rated best, it’s rated okay. And that's shredded leaves, straw, lawn clippings, and compost. Organic Materials like leaves will break down over time enriching the soil, encouraging a healthy soil microbiome, they say, and feed your tree. They are best combined with heavier organic matter like wood-chips. Only use weed free sources. I'm a big believer in shredded leaves, because they are free.

Debbie Flower  15:01

Okay, all those things were green: shredded leaves, straw, lawn clippings, compost. The biology of the soil is influenced by what the soil is fed. If you are growing trees and you feed the soil with a tree mulch that breaks down and the nutrients get into the soil, the microorganisms that proliferate in that soil are the ones that help trees. If you're growing herbaceous things, herbaceous things are green things like your vegetable garden, or your flower garden, or  your bulbs. They are green, and they benefit - while growing - more from mulches that came from green things. The biology of the soil actually changes because the things that break down the softer herbaceous green things are different. And so it becomes a fungus/bacteria balance or imbalance. So it's a predominance, it doesn't mean that the others have gone away. It's just that because of what you're feeding the soil, one predominates over the other, and one favors trees and the other favors herbaceous things,

Farmer Fred  16:10

I think the easy way to solve that issue is get yourself a chipper shredder. And let's say you have a vegetable garden, and it’s at the end of the season. Chip and shred your vegetable plants, right? And use that. Or you can put that in a compost pile and let it sit as a compost pile if you want, and then use that as a layer of mulch, even though it's compost, right.

Debbie Flower  16:35

I wouldn't even hesitate to just use it right out of the chipper shredder. It's not going to grow, you know, probably doesn't have any seeds in it. Because you're not using the fruit. Nothing is coming up.

Farmer Fred  16:46

What about tomato seeds from a stray tomato in a tomato plant.

Debbie Flower  16:49

Okay, then that could be a problem, then you would want to put it into the compost.

Farmer Fred  16:54

Yeah, exactly. process it. Yeah, compost it for a few months. And If you're worried about a load you're getting from a chipper shredder from a arborist, and they dump it in your driveway. If your neighbors don't mind, let it sit for a  month or so and it gets a really hot center.

Farmer Fred  17:13

I did that as a little experiment one time. I took my soil thermometer with a 36 inch probe and stuck it in a 10 yard, 10 cubic yard pile of chips and shredded tree parts. It was 140 degrees in the pile.

Debbie Flower  17:29

That's the temperature you want a compost pile to get to and stay at for several hours to kill the bad stuff, the seeds and that kind of thing in there. So but yes, in a composting situation, you would turn the outside into the center and and let the process occur again.

Farmer Fred  17:48

And here's something that's counterintuitive. Would you add water to increase the soil temperature, to increase the temperature of that compost pile?

Debbie Flower  17:55

Once it has dried out you need to add water. Yes, you don't want to add it so it becomes soggy. If it smells bad, or sour, then you've added too much water. And that's common. People add too much water to their compost pile. There's a compost experiment plot in Tucson, Arizona. And I don't know if it's still there, but I visited it a long time ago. And the number one thing that they know Tucson is very hot, very dry. And so you would think if you need water in a compost pile anywhere it would be there. But their results showed that the number one thing you need is to turn the compost pile it needs oxygen that the microorganisms run out of oxygen first and they die. So if you turn the pile, you add oxygen. That way a proportion of the population of microorganisms stay alive and are able to do their work, to break down the next stuff that has appeared because of your turning.

Farmer Fred  18:54

If you do want to ensure that that pile from the arborist is okay, and you have an errant teenager living in your house for punishment, tell them to turn the pile.

Debbie Flower  19:06

One year when I was working at the Skill Center and the students took care of the landscape and a vegetable garden and we had them collect all this stuff. And we had a concrete pad up against a brick building and where there were no doors or windows and we piled the compost there and then every day we went out and moved it, from one corner to the other corner of the concrete pad and the brick building every day. We had completed compost in two weeks.

Farmer Fred  19:31

There was no time for class that way.

Debbie Flower  19:34

You know, you got 15 kids out there with shovels. It doesn't take that long.

Farmer Fred  19:39

That's right. Yes. Youth and shovels. There you go. A good combination. Now also under that “okay” category is shredded leaves, straw, lawn clippings and compost. Let's talk about straw first. When you buy a bale of straw, make sure it's a bale of straw, not a bale of hay.

Debbie Flower  19:59

Hey, hay has weeds, right? Hay is the seedy stuff.

Farmer Fred  20:04

So, you want to buy straw. Straw is fine. I like to use straw for walkways especially, but it's fine as a mulch. I've got one bed covered in straw out back. And I’ll be planting onions there in the next month or so. So I'll be removing that or moving it aside and planting. Okay. Lawn Clippings scare the bejesus out of me.

Debbie Flower  20:25

Because of the pesticides used in lawn products?

Farmer Fred  20:28

Because of that, or it's Bermuda grass. Oh, yes, yes. And if you've got a turf type that grows via seeds, stolons and rhizomes, chances are you ain't ever  killing it.

Debbie Flower  20:40

Creeping red fescue is stoloniferous. And also, I believe Kentucky blue is stoloniferous. So if you're not from California, where Bermuda grass is your nemesis, there are other stoloniferous grasses that will survive or may survive because of  their stems, their rhizomes. That's the thing about Bermuda grasses. It has both stems that creep along the surface of the soil that may survive the composting process longer than the leaves do. And so you may not realize that you're putting live stems out as your mulch.

Farmer Fred  21:14

I became a homeowner in my pre Master Gardener days. And I remember listening to a gentleman talk about the benefits of using grass as mulch in your garden bed. And he never specified about the different types of grass. So I just cut my lawn and threw it on top of the raised bed. Did I ever grow a fabulous crop of Bermuda grass in that raised bed? I tell you, I bet it was forever, too.

Debbie Flower  21:40

Yeah, my dad in New Jersey would cut the grass and then put the grass, we didn't have Bermuda grass, but he would put it into a metal garbage can and he took the temperature of it with his long shanked soil thermometer too, and it got really, really hot really, really fast. Grasses can, if the layer is too thick, if grasses laid too thick, as it breaks down, it becomes sort of slimy and then it sticks to the other grasses and it can also create a cap over the surface of the soil. Another reason not to use lawn clippings.

Farmer Fred  22:11

You must be a teacher because you explained that without using the word anaerobic. But yeah, too thick of a layer of a grass mulch can cause an anaerobic situation. You want air and water to permeate to the soil. So you don't want to use lawn clippings in that regard. So if you're going to use lawn clippings, please please please don't use them in the same season that you may have used a weed and feed product. When you go and buy a lawn fertilizer these days it seems like there's more bags of weed and feed products than there is of just straight fertilizer for lawns. So you have to shop very carefully because some of these, especially the post emergent weed controls that are included in these Weed n feed products are, to use a euphemism, “persistent”, meaning they can last a long time. Despite the composting process of I've heard three years or five years .

Debbie Flower  23:04

Yeah, I I was thinking one was not enough from some things we've talked about in the past. Yeah, herbicides on lawns are some of the most destructive. Maybe it's because we use more of them as a population than we use other herbicides.

Farmer Fred  23:18

So if you're going to be planting a garden in the garden bed from seed, I would advise against using lawn clippings as a mulch if in the previous season you applied a weed n feed product,  just because of the persistence of certain post emergent herbicides which could affect it. It’s  not like a pre- emergent stopping the weeds, the plants that you planted from seed would come up, but they would be overtaken by the post emergent remnants in that base.

Debbie Flower  23:43

So they would probably grow poorly and be distorted. That  to me, that distortion, is the number one symptom of herbicide damage. And distortion means they're wrinkled or their leaves are misshapen or turning the wrong way or things like that.

Farmer Fred  23:59

If you still have that bag of weed and feed in your shed, and you were thinking of using lawn clippings as a garden mulch, read the ingredients on the bag, do an internet search of those ingredients and see what the persistence of the active ingredients in the post emergent herbicide are.

Debbie Flower

You used a lot of big words there.

Farmer Fred

I did use a lot of big words that I didn't mean to. But basically, get out the magnifying glass, read that label. And you're gonna have to be your own cop on this and look up the problems associated with each of those active ingredients for post emergent weed controls. Because post emergent means after the weed comes up, it kills a living plant.

Debbie Flower  24:40

So glyphosate - Roundup is an example of a post emergent herbicide - is not one that causes the damage you're talking about. But we only the things we apply it to are damaged by it. It doesn't prevent seeds from germinating.

Farmer Fred  24:54

The persistence of glyphosate is not as nefarious as the persistence of certain other active ingredients. Yes. If you see plants coming up that look funny, right, that should be at the top of your suspect list.

Debbie Flower  25:06

I was called in, when I worked for Cooperative Extension to a property that had, I think they were blackberries. It was spring and they were coming up from a previous season. They were perennials they had lived there previously, lost their leaves over the winter coming back. And they were all distorted. And the people wanted to know why. And it was obviously to me herbicide application that had been done in the fall. The herbicide was absorbed by the plant went to the roots, stayed over the winter. And then when the new growth occurred in spring, it was back.

Farmer Fred  25:39

Be careful. Another mulch that is gaining in popularity that the Sacramento Tree Foundation puts it in its secondary list of mulches to use. It's not in the best category, but in the “ok” category, and that's cardboard. Cardboard is very popular these days. For sheet mulching, if you want to convert a lawn to a garden, not a bad idea, and it's not the summertime, you would sheet mulch. Yes, you can look up sheet mulching. We will have a link to more information about sheet mulching in today's show notes. And sometimes it's called lasagna mulching as well, where cardboard is layered with newspaper. And that's beneath wood chips to smother the grass naturally. The cardboard eventually breaks down to enrich the soil. However, it can prevent water in the meantime, from reaching tree roots.

Debbie Flower  26:29

you're right. The people who don't like cardboard, that that's their sticking point. It is that it can prevent water from reaching the soil. Especially if it's waxed cardboard.  And they say use unwaxed cardboard, and I'm thinking, how do you know? Well, yes, and most commercial boxes if you're receiving deliveries from whatever delivery truck that drives up your driveway and  leaves a box on your porch, most of those are waxed, some are more waxed than others. If you're getting fish, or my grandfather shipped me oysters once. Boy, that box was really waxed. But others the cardboard is waxed because the delivery person might be running through the rain. And the thing inside might be damaged by water. So they wax almost all boxes.

Farmer Fred  27:12

Yeah. And the other things that do not feed soil are packing tape and staples.

Debbie Flower  27:18

Staples, I've been thinking about that tea bag thing we talked about a long time ago. I wouldn't worry too much about them in terms of soil toxicity or soil nutrition. There are metals in soil or it is rock or is what metals are made from and rock is what soil is made from. So there are metals in soil. Its toxicity is always about concentration, how much you have in one location. And I suppose I think the bigger problem with the cardboard staples are that they're huge, or they can be huge. And you can step on them and hurt yourself or cut yourself.

Farmer Fred  27:52

Yes. So try to remove as many as possible if you can. One tip that they have though, if you do want to use cardboard, is be sure to thoroughly soak the soil before applying cardboard and then soak each layer of cardboard as well. And periodically check the soil underneath to ensure that water is still reaching the roots all around the trees drip line. And where does the trees drip line go?

Debbie Flower  28:17

Well, it keeps moving out. But it is at the very edge of the branches, if not further. Yes, yeah. Yes, I did this once, this type of mulching with cardboard. And I have to say it's very difficult to wet each cardboard thoroughly. You know, you get the boxes, you break them down. You lay them down, you p