Ep. 136 - Filling New Raised Beds

Karin Velez [00:00:00]:
Welcome back, my gardening friends, to the Just Grow Something podcast. I don't know about you, but I am itching to get out into the garden and be digging in the dirt. Spring seed starting is moving right along and so is the garden planning. If you've been placing crops on your garden map these past few weeks and have found that you just don't have enough room to grow everything that you wanna grow, You might be looking at adding 1 or 2 new raised beds. We added 9 of them this past fall, and only 5 of them have actually been put together, and they're about halfway filled. Not ideal because I would prefer to have anything that I use in the raised beds get a chance to settle in and start to become a bit more biologically before I actually plant into them, but you work with what you've got. Right? If you're in the same situation I am where you've gotten behind on building your beds or you're just now deciding you need to create some, especially if you're creating a garden for the 1st time.

Karin Velez [00:00:57]:
It's important to know what to fill those beds with. Purchasing compost and potting soil can be expensive, and those beds can take a lot of soil to fill them. Plus, we've talked before that commercial compost often needs a little bit of help getting the microbes up and moving again In order to make it biologically active and not just an inert material, that's not helping our plants out at all. So Filling a raised bed with nothing but trucked in compost and bags of potting mix really just isn't the way to go. Today, we'll talk about different techniques we can use to fill those raised beds properly so that the growing medium is not only biologically fully active, which is helping the plants get the nutrients they need, but also doesn't break the bank. Let's dig in.

Karin Velez [00:02:29]:
If you're new to the podcast and haven't listened to any of the episodes on composting and are confused about why I say commercial Compost needs to sit and isn't biologically active. I will link to 3 really good episodes all about compost in the show notes. But in short, in order to kill off weed seeds and pesticide residue and persistent plant diseases, commercial compost is heated to A temperature of between 131 Fahrenheit and 170 Fahrenheit for a period of 3 days. This is between 55 and 77 Celsius. The problem is anything over a 149 Fahrenheit or 65 Celsius will cause the beneficial microbes to also die off. Most commercial compost facilities regularly keep their compost at a 160 Fahrenheit, which is obviously much higher than that. Not only does this speed up the composting process, but it's much more effective at killing off those aforementioned weed seeds and plant diseases While making any pesticide residue unlikely to affect plants down the road. So while this makes for a safe product to use in our gardens, It's not necessarily a bioactive one right away when we receive it. The nutrient content of that compost may be very good, But without the beneficial microbes to move those nutrients to the plant roots, our little seedlings are just gonna sit there trying to Stretch their roots out to pick up whatever nutrients they can come in contact with, and they will absolutely be stunted. I have seen this happen over and over again and have experienced it myself. So if you are filling a raised bed for the 1st time, the temptation may be to have a bunch of Compost delivered and dumped right into that bed to fill it.

Karin Velez [00:04:13]:
And that's not a bad approach if you have the funds to do it, number 1, And you can do this in the fall. Add some biologically active compounds like, worm castings or some homemade compost, and then be sure that the bed is open to the soil below so that any microbes can start moving their way through the soil. By the time you get ready to plant in the spring, then you will likely have a nice bed to work with. But if you're creating your beds right before you intend to plant or you can't afford to fill your beds with nothing but compost and topsoil, Let's talk about what you can do to take up space in the bed in a way that benefits both us as the gardener and the plants we want to grow. Now if you have a bed that's about 18 inches deep or so, this is gonna be a little bit easier than if you're working with one of those really tall beds that are around 36 inches deep, but the concept is still the same. It just means that you'll need them to add more of those base materials for those deeper beds. No matter what size bed you have, you're gonna start with a base layer of whatever carbon sources you have available. K.

Karin Velez [00:05:15]:
We're talking things like sticks and twigs, large rotting logs if you're filling a very deep bed, cardboard, Shredded newspaper and the other non slick paper products, shredded leaves, straw, chopped up dried corn husks and stalks, even the dried corn cobs. You can use dead, dried plants from last year's garden too so long as they didn't have any, like, plant diseases or bug infestations. You don't want those in the bed. You can even use early weeds that have popped up and don't have their seed heads yet. These things can all form the base layer of our garden Beds, they are dry, they're fibrous, and most importantly, they take up space. And as they break down in the bottom of our bed, They provide the structure for the humus that will eventually develop. This is very similar to the role that they play in a compost pile. So just about any material you would put in the compost pile can go in the bottom of your raised bed as you fill it.

Karin Velez [00:06:15]:
These materials are not only saving us some money in terms of filling the bed, they're providing air space for the Other components to break down and room for the microbes to move around and do their work. The chunky components will also help with drainage. Now keep in mind, if the soil under the bed is healthy, you want the bottom of the bed open to provide a way for the microbes that already exist in the soil beneath plus any earthworms, to just go ahead and move on up. I will usually start with a good layer of cardboard in the bottom of the bed because It helps to choke out any perennial weed seeds at the bottom, and at the same time, it breaks down quickly enough for those good guys to get through. This applies even if your soil is absolute junk underneath there. Okay? The the raised beds that I have out in the front part of my house are sitting on top of Well, that is really not soil. It's kind of a combination of, I don't know, fill dirt and solid clay, but there are still good Microbes and microbiota in there that I want to move up into the soil in those beds and start to inoculate them. But if you want to be sure you're preventing perennial weeds from coming through or if you live someplace where Soil contamination is a concern, whether that's from lead or other metalloids or chemicals of any kind.

Karin Velez [00:07:33]:
You can start with a heavy duty landscape fabric across the bottom of the bed. The landscape fabric is water permeable, so it's gonna let the water out, But it will help block your soil from coming in contact with any of the contaminants that are down below. And if you're placing a garden planter on, like, a solid Surface on a patio or some other concrete material, you can also line it with the landscape fabric. And then just be Sure to have drain holes around the bottom edges of the planter so excess water can move away. You don't want your raised bed to turn into a bathtub or drown your plants. No matter where you're putting these beds, you want this 1st chunky layer to take up all but the top Six inches or 15 centimeters of the bed. It might seem a little high at first, and that's okay. It's going to compress as you add components on top, and it will compress even more as it begins to break down.

Karin Velez [00:08:29]:
At this stage, if you have any aged Animal manure available to you. Add that in as well. Well composted manure would be best, so you don't have the chance of heating the bed up too much or Adding any unwanted microbes into the mix, but any herbivore or manure that's been aged for at least 4 months would be fine too. If you plan to plant right away into this bed, I would recommend sticking with things like rabbit, goat, alpaca, or sheep manure. It's got a bit less nitrogen content than, say, the chicken, the horse, or the cattle manure, unless, again, it is really well composted. I do not recommend fresh manure of any kind other than rabbit manure, and that will be our topic of discussion on this week's focal point Friday episode, so stay tuned for that. I am experimenting this year, though, with burning our chicken manure and using it as a biochar of some sort, in the bottom of 2 of the new raised beds and then doing a side by side comparison. The manure is coming out of the chicken coop, and it's combined with bedding in the form of straw and shredded pine, So it should burn nicely.

Karin Velez [00:09:37]:
This is not only gonna give me the benefits of the char in terms of nutrient and water holding capacity, But burning the manure ahead of using it is killing off the possibility of any unwanted microbes, you know, like E. Coli or Salmonella, and lets me use it without having to compost it for 6 months to a year. So we'll see how it goes. I will absolutely report back and let you know how that works. Now if you don't have any manure to add at this at this stage, that's okay. We're gonna move forward with the soil components. And this is where a lot of gardeners will get tripped up. What you put in this layer is going to be what your plants this Season mainly rely on for their growing medium and their nutrition. So let's be very clear about what we do and do not want to use.

Karin Velez [00:11:33]:
The thing we want to steer clear of when adding the soil component to our raised planters is straight garden soil or black soil or top Soil that you buy in bags at the garden center or have brought in by truck. If you break one of those bags open, you can very clearly see the structure of this Soil is very dense. These soils are intended to be used as an additive to in ground beds to improve their structure or as just 1 component in the creation of our raised beds. They should not be used all by themselves. But if you use topsoil in combination with compost, then we're getting closer to creating that loose well draining soil that's full of nutrients, which is exactly what we want. If you can find pulverized topsoil, which just means that it's been ground down so the texture is very fine and not chunky, That would be perfect, but anything labeled topsoil should be just fine.

Karin Velez [00:12:29]:
If you mix the soil and the compost in about equal parts, Now we're getting closer to that texture and that nutrient content that we want. Now if you have decent topsoil from your own property that you can use, that's Fine too. Just be sure that you've tarped it off beforehand to kill any weed seeds. In fact, that topsoil is great because it's Going to contain some of those native microbes that are essential for getting the nutrients to the plants. So if you have an area that you'd like need to level off anyway, then go For it, use that. Just make sure that you include the compost component with it. Speaking of compost, if you have compost you've been making at home, but it just isn't quite finished yet. Go ahead and use that as part of that lower layer of bulk.

Karin Velez [00:13:13]:
So long as you're pulling out any really big pieces that might get in the way or attract Pests, it's totally fine to use. It's not gonna heat the bed up so much that it would be detrimental to the plants, and it is going to take up some of that space. Just keep the unfinished stuff in the lower portion of the bed. If you have finished compost from your own pile, you wanna be using that in those top 6 inches of the bed. If you don't have your own compost or yours just isn't far enough along to use right away in a bed, then purchased compost is going to be your best option. You can either have it trucked in if you're buying a large amount or you can purchase individual bags of compost off the shelf at the garden center or the nursery. Now if you have other gardeners in your friend group or you belong to a local gardening group on Facebook, I would totally recommend asking for their opinions on the compost that they have personally used in the past. Some operations are definitely better than others when it comes to the trucked in compost, and the bagged Stuff can be hit or miss if you aren't familiar with the brand.

Karin Velez [00:14:14]:
So definitely get some recommendations if you can. Remember, this soil layer we're talking about Should be about the top 6 inches of your container. I generally will use the compost and whatever soil I have available, And then I add good potting soil to that top layer, especially if I plan to plant into these beds right away. Again, we want a good texture and a good nutrient content. The reason I use potting soil as one of the components is because It has that great texture. It also contains vermiculite or perlite that's going to aid in the structure and the water retention. And it also has some nutrients to it that will be immediately available to my plants while I'm waiting for that compost to become more active. I love my pro mix for this.

Karin Velez [00:15:01]:
I use it for everything, and that includes my raised beds. I get really great results this way, and I generally make sure that about 20% of that 6 inch layer is comprised of potting soil. Now if you would rather just stick with compost and topsoil, that's fine too. The potting soil is just my preference for jump starting a bed that I'm going to be using right away. And speaking of jump starts, Another component that I add to this top layer is worm castings. The folks over at Elm Dirt sell their worm castings, and I can tell you I've seen such a difference Since I started using the castings in my beds, I talked about starting my own vermicomposting bin for this very reason, but, you know, I haven't gotten started on The components are still sitting around, waiting for me to get off my butt and do it. But in the meantime, I'll have to stick with buying them for now. If you can't get castings, use an amendment that has something in the way of biological activity, like using, Elm Dirt's plant juice.

Karin Velez [00:15:58]:
I've used that too. Or you can choose some compost tea or anything that you can find that is labeled with microorganisms. It's all about making that soil come to life. Do you need these things if you're putting these beds together in the fall And not planting until the spring, not necessarily. That soil is going to have plenty of time to become inoculated with the microbes all on its own. These things will boost that effect, but the compost and the topsoil should do fine on their own at that point. But if you plan to plant into the beds right away, I highly recommend the potting mix and some sort of biological component. Your plants will thank you.

Karin Velez [00:16:40]:
So Focus on the best of the best going into those top 6 inches because that's where your plant roots are going to be drawing their nutrients from. Once those other components down on the bottom start breaking down, they'll be adding their own nutrients and structure to the soil in the bed, And you'll notice that soil levels start to drop over time. This is normal. Those as those components decompose, you're gonna see that it's gonna drop. So you'll need to be prepared to be adding additional compost to the top of the bed from time to time. Just be sure you're adding the new layer of compost that you mix it in with the existing soil in your bed so it can be inoculated with those good microbes, and they can go to work right away for your plants. Cover crops also work well for adding biomass and nutrients back into your raised beds as that soil level starts to drop. You can also just do what I do and use the compost as a mulch during the growing season, and then leave it there in the winter to naturally break down and work its way into the soil.

Karin Velez [00:17:40]:
Then in the spring, plant directly into it and then add a new layer of compost as your new mulch. I hope this episode was helpful. Remember, fill in the bottom of those beds with chunky natural materials that will fill the space, But also break down over time, concentrate on the high quality stuff in the top 6 inches of the bed, and be prepared to add new layers of compost as time moves on to keep the bed healthy and happy. If you found This episode helpful, I would love it if you would share it with a gardening friend. You can find all the episodes in one spot where it's very, very easy to share over at just grow something podcast.com. I will see you back here again on Friday for that focal point Friday episode about using manure in your garden beds. Until then, Keep on cultivating that dream garden, and we'll talk again soon.