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Video Wednesday
Since we have been talking so much about soil in our new raised bed, I thought I’d share this video from one of our Horticulture Agents about adding organic matter to clay soils. He’s discussing it in the context of flowers and ornamentals, but the information is good for food gardeners too.
A Couple of Garden Problems
Looking over the garden this morning after the weekend, I spotted a couple of things going on that will result in replacing a couple of plants around the garden.
This is the first problem I noticed. I saw it when the damage was fresh Saturday morning as well. While it is theoretically possible that there was a weak spot on the stem that the wind snapped, I think that the most likely culprit in this case is a cutworm. Cutworms like to wrap around the stems of young seedlings or transplants and chew them off. That is exactly what this looks like. This pepper plant is done for, at this point. We will be replanting this one tomorrow.
This tomato plant is the worst, although I can see 3 or 4 others with similar symptoms. At first glance, most people would say that the plant is wilting and needs a drink of water. Very tempting response! However, there were three things that made me question that immediate reaction. First, while the plant is wilted, there is no sign of leaf scorch or similar damage that there should have been after the warm weekend. Second, I felt the soil a couple of inches down and in felt moist. If the plant can’t get water out of that soil, then it has some type of root damage, but isn’t yet to the point of scorching. Also, the lower leaves were looking rather yellow, which to me says that the plant has either been getting too much water or it is suffering from too few or too many nutrients.
What I am wondering is if in our concern for keeping the soil moist enough for our germinating seeds, we actually OVER-watered the tomatoes last week. As tempting as it is to put more water on a wilty plant, I’m going to try to hold off the watering and see if they will perk up again. If not, we’ve got some plants in reserve to replace the couple sickly looking plants.
It is theoretically possible that these plants were planted in a localized hot spot due to the compost that we used. I haven’t gotten all the results back yet, but I expect some high numbers. Or…maybe the nitrogen has all been leached out…that also causes yellowing. (But not wilting.) Hmm…
Garden Renovation: Almost the End
It is hard to believe, but then end is in sight on our garden renovation. Really, we could plant now if we weren’t picky. But we are picky, and this is Kansas, so we WILL have the drip system installed before planting!
Since my last update we have completely filled all of our raised beds with our soil mix and have all the paths mulched. It feels great to be so close to having a complete garden again!
Let’s talk about our raised bed soil mix, and why I don’t recommend that you do what we did. This is definitely a case of “do what we say, not what we do.”
We mixed sand and compost at about a ratio of 3 parts compost to 2 parts sand. Normally, I would not recommend that you use pure sand in a raised bed, for several reasons.
- First and foremost, a raised bed is supposed to be a method of improving your existing soil, not ignoring your native soil and using something else. I always recommend using your existing soil and adding additional topsoil and compost to fill a raised bed. In this area, most of our soils are clay loams. If you add some sand to a clay loam, you make very nice adobe brick, but not very nice garden soil. (In our case, we weren’t planning to garden in the existing soil as much as garden ON it, so that wasn’t a consideration.)
- Raised beds facilitate drainage and cause soil to dry out quickly. Sand drains and dries out quickly without a raised bed, so it could be a challenge to keep it watered.
- Sand is very poor at holding nutrients. We’ve balanced that with the amount of compost, but it could be several years of adding compost before our raised bed mix is a nice loam instead of a compost & sand mix.
- Sand in this area of Kansas usually comes out of sandpits, and sandpits often have very salty water in the bottom. Topsoil can also have its own problems, so maybe this is a case of “6 of one, half dozen of another.” No matter what, you should always get a soil test done before planting in a new soil mix!
In our case, we are “creating” new soil from scratch without much intention to use the existing soil at all. That makes the sand not a problem. Also, once we got down to the native soil beneath the clay hard-pack, it is a sandier soil. If you are starting from a clay loam native soil, you probably shouldn’t use sand.
Okay, back to filling the raised beds.
Here’s a big pile of sand.
And a big pile of composted horse manure. Obviously not mixed with the sand yet. The sand arrived first, so we started filling beds with a layer of sand, thinking it would be easier to mix the sand and compost in the beds than in the wheelbarrows.
You can see that we put about 3″ of sand in the bottom of all the beds, and then started mixing compost once it arrived. We also put some of the sand down in the walkways in areas where the gravel was a little thin and also under the edges of the raised beds in spots where we didn’t have enough gravel/soil to get the edges leveled right.
We also took some time to dig down and place some rebar stakes next to the water lines to stabilize them. Since they are now tied in directly to the irrigation main line, the water pressure is crazy high, and we wanted something to hold that plastic more stable.
After the first go-round with the sand and compost, we figured out pretty quickly that it was much easier to do alternating scoops of sand and compost into the wheelbarrows rather than mix in the beds. Much better!
The semi-mixed soil was much easier to work with in the beds!
Here’s the end result. About 20-25 Master Gardener volunteers worked Monday and Tuesday mornings and Wednesday afternoon to get to this point – beautifully filled raised beds and completely mulched pathways!
As we were getting our sand and compost deliveries, I pulled soil samples of the sand and compost individually and also a bag of mixed sand and compost to get tested. We are testing for pH, N, P, K, Organic Matter, and salt-alkali. The salt-alkali is a test that measures the amount of sodium as a percentage of total soluble salts. Because of the sand, I wanted to make sure everything is in good shape before we get too far along. When we get the results back, I’ll be sure to fill you in on what we find!
Our remaining garden renovation tasks include:
- Installing the drip irrigation lines
- Construction of the handicap accessible raised bed (details TBD…this may not be very soon)
- Installing permanent signage (developed over the course of the year)
- Installing signage for each bed in some form
Of course, we will also quickly be moving into our regular pattern of gardening (and blogging) as we hopefully can get some planting done in the next couple of weeks.
Raised Bed Soil Mix
We have one raised bed with soil in it! Granted, it is one of the small, square beds, but it’s a start! We’ll be filling the rest of the raised beds throughout the week.
This particular raised bed we got a donation from Gard’n'Wise to try one of their specially packaged raised bed soil mixes. We certainly don’t recommend that you HAVE to use a mix like this (we aren’t for the rest of them!). It will be fun to try it and see how it works though.
We put about 5 inches of woodchips in the bottom of the raised bed, because we didn’t have quite enough of the bagged soil mix to fill it completely full. They will break down over time and we can add more compost to the top to make up the difference.
Here you can see the list of ingredients in the mix. I don’t know how it holds water, so I’m not sure I agree with the bag’s recommendation as ideal for container gardening. Maybe it would work well for some of those big, Smart Pots that we tried a couple years ago. It is a mixture of topsoil, cotton burr compost, coconut coir, expanded shale (kind of like gravel, but popped like popcorn), humate, and several different types of ground rock/sand. I’ll be curious to see how it tests when we run the soil tests on it.
It actually looks kind of disgusting, if you think about it too much. The long fibers are most likely the coconut coir. You can also see a couple of the expanded shale rocks on the left side. Otherwise, just a nice, light (relatively) mix of soil. Definitely not as light as a normal soilless potting mix, but lighter than your average, mineral garden soil. I wonder if we will have trouble keeping it moist in a hot year?
There you have it! Our first filled raised bed. Now we are guaranteed at least one 16 sq. ft. area in which to garden this year.
Why Good Drainage is Important for Your Garden
This is just one of the reasons that we are renovating our demonstration garden:
The tracks are from several weeks ago, when we were working to remove the remaining concrete from the wheelchair garden area. There had been a little bit of rain a few days before, and the bobcat left these ruts. Ugh. Since then, they haven’t drained. Granted, a lot of this water is from yesterday and today. Still…it isn’t even pretending to drain. It’s just sitting there.
The first part of our garden renovation is going to be putting in drain tiles that will help move water away from the garden, especially through our lovely, sticky clay, compacted construction pad. When our building was originally built, this area was compacted like the foundation area. Then a little topsoil was added and proclaimed “ready to garden.” Yeah, not so much. These conditions are why we have always used raised beds and worked hard to develop a high organic matter loam soil in those beds. Even with the added drainage, these conditions are also why we will always use raised beds in our Demonstration Garden and also why we recommend that almost all home gardeners in this area also use raised beds.
Many parts of Sedgwick County naturally have a very heavy clay soil like is below our demonstration garden. If you can dig a hole in your garden or yard and fill it with water, and it takes more than 24 hours to drain, you absolutely need either a different location or a raised bed or berm to make your garden successful.
Why does it matter? Isn’t it just water that the plants can use? Actually, it matters a lot. Plant roots need oxygen as much as we do, and if the soil is full of water, there is no space for air! Water can smother the roots of the plants and increase the ability of some problematic diseases to move around in the soil and infect plants.
It might seem ironic to be talking about drainage as a problem after such a dry year. But if your soil is compacted and poorly drained, even a dry summer doesn’t protect you from problems. If anything, it makes it worse because your soil is either soggy or rock hard.
Improving soil drainage and structure. The reason we recommend raised beds so often is that they are a relatively quick solution to a problem that might otherwise take many years to fix. The way to actually improve your soil as it is will vary with the exact problems, but it would include a combination of deep tine aeration/ripping, incorporating organic matter by the ton, and probably planting some deep rooted cover crops like winter radishes that can break up the soil over several years (and incorporating them for more organic matter). Even then, you will still have a heavy, clay soil, albeit with better organic matter and drainage. Given all that work, raised beds seem like a good choice, don’t they?
