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.
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!
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.
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?
This week has seen the completion of two major parts of our renovation process: the permeable pavers in the classroom area and the raised beds! From here we have lots of smaller projects to put the finishing touches on the garden and one big project – filling the beds with soil.
The guys doing the drainage work (I showed you the holes last week) go those all finished. After the rain on Monday night, the only place we had any water standing in the garden was in the lattice garden area right be the sidewalk. Oh well…it was too much to hope for that everything would be perfect!
Last Friday was rather overcast, so it was a good opportunity to take some pictures of the classroom area without all the fun shadows. They had all the pavers laid except for the ones that needed cutting to fit around the edges.
Our crew also started constructing the plastic lumber raised bed. You can see that we’ve run out of extra soil and gravel to level things out on this end, so we’ll have to wait until we start filling the beds to get that part finalized.
This is a look at the finished plastic lumber bed. We used Azek decking, which is pretty expensive. This was the most expensive bed, but it should last for a long time! You can kind of see the two-tiered look, which maybe isn’t as dramatic as I hoped it would be, but I wasn’t about to buy more of this lumber. I think it will stand out more once the osoil is in and we have everything perfectly leveled.
Here’s a look at the finished garden, minus the soil, drip lines, and mulch. The construction is done! We’ve come a long way! If only there wasn’t 40 cu. yards of soil to move yet…not to mention all the paths to mulch…
We are making progress! With any luck, we should have the last 2 raised beds built and everything ready for soil by next Tuesday. Last Friday we built a raised bed out of landscape timbers and placed two beds made of red cedar. One of the Master Gardeners had pre-built them in his garage.
This week, the Master Gardeners came back and built the treated lumber raised bed. That means all we have left is the grape bed and the recycled plastic lumber/decking lumber raised bed to complete.
Today, the drainage & irrigation contractor is back to finish their part of the job, which includes digging drainage holes at regular spaces in the beds and filling them with gravel, then covering them with filter fabric. They will also get the ball valves for our drip lines installed.
The landscape timber bed was a little bit of a challenge, because the timbers are cheap, and can sometimes be a little bit warped. So we had that to deal with, in addition to the usual project of keeping the beds level.
Here you can see the finished treated lumber bed. It is a little hard to see, but we decided to make the end of the bed angled to follow the pavers rather than straight. I’m still not sure quite what I think of that, but I’m sure it will be fine. Each of those yellow flags is going to be one of the drainage holes in the bottom of the beds.
Here you can see the two drainage holes dug in one of the smaller, red cedar beds. Just to be clear…this is not something that the average person would have to do when building a raised bed. We are putting the additional drainage in the bottom of the beds because we are on a compacted clay construction pad. The drain holes are supposed to be dug through to the sandier, natural soil underneath the compacted clay, just to make sure we’ve got sufficient drainage. With all this drainage, I hope we’ll be able to keep the beds well watered!
I’ll show a few more pictures of the finished drains tomorrow or Monday.