If you just can’t find good sawdust locally you can pick up these equine pellets made from pine at farm supply stores. I understand that pellets for the pellet burning stoves can also be used and found cheaper on sale and in bulk.
We use sawdust in our Mittleider garden for our grow boxes and in our seedling trays. Each year we top off the grow boxes before the growing season begins. Today we made the trip over to a nearby town where a sawmill allows us to shovel our own sawdust for free. They make pallets and are largely cutting inexpensive cottonwood trees for the lumber. Any tree expect the black walnut provides a usable sawdust for a Mittleider grow box or seedling tray
The sawdust is mixed with sand for both the grow boxes and the seedling trays. For the grow boxes it is mixed at 3 parts sawdust and 1 part sand. For the seedling trays it is 2 parts sawdust to one of the sand. Both are mixed by volume. I’ll try and take some pictures that show the size of the particles. Too large and too fine are both bad.
No idea how much wood they cut in a week, but this sawdust pile is massive, the picture truly doesn’t do it justice.
After receiving a good hard frost we decided to dig up our Georgia Jet sweet potatoes. We are tickled with our harvest that ended up filling a wheel barrow. Not sure what the total weight as we just didn’t weigh them.
They were growing in a 4 foot wide and 15 foot long grow box that was filled with a mixture of sand and sawdust. Digging them was very easy, we used only our hands to sweep the sand and sawdust out of the way to expose the sweet potatoes.
You can see the outline of the growbox in the picture below. As you can see, they grew like mad. Next year I will prune the vines as they grow beyond the box.
This was the average size of what we harvested. They grew easily in our sand and sawdust and weren’t mishappen.
This is the completed harvest here in the wheel barrow. Not a bad haul for a 4 x 15 foot growing area!
We now have 32 Georgia Jets sweet potato slips in our 4′ X 15′ grow box. I’ve never knowingly eaten one before but wanted to give them a try. This is also our first year growing any sweet potato in a grow box with a sand and sawdust growing medium. Last year digging potatoes in the heavy clay soil was a lot like work. This year it should be so easy.
I’m still working on clearing the grass and weeds around the grow box. When finished there will be a bare dirt border 5 feet from the box. By doing this it helps keep insects away from our vegetables. It also helps keep weeds from getting into the grow box and competitimg with the vegetables for the water and fertilizers as well as space and light.
With the grow boxes filled with medium and seedlings transplanted our next project was the completion of the automated watering system. Lesson 16 in the MGC book, page 125, covers the construction details of the automated watering system. Three holes were drilled every 4 inches of the 3/4 inch schedule 30 pvc pipe to water our grow box. The holes are small, we ordered the number 57 drill bit from Amazon as our local stores don’t carry anything so small.
The holes are positioned to get a stream of water to squirt straight down into the bed and the other two at an angle towards the outside of the box. Our system will be drained in the winter as it turns cold. For all the piping that is below ground we elected to go with schedule 40 to help ensure we don’t have to dig up a broken pipe.
Currently we water by connecting a garden hose to the system. At some point we may go high tech and use a truly automated system.
These 30 foot long and 18 inch wide boxes are being built for our fall crops. We will also be building an in garden green house over these boxes. This will allow us to extend our growing season by 12 weeks.
Once construction is complete they will be filled with a mix of sand and sawdust as our growing medium. As that growing medium contains no nutrients for the plants we will be providing all of the necessary nutrients via an inexpensive mix that is applied on a weekly basis.
The PVC you see next to the treated 2×8 serve a few purposes. They help hold the boxes level and in place once filled with our sawdust and sand growing medium. They also support the a-frames we will be making by heating and bending some half inch pvc. Once the mini a-frames are in place they can then be covered with green house plastic to protect our fall crops.
Next to the grow boxes you can see our sweet potatoes growing like mad.