Tag Archives: seedling flats

Starting green bean seeds

We are late in getting these seeds started, but today we got enough seeds in grow boxes that we can do one full 30 foot grow bed in bush beans.  There are 9 rows in this seedling flat with 15 seeds in each row.

Notice the old vegetable can with sand and a white handled spoon sticking out of it?  IRS my preferred method to cover those seeds with wet sand.  It cover the seeds and the use the back of the spoon to even out the sand with the growing medium.  The sand, when wet, just doesn’t shake out of the can easily.  

After the picture was taken the rest of the seeds were covered and the seedling flat was covered with burlap.  We water the seeds daily through the burlap seeds sprout.  The burlap diffuses the water and helps prevent the seeds from being washout out of the sand.

Want to build your own seedling flats?  See this blog entry.

starting bean seeds in a Mittleider seedling flat

Building a few more seedling flats for seedling production 

Today the table saw came out and we quickly constructed a few more seedling flats.  It’s time to bump up a few of the vegetables under out grow lights, starting with the kale. They’re pretty simple to make and relatively inexpensive.  

The flats are 18″ X 18″. The instructions for building your own can be found on page 181 of the MGM book. We used the table saw to cut the two widths of the slats for the bottom of the seedling tray and a pneumatic staple gun to assemble each part. 

4 completed Mittleider seedlijng flats
completed seedling flat
conatucting a Mittleider seedling tray
Mittleider seedling flat

seedling flat growing medium

Seedling flat growing medium

Every year when I start getting ready to grow seedlings I mix up a batch of seedling flat growing medium. By starting with new growing medium every year I ensure there are no insects, plant disease or weed seeds.  This helps to ensure healthier plants are going into my garden and I am not introducing weed seeds to the garden.

How to mix custom soil

Time to mix up the sawdust, sand and perlite that will be used as our growing medium in our seedling flats.   We mixed 2 parts sawdust, 1 parts sand and 1/2 part perlite for our seedling flat, as seen in the pictures below.  The perlite is optional and can be omitted to keep your costs down.

We mix everything in a wheel barrow with a flat nosed shovel before transferring everything into our seedling trays.

The Mittleider Gardening Course book recommends 3 parts sawdust to 1 part sand.  It also gives options to sand and sawdust, including mixing ratios.  Get your own MGC book here if you don’t already have one.

growing medium being mixed in wheel barrow
growing medium being mixed in wheel barrow

Seedling flats are shown in the Mittleider Gardening Course book on page 181.  The dimensions of the seedling flats are 18″ x 18″ x 2 1/2″.   Once filled with the mixed growing medium we added 1 1/2 ounces of our pre plant fertilizer mix. (Page 51 in the MGM, revision 4)

After mixing our growing medium it will be added to this Mittleider seedling tray
After mixing our growing medium it will be added to this Mittleider seedling tray

Do you prefer to use your own soil?

Not everyone wants to mess with the extra work of acquiring everything to make a custom growing medium.  The correct sawdust can be difficult to find and even expensive when you do find it.  You can sterilize your own soil and grow healthy seedlings.  See my blog post on Seedling Success Through Sterilized Soil.