How We Built Our High Tunnel Greenhouse

My wife and I (with help from a lot of friends) just built a high tunnel greenhouse at Bear Butte Gardens.  And, I’ve got to say, it’s a lot bigger job than I expected.  But we learned a lot, and it should be pretty amazing once it goes into production!  In this article, I thought I would share some of what we learned about this project.

So, what is a “high tunnel”?  According to the internet:

A high tunnel is a tall commercial or industrial-sized greenhouse. These are used in commercial agriculture applications to maintain a more reliable and uniform temperature and humidity and to protect plants from variables such as wind.

Depending upon who you ask, the definition of a high tunnel usually includes the characteristics of a hoop-style structure, covered with clear plastic, in which the long sides can be opened (rolled-up) to allow additional air ventilation.

Our High Tunnel Greenhouse, nearly finished

We purchased our high-tunnel as a kit from a company called FarmTek (www.FarmTek.com).  The model we have is the “Premium Round Style High Tunnel”.  Ours is 30 feet wide, 72 feet long, and 12 feet tall.  The price listed on their website for this kit is about $6,000.  The good folks at our local Natural Resources Conservation Service (NRCS) office in Sturgis helped us with partial funding for the kit via the Environmental Quality Incentives Program (EQIP) grant.  If you are interested in this program, then you should visit the NRCS office and/or visit the NRCS website (www.nrcs.usda.gov).

In addition to the basic kit, we purchased optional rafter support kits and a shade cover from FarmTek.

If you are familiar with where Bear Butte Gardens is located, then you know that we get harsh weather -- mainly the wind.  We are located on the top of a rolling hill on the prairie near Bear Butte.  In the past, we’ve had wind micro-bursts that have blown our garage door in (collapsed it), blown the front door off our house, blown siding off our house, broken window frames, blown shingles off our roof, as well as several other mishaps.  So, when I say windy, I mean it.  Due to these extreme conditions, we have chosen to enhance (strengthen) our kit even a bit more.  I’ll try to identify these enhancements as we go along.

The basic kit consists of galvanized steel hoops (rafters) that make the frame of the structure.  The rafters are located four feet apart.  Our kit has 18 rafters (4 x 18 = 72 feet).  Each rafter is composed of five sections of curved conduit pipe, secured with “Tek” screws.  The rafters are mounted to ground posts.  The ground posts are straight pieces of galvanized steel conduit pipe that are three feet long.  The ground posts are driven vertically into the ground or secured in concrete.  The rafters are connected together by straight pieces of galvanized steel conduit pipe (purlins).  The straight conduit pipe comes in lengths of about six feet, with one swagged (male) end and one non-swagged (female) end.  Twelve sections of straight conduit pipe are connected together (with Tek screws) to form one entire purlin that is 72 feet long.  The purlins are connected to the underside of rafters on the top of the structure.  Our kit has five purlins that run the entire length of the structure.  The intersections of rafters and purlins are secured with special clamps, bolts, and screws.  One large piece of clear plastic is stretched over the structure and secured with a series of “u” channels and “wiggle wires”.  The two end walls each get their own piece of plastic covering.  The plastic on the long sides of the structure can roll up to a height of about four feet to allow additional ventilation.

The kit, unpacked

This was the first high tunnel kit that we have ever constructed, so the learning curve was interesting to say the least.  The instructions that come with the kit (or maybe my ability to comprehend the instructions) leave a lot of room for improvement.  Anyhow, I’ll try to give you an idea of how we did it, and also share some of our discoveries, tips, and tricks -- just in case you want to build one of your own!

Step 1 - Planning
What are your objectives?  Do you want to extend the growing season?  Are you growing for family & friends or for commercial purposes?  Do your homework.  Search the internet.  Watch YouTube videos about high tunnels.  Visit someone who has a high tunnel.  Ask questions.  Contact the NRCS.  If you are seeking financial assistance from the NRCS, then get familiar with their requirements.  Select a building site.  Think through how you will actually grow and harvest the plants -- things like sunlight exposure, pollination, watering and drainage, temperature control, soil nutrition, planting schedule, harvesting schedule, pest control, disease control, etc.  What size/shape structure is right for you?  How about access to/from the structure?  Compare various manufacturers’ products.  Plan for transportation (our 2,000 pound kit was shipped by truck to Box Elder and we hauled it from there to Sturgis).  Know the warranty info.  Plan for additional/optional building materials.  Plan for the actual labor and time of constructing the kit.

Cedar posts and composite lumber

Step 2 - Prepare The Building Site
We have a friend with a skid-steer loader who leveled our building site.  Before he did his work, I removed the topsoil with my tractor.  We used a transit to get the site flat and level.  I think we did a fairly good job with this step, but next time, I will work at getting the site even more precisely flat and level.  We then placed the stakes, put up string lines, did our measuring, ensured the squareness, etc.  It is very important to get things straight, level, and square.  We marked where each and every ground post would be installed.  Our kit has 18 ground posts on each side for a total of 36.  The tasks of pacing the stakes and string lines took several hours.  Someone with more experience would probably be able to do it faster.

Dirt work

Michelle, using the transit to help get the ground flat and level

Step 3 - Install the Ground Posts
I happen to have a tractor with a post-hole digger, so we used that to drill holes in the ground, one for each ground post.  We mixed one bag of redi-mix concrete per hole and then placed the ground posts vertically in the concrete.  In the previous step we installed string lines so that we could get the ground posts set in a straight line, and all to the same exact height.  If you have access to a transit, then use it for even more exact height measurement.  This was two summer evenings (after my day job) till dark plus drying time for the concrete.

The tractor and post-hole digger made the job easier

A corner ground post, with string line

Step 4 - Install Rafters and At Least One Purlin
This is a job that requires several people.  First assemble the rafters on the ground.  Then raise the first rafter and attach it to the first pair of ground posts with bolts.  Use ropes to pull the rafter into vertical position, and then temporarily stake down the ropes to hold the rafter in place.  Then raise the second rafter and attach a purlin between the two rafters.  Simply repeat this process for all remaining rafters, working your way from one end to the other end of the structure.  We are lucky enough to have another friend who let us use his scaffolding, which made the job much easier, safer, and quicker.  I also made a jig to measure the distance between the rafters (exactly four feet).  This jig was made from a scrap piece of 2x4 with two notches cut in, four feet apart.  This was one fairly long day with several people helping.

Assembling the rafters on the ground

Putting up the 1st three rafters and one purlin



Using the 2x4 Jig to consistantly measure distance between rafters



Step 5 - Install Additional Purlins
After we had all 18 of the rafters in place, we installed the additional four purlins.  This takes a considerable amount of time because each intersection of a rafter and purlin has a clamp with two bolts.  After the clamp is installed then a couple of Tek screws need to be installed into the conduit piping.  This is a considerable job when working on a ladder or scaffolding.  18 rafters x five purlins = 90 intersections.  This consumed several summer evenings.

Installing additional purlins

Step 6 - Install Footer Boards
We chose to install the optional footer boards.  We used composite (plastic) boards (we are USDA organic certified so we can not use treated wood) about 1¼” thick, about 5” wide, and 12’ long.  The footer boards are bolted to the ground posts along each of the long sides of the structure.  This was done to add strength and also to get a better seal along the bottom edge of the roll-open sides when rolled down.  This took a few hours.

Step 7 - Install Ribbon Boards
We chose to install the optional ribbon boards.  Since these boards will not be in the dirt, we used rough-cut, non-treated 1”x4”s 12’ long.  The ribbon boards are bolted to the rafters about four feet above the footer boards on each of the long sides of the structure.  This was done to add strength to the top edge of the roll-open sides when rolled up.  This took about three summer evenings.

Step 8 - Install Rafter Supports
We purchased and installed optional rafter supports.  A “rafter support” is basically a rafter “truss”.  Our high tunnel has 18 rafters, but we only purchased 8 rafter supports and installed them on every-other rafter.  At some point in the future we may choose to purchase and install additional rafter supports on all of the rafters.  The rafter supports get attached to the rafters with clamps, bolts, and Tek screws.  This took about two or three evenings.

Installing rafter supports

Step 9 - Install “U-Channels”
The kit includes aluminum “u-channels” that are 8’ long.  The u-channels are used in conjunction with “wiggle wires” to attach the large clear plastic covering to the framing.  U-channels get installed to the ribbon boards and along the two end rafters.  The u-channels form a continuous perimeter for attaching the clear plastic covering.  This took a couple summer evenings.

Step 10 - Make End Walls Vertically Plumb
Attach a string line between the two ground posts that support the very first rafter.  Then hang another string line down (with a weight) from the tip-top of that same rafter.  What we want is for the two string lines to intersect and touch.  If they do, then that rafter is vertically plumb.  If not, then the top of the entire structure will need to be pulled into the correct position.  Remember the ropes that we used to temporarily stake down the first rafter?  These ropes can be used to pull on the top of the structure.  We found that the structure is still flexible at this point.  Repeat this process on the very last rafter.  If it is also vertically plumb then great!  If not, then you may consider some adjustments.  Hmmm...  

We secured each piece of conduit piping together with Tek screws as we progressed with the construction.  With hindsight being 20-20, we should have waited until now to install the majority of the Tek screws.  This would have made the “squaring-up” process a little easier.

Once the end walls are vertically plumb, then stake the ropes down again to hold it there.  

Step 11 - Construct End Walls
The kit included end walls.  Well kinda.  The kit included two big pieces of vinyl that are hung from the rafter hoops on each end of the structure.  Each piece of vinyl has three zippers.  Once mounted, the zippers can be used to open the “door”.  That’s it.  No additional structural framing.  That design might work for a lot of folks, but not for the winds we get.  We deviated from the design of the kit and built end walls that are considerably stronger.  

For the south end wall, we used six 6”x6” cedar posts (we are USDA organic certified so we can not use treated posts).  Two posts were 16’ long, two were 14’, and two were 8’.  This accommodated the “arched” shape.  The posts were set in concrete, about four feet deep.  We then installed 2”x4” purlins between the posts in the usual “post frame” wall structure.  The vinyl covering was then installed and attached to the purlins.  

Preparing to set posts for south end wall

Mixing concrete

South end wall framing

Notice the ribbon board

Outside of south end wall

For the north end wall, we built a similar structure with cedar posts and 2x4 purlins, but this wall has a 36” steel walk-thru door, and a 7’x8’ roll-up style steel garage door.  For the wall covering, we did not use the vinyl included with the kit.  We used corrugated, single-wall polycarbonate.  

Framing-in the garage door

North end wall

Installing polycarbonate siding onto north end wall

We used vinyl to cover the gap between the polycarbonate and the rafter

North end wall with garage door and walk-thru door installed

All throughout this project we tried to strike a balance between getting things perfectly square, straight, and level; with getting things good enough.  When it came time to mount the two doors we discovered that having things perfectly in place is better.

I would say we have at least another 50 hours into constructing the end walls.

Step 12 - Prepare to Install Clear Plastic Covering
This step includes smoothing-down any sharp edges that might come into contact with the plastic covering -- either during installation of the covering, or after the covering is in place.  Considering the certainty that wind would blow against the structure and relentlessly rub the plastic against anything making contact, we decided to be very thorough with this step.  We either filed-down, sanded-down, or covered-up with duct tape, each and every sharp edge and bolt that stuck out.  We did some of this as we installed the purlins to the rafters, but then had to redo some of the duct tape that became loose.  Altogether, we have several hours into this step.

Step 13 - Install Clear Plastic Covering
This was the big step everyone was looking forward to!  We picked a Saturday with a good weather forecast and recruited four other people (total of six) to help.  The plastic was unrolled onto the ground along one of the long sides of the structure.  Several ropes were attached to the plastic and then used to gently drag the plastic up and over the frame structure.  The plastic is first attached to the structure with “wiggle wires” in the u-channel that is mounted to each end rafter.  Then, along each long side of the structure, the clear plastic is attached to the u-channel which is mounted to the ribbon board (about four feet above the ground).  A section of clear plastic is left dangling on each side in the area between the ribbon board and the footer board.  This will become the “roll-up” side.  Looking back at it, I think two to four additional people would have made this step much easier and safer.  There was one moment when a bit of a wind came up.  I think we all had visions of the wind taking the huge clear plastic sheet and blowing it into the barbed wire fence not to far away.  But thankfully, somehow we managed.  With six people, this took a few hours.

The high tunnel greenhouse with the clear plastic cover on

The interior with the clear plastic cover on

Step 14 - Install the Roll-Up Sides
This step consisted of connecting sections of conduit pipe together to form a single piece of pipe 72’ long (the length of the structure).  This long piece of pipe is then attached to the dangling plastic.  A gear box is then attached to the end of the long pipe.  When a handle is used to turn the gear box, the long pipe begins to turn.  This will, very slowly, roll the side up or down.  “Anti-billow” ropes are attached to keep the roll-up side from blowing in the wind.  This is repeated for the other side of the structure.  This took four evenings.

Step 15 - Bring in the Dirt!
Since we removed the topsoil before construction, we then had the additional task of hauling the topsoil back into the structure.  I’m sure there are a lot of weed seeds in the soil that will be germinating at some point.  We have been watering the dirt to encourage some of these seeds to germinate so we can remove the young weed plants before planting a cash crop.  We will soon be planting a fall, nitrogen-fixing, cover crop that will enrich the soil through the winter months.  We will continue working on soil health, nutrition, and fertility by applying compost, worms, etc.

Some of the topsoil is in

All of the topsoil is in

Expenses
Here is a summary of the expenses:

• High Tunnel Greenhouse Kit $6,000
• Rafter Supports (8)           875
• Shade Cover                     550
• Cedar Posts (12)              1,025
• Garage Door (1)                 300
• Walkthru Door (1)                55
• Polycarbonate Siding            410
• Concrete (48 bags)              108
• Composite lumber                 45
• 1x4s for Ribbon Board            45
• 2x4s for Purlins                100
• 2x6s & 2x8s for door framing    100
• Misc hardware for doors         100
• Misc screws & bolts             100
• Tarps 100
• Vinyl Coated Cable 80

                          Total: $9,993

The total cost (not including labor) is about $10,000 (including our enhancements).  We have been told to expect three to five years of use from the plastic covering before it needs to be replaced -- so that will be a recurring expense every few years.  We hope most other components (other than the plastic cover) will last for many years.  Conservatively, we hope to generate at least $10,000 of revenue per year from selling garden produce grown in this high tunnel greenhouse.  So, the return-on-investment ratio is fairly good.

Benefits
Based on our research, we hope to see many benefits of having a high tunnel greenhouse.  

• Longer growing season
• Protection from bad weather
• Improved ability to manage moisture and temperature
• Improved ability to manage weeds
• Improved ability to manage pests
• Improved ability to manage disease
• Ability to grow some plant varieties that otherwise would not grow in this climate
• A more temperate environment to work in -- especially when the weather is poor outside

Altogether, these benefits will result in a higher quality product, greater quantity of product, easier and more convenient gardening work, and reduced risk.

Summary
This has been a wonderful project to work on in the great outdoors!  We have grown from the experience, and we have invested in our future.  I am oh so looking forward to those cool late-fall and early-spring days being greeted by t-shirt temperatures in the greenhouse!  

Please stop in sometime! We'd be happy to show you our high tunnel greenhouse!

Please feel free to contact me with any questions, comments, or suggestions you may have!

Rick Grosek
Bear Butte Gardenswww.BearButteGardens.com
Rick@BearButteGardens.com

Color Me Blissful!

I have to admit it, I'm a sucker for color.  The brighter and bolder, the better.  So gardening is a fabulous way for me to get a color fix on a daily basis.  To illustrate -- check out these beauties:

Red Romaine Lettuce

Red Leaf Lettuce

Bush Bean Blooms

Rainbow Swiss Chard

Having co-founded and served as the director of a nonprofit arts organization for 7+ years, I really appreciate color combinations that are well done and it never ceases to amaze me how God can paint a canvas with ANY colors and they always look well done.  If you and I threw orange and green on the same canvas, there's a good chance we may not end up with a quality portrait.
 

Burgundy Beans

Moon & Stars Watermelon Vine

Some of the best colors in my gardens are yet to come this growing season:  the reds, purples, greens, yellows, and oranges of heirloom tomatoes; the degrees of orange of the pumpkins; the maturing colors of the peppers; the yellows of the sweet corn; the surprise colors of the sweet potatoes when we dig them late fall; and the reds of the onions.

Green Onion Shoots 

Celery (front) and corn (back)

Along with the glorious colors of the gardens come the shapes and textures of the leaves and vegetables.  I always marvel at the "imperfect" fruits because they are so unique and lovely.  There is nothing lovelier than a lumpy, bumpy heirloom tomato!  It's kind of like that Charlie Brown Christmas tree in the middle of the lot with all of the other perfect trees.

Varying shades of tomato ripeness

Broccoli

Rosa Bianca Eggplant

Head Cabbage

One thing I didn't plant in the gardens this year was flowers. Generally I have as many flowers as I do vegetables, but it was so BUSY just getting the veggies transplanted, I didn't have time to throw in the flowers, too.  But thankfully, it looks like it's all been taken care of for me, because (you know) for every vegetable I get, there was or will soon be a flower to match it.  :-)

Eggplant Blooms

Tiny eggplant emerging from the bloom

Sun in a flower

Two generations of sun in a flower!

Young Pepper

Wenk's Yellow Peppers

Sweet Potato Greens

Baby Summer Squash & Blossoms

Female Pumpkin Blossom

  

June!

Wowsers it's been a while since I blogged!  That usually means one of two things:  I've been pretty busy OR I don't really want to talk about something because it didn't go as planned.  I'd say the former is my excuse this time.  At any rate, let's get caught up a little.

What have I been doing at the gardens since April?  Ummm.......planting.....and then some planting.....and a little more planting.  It's been an interesting mix of really warm 85-95-degree days and really cool 50s to 60s with a lot of wind thrown in and maybe a quarter inch of rain here and there.  All in all it's a pretty dry spring, even for South Dakota.  Hence part of the reason I've been so busy--every time I decide it's time to plant something I MUST first lay drip irrigation because we just aren't getting the normal spring rains.  I usually have a little leniency about getting drip irrigation in place up until about the first of July, but not this year.  So my preference is planting, not laying drip irrigation line; however, I certainly do appreciate the advantages that drip irrigation allows for larger-scale gardening.

Drip irrigation on pumpkins

So at some point this spring as I was laying yet another 100-foot increment of polyethylene tubing I started wondering, just how much drip irrigation line have I put out so far?  It seems like I'm always ordering more tubing and drip emitters, so it must be a lot.  Here's what I've come up with:  1120 feet in the potatoes, 1900 feet in the pumpkins/melons, 900 feet in the tomatoes, 400 feet in the peas/beans, 1400 feet in the cabbages/garlic, 700 feet in the peppers and corn, and potentially another 700 or so feet in the high tunnel greenhouse when it's done.  So altogether that is about 7120 feet of drip tubing and a mile is 5280 feet, so I've laid out a mile plus 2000 feet of tubing.  Sheesh!  And that doesn't even count the new shelter belt.

Killdeer nest in the middle of the pumpkin patch

Planting has been going well for the most part.  I really wish I had more spring greens.  They just aren't as easy to grow without a lot of nice spring rainfall.  I seeded various kinds of greens a few times in different places, but when they didn't really take off after a few weeks, I would re-designate that plot of garden to something seemingly more important like celery or tomatoes or cabbages.  So I am just starting to get some sign of spring greens coming up now and it's already the middle of June.  I may do some close-space planting of greens with intensive water under a section of the new greenhouse when it gets up to see what I can do there.  I guess if all else fails, I can just wait until late summer and re-seed them again for a nice crop in the fall when we will all appreciate them after tomato season is done.

I have a young lady, Kayla, helping me in the gardens this summer as a part-part-time job.  She has a couple other jobs, so I get to see her early in the morning at 6 a.m. or late afternoon, which works out very nicely in the gardens.  I know it seems obvious, but two people can just get things done so much better!  When I'm working by myself it usually takes me 1-2 hours to lay out drip line, then install the drip buttons, then I finally get around to planting 50 to 100 of whatever I'm working on that day.  Usually by then I'm beat and don't get the mulching of the new plants done until Phase II a little later or the next day or so.  When Kayla helps me one of us can be working on the drip irrigation, the other following up with seeds or plants at the appropriate places, and then quite possibly we quickly throw the mulch on and voila! instant garden!  I do have a concern, though.  A few days ago while I was laying drip tubing, she was seeding the squash and she convinced me that we really did NEED to plant 40 zucchini seeds.......and I let her.  So there may be some peer pressure going on here.

The high tunnel greenhouse is a continuing project.  We need to get it finished up very soon, so we'll be really focusing on it for the next week in the evenings and on the weekends.  It's going okay, it's just a first for us putting up something like this and we're trying to make it super strong to withstand all the winds it's going to have to endure.

One guinea and two turkeys of the five bug eaters

We have some new additions to the gardens:  3 young turkeys and 2 young guineas!  After a two-day incarceration in the dog kennel-turned-bird-coop to get them used to me feeding them, they now get daily excursions for many hours about the gardens to eat a nice variety of their favorite bugs.  They are doing a GREAT job.  I've never had turkeys before, so I'm excited to see them grow and watch their personalities.  Right now the turkeys seem to think they are also guineas, so that's kind of interesting.  I think they were all actually hatched and raised by a chicken......so kind of similar to a lot of our present-day human "mixed" families.  :-)

Although the CSA shares have been small the past couple weeks, I think the shareholders are really enjoying them.  I get reports back on how they are preparing and cooking their veggies each week.  So far they have gotten small packages of mixed greens, quite a few snow peas, new potatoes, garlic scapes, and radishes.  I'm looking forward to having the bigger items in the coming weeks like broccoli, early tomatoes, summer squash, and beans.  It all takes time and patience.  I have quite a bit of time, but not always a huge amount of patience!

I've seen this recently in articles I've read and some web sites:  S.O.L.E. Food = Sustainable Organic Local Ethical Food

Please seek out and enjoy your local foods.  There's more out there than your realize!

Michelle
Bear Butte Gardens
www.BearButteGardens.com
Michelle@BearButteGardens.com

 

Soil Blocking

We're heading into the last couple weeks of April and I feel experienced enough with soil blocking to write a little bit about it.  First off.......I love soil blocking!  I really, really do.  I just discovered the soil blocking method this past year, but then I began to wonder, where did soil blocking come from?  Mexico!  Yep, about 2000 years ago an Aztec tribe retreated to the "Floating Gardens" area, which is present day Mexico City, and they devised the Chinampas method of gardening of which the seedling nursery technique (or soil blocking) was integral.  The soil blocks, or chapines, were made from muck which had been dredged from the drainage canals in the Floating Gardens area and dried on piles of weeds.  The chinampero (farmer) would then make a small indentation with his little finger or a stick in the top of the chapines and then drop in a seed and cover the seeds with loose manure.  The chapines were watered until the seedlings were of a size to be planted into the chinampa.

I wanted to try soil blocking this year for several reasons, but the main reason was so I would not have to buy all shapes and sizes of seed trays and then wash them and store them from year to year.  With the soil blocking method I only need one size seed tray, the standard 1020 seedling flat without drain holes.  These will be easy to quickly clean out after transplanting and will all stack together in a small pile.  Use of the clear domes is optional.  Clear plastic wrap works very well in place of the domes during germination.

Standard 1020 tray without drain holes

My other reasons for wanting to try soil blocking included the fact that I wanted to mix my own soil anyway (versus utilizing a prepackaged mixed soil), I liked the idea of the roots of the seedlings being air pruned instead of encircling the seed trays, and I liked the idea of the ease of transplanting the soil blocks into the garden.

Tray of 50 2-inch soil blocks

There would be one reason that I can think of now why I would use plastic pots or divided seed trays in the future for starting seeds---if I decide to sell plants commercially.  Most customers would probably prefer to buy a tomato plant or petunia in a plastic container instead of just getting bare blocks of soil containing the plants.  However, I may be able to convince them otherwise if I ever get to that point.

What I've discovered thus far in my soil blocking experience is that they are very simple to make if you just follow the basic directions.  There are videos on YouTube that show you step by step how to make the blocks.  There are many "recipes" for making your own soil mixture on the internet.  I use the recipe that Eliot Coleman uses in The New Organic Grower with just a slight change.  Once you make one batch of soil and experiment with the soil blocker, you pretty much have it figured out.  If you buy your basic ingredients in bulk, the cost per tray is minimal.  Once I purchased my initial ingredients, I was set for thousands of soil blocks.  A bonus that I had not anticipated with making soil blocks......kids love to make the blocks!  I had a group of middle schoolers come out to the gardens last week and several of the boys had a blast making trays of blocks.

One 12-inch tomato plant in soil block

At this date I have tomato plants in the greenhouse ranging from tiny seedlings to 12-inch plants.  They are all in 2-inch blocks and they are all doing great.  Because of the organic nutrients in the soil mix, I have not needed to fertilize anything and I do not anticipate needing to do so before they are transplanted out into the garden.  Even the largest tomato plant roots are air pruning in the blocks which means when the roots grow to the edge of the soil block, they automatically hold back when they sense air.  As you know, if a 12-inch tomato is in a plastic pot the roots will not only be circling the inside of the pot, but also growing out the drain hole in the bottom.  The worst case scenario with soil blocked plants is if you have the blocks very close together, roots may eventually grow from one block to another, but it is easy to take a knife and quickly cut between the blocks when you're ready to transplant and the plants will be fine.

I am looking forward to being able to start transplanting some of the hardier plants out into the garden next week such as seed onions, brussels sprouts, and cabbage.  I anticipate it will be an easy transition for the plants as they will be moved with their own dense package of soil and placed into the garden where they will quickly spread their roots and thrive.

Micro and 2" soil block makers

One more positive note about soil blocking, watering the seedlings is much simpler than with traditional seed trays or plastic pots.  Those little plastic cells and pots will only take so much water, then the rest drains out and the seedlings dry out very quickly when they have a lot of root mass, especially on very warm days.  Even on the hottest days (and sometimes my greenhouse gets well over 100 degrees) I just fill the flat tray full of blocks with water so that all of the blocks are sitting shoulder deep in water.  They will immediately absorb some water, but what they don't absorb can be left in the tray for absorption later in the day with no chance of the blocks disintegrating or the seedlings rotting.  I've tested this many, many times with the unseasonal heat we had late winter/early spring and the seedlings all did great!

Michelle@BearButteGardens.com
www.BearButteGardens.com

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