Building Compost Heater V2

We receive a large load of horse manure mixed with wood shavings about once every four weeks from a local stable and the material is hot when it arrives at the farm. We are using this material to build version 2 of our compost heater. We encountered some problems with version 1 (see 11/24/08 post) and decided to redesign our concept. In V1 the compost was heavy and put a lot of pressure on the poly and we felt it might break though the plastic. We tried putting in some battens between the hoops and the poly to alieviate the pressure but they were hard to get into place. Meanwhile, the partially-finished pile cooled and froze so we decided to start over at our small, 32x13 heated hoophouse.


The basic plan is to build a pile along the side of the hoophouse and run 300' of 3/4" garden hose through the hot core of the pile and circulate hot water into hoophouse. We are now building the pile and will work out the plumbing details later. We first add an 8" layer of hot compost followed by a 2" layer of fresh chicken litter, mix it in a bit and water it in.

Since our water source is about 200' away and most everything is frozen, it is difficult to get a hose to the project. We have quite a bit of snow now so we're using that for a moisture source. After two or three layers we add more hose on top of the pile in the center. We have placed some 1x2 furring strips between the hoops and the compost pile.

The second picture shows the first few layers of the pile, about 3 feet high, and the hoses running through the pile. We have since added a second hose run and will add one more hose. We'll cover the pile with dry compost or dry leaves and cover the whole thing with a tarp; If we can keep the outside of the pile dry and insulated we should be able to force heat either into the ground or into the hoophouse.




Bucky comes out to the farm (We live a few miles away.) nearly every day. No matter how cold the temperature is, he spends most of his day trotting alongside the tractor, searching for mice (he eats them!), or curled up on his bed in the hoophouse. He is very protective of the farm perimeter and alerts us to every intruder. Yesterday we heard some loud barking and we saw two deer racing across the field in a foot of snow with our dog following behind. When the deer were off the farm, he turned and trotted back to the farm wearing a somewhat smug expression.

Blizzard watch for this afternoon so we better get things in order!

Vegetable Tubs in the Heated Hoophouse

These two pictures were taken in our small (13x32) heated hoophouse. We had a very late start in planting for the winter because our first fall CSA (19 members) kept us busy in the field covering crops and preparing for the winter. But now we are seeding every day but are still two weeks behind where we want to be.

We are attending a winter market on Saturday mornings at Inglenook Pantry in downtown Geneva. It's a small market in its second year, has five vendors, and a group of loyal customers who come to shop every week. Best of all, it's inside the restaurant and Connie and Mark Weaver make breakfast for the vendors. What a treat!

For now we are growing a few greens in pots for the market and the first picture shows some pots of radishes that were planted in December. They are growing very slowly but they ARE getting bigger! If they reach maturity, we should get about three bunches from each pot. Each week we start the quantity we think we can sell at the Saturday market. In about three weeks, as the temperatures start creeping higher we will begin moving the most cold-hardy pots to an unheated hoophouse.

The next picture shows some nice greens but, unfortunately, the farmer-in-charge forgot to put the tag in so we are not sure what they are. They taste good, though! Admittedly, it's a pretty small operation at this point but we need to go for quality and consistency before we try to expand production.

In addition to growing market vegetables we are starting herb pots, vegetables to be transplanted into the unheated houses and a few container peppers and tomatoes to sell at the spring market.

Yesterday we added a layer of hot compost to the big pile on the north side of the house and hope to finish it today when the snow stops coming down. We buried a hose inside the pile and plan to get hot water into the house and create a "hot zone" for tomatoes and pepper plants. Pictures should be posted in a day or two.

Germination Chamber

We are starting to germinate seeds for the new year in our heated hoophouse. We are keeping the temperature overnight at a minimum of 50 degrees. Maximum temperature is maintained at 80 degrees during the day by cracking the door open when the temperature passes 80.

Seed Germination Chamber

This year we decided to try using some of our coolers rather than the large insulated box we used last year. The heat source is a string of 100 conventional Christmas tree lights which use about 240 watts of power. These lights were on sale just after Christmas for only $1.25 a string and one string can provide heat to two coolers.
We put a web tray in the bottom of the cooler to make sure that the lights would be above the bottom in case there happened to be any standing water in the cooler - wet lights could be hazardous to the operator! We bought an
inexpensive digital themomenter at Menards for about $7 and put the probe into the bottom of the cooler. We added lights a few at a time until we could maintain a nighttime temperature between 75 and 80 degrees. It took about 25 of the little lights to keep the cooler 25 to 30 degrees above the ambiant temperature inside the hoophouse. We open the coolers in the morning to check the status of the trays and tubs and remove those that have started to germinate. Everything gets just a bit of water on the top to make sure seeds are moist.

The results have been pretty good and some of the greens have begun to germinate in just 24 hours! By the end of the day we'll have three coolers going and one will be maintained a bit hotter for peppers and tomatoes -- we're beginning to plant some of these to grow large enough to fruit to sell at spring markets.

There are a couple of things to watch for. First, if you take a partially germinated tray out in the morning, it should finish germination but it should be watered twice a day to keep moist. If you leave it in the cooler, you run the risk of some really leggy plants. When we get leggy ones we have been sprinkling a bit of potting soil to reduce the length of the stem. It's also a good idea to do a quick check in the late afternoon to see if any trays or tubs need to be removed.

We have a pretty bad mouse probem so any partially germinated trays need to be covered or placed in an inaccessible place although the mice seem to be able to go just about anywhere! They seem to prefer spinach, sunflower, and cilantro seeds and also baby lettuce seedlings. We are testing various kinds of traps to see which ones work the best.

















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Hoophouse Reflectors Increase Light

We put up a reflector on the north wall of the 70' unheated hoophouse to increase the light and, hopefully, add some heat and also a bit of insulation. We used Panda Film which is 5.5 mil, white on one side and black on the other. A 100' by 10' roll costs about $90 with shipping. The Film was inserted between the hoops and the plastic and seems to be staying in place pretty well.



We had some old white tarps in the barn and are laying them out on the ground to reflect more light into the house. We still have to seal up the doors at the ends before we can tell the overall impact on the heat. Currently a nighttime temperature around zero has left a layer of ice in the water tank and the ice has not completely melted during the last couple of weeks.

We are dealing with some energetic mice and voles which have been nibbling on the roots of some crops growing. They seem to enjoy onion roots and nibble on the lettuce. We are catching a few with mouse traps baited with peanut butter. Bucky The Farm Dog, just visible in the picture above, has turned into a good mouser. There is no "catch and release" with him, it's "catch and eat"! It's a bit odd to see him strolling around the farm with a mouse tail dangling from his mouth and this picture always comes to mind when he comes over to lick your face!

Improvements to Hoophouse

Catarpillar Tent Update

In our last post we described two caterpillar tents we constructed -- one to protect a bed of beans and the other to protect some squash. The tents worked very well until a 45 MPH wind blew one to pieces and the other to the ground. We tried some modifications which seemed to help a bit. The first tents used 10' hoops and a four-foot-wide placement. We lowered the height gradually by moving the rebar further apart. At eight feet wide the tent could withstand the wind pretty well. Another problem was that winds caused the weights (dirt-filled pots) to tip over. We decided to fill some feed sacks with dirt to supplement the pots hoping they would blow and this worked pretty well. We also tried putting hoops 4 feet apart instead of 5 feet.

Now we have a couple of wide tents over carrots and broccoli and the new concern is that the first snow will pretty much crush the tents so we plan to try 7-foot hoops and a five-foot wide bed. We will report again as we improve the design.

Our Four Season Hoophouse

We have set an objective to grow cool weather crops through out the winter to deliver to the local market. To get from three season to four season we need to add heat and light and save as much heat as possible. We also want to do it without using any energy other than solar. To accomplish this objective we have put together the following plan:

Add heat: We are building a hot compost pile four feet high, six feet wide, along the 70-foot length of the hoophouse and right up against the plastic. It seems necessary to be against the plastic to keep that side of the pile moist so heat will be conducted into the house. Our first attempt was a twenty-foot pile built from horse manure and wood shavings from a local stable mixed with grass clippings and other materials. This pile heated to 150 degrees in three days and appeared to be working. The inside plastic felt only mildly warm but that seemed reasonable since any heat that reached the plastic would rapidly diffuse into the house. We uncovered an immediate problem: pressure from the pile was pushing hard against the plastic so we decided to take the pile down, add some battens (See picture. We used 10' by 1" grey pvc conduit) between the hoops and outside poly to reduce the pressure, and then rebuild the pile. Further plans for adding heat:

1. Add white plastic liner inside plastic on north wall to bounce light and heat onto plants.
2. Add white plastic ground cover on ground outside south side of house.

Conserve heat: 1. Insulate north side of hoophous (between outside poly and white liner). 2. Seal all doors and other openings to eliminate all airflow in and out.

Caterpillar Cover-Up

On Friday night we had a light frost in low-lying areas but we received no damage that we could find. Last week we constructed our first "caterpillar low tunnel" inspired by Eliot Coleman's design. We bought a roll of 3-mil std plastic, 100' by 12' ($27), 20 10' brown 1/2" PVC lengths ($25) anmd 40 2' pieces of precut rebar. For the last hoop on each end we pounded in some 1" pipes and used 3/4" PVC to add some stability. We have standardized our beds at 100' long by 4' wide so the tunnel covers 90' of the bed. The tunnel is about 3 1/2 feet tall and access requires removing a pot and lifting the plastic.

At each end we anchored the plastic with 2 40# building blocks. We filled 40 5 or 10 gallon plastic pots with compost to anchor the plastic along the sides. We anchored one end and unrolled the plastic along the windward side. We then worked down the side, one person pulled the plastic over the hoops and the other set the pots on the one foot of plastic along the edge. Then we anchored the other end and then the remaining side.

With a 10 mph wind with 20 mph gusts, total time spent was about 2 hours which included the time spent filling the pots with compost. Filling was pretty fast -- we laid out the pots in a square and dumped about two bucket loads of compost on top and smoothed it by hand to fill the pots. We decided to use compost because we have a lot of it and when it comes time to take down the tunnels, we can just dump the compost in the beds. I believe that one the materials have been laid out, two people can put up a house in about half an hour and take it down in about the same time.

After about a half hour some of the lee side pots tipped over as the plastic billowed out during a gust of wind. We watered the pots to make them heavier, moved them a bit to the center between the hoops and tilted them some toward the tunnel to make them harder to fall over. There were no more problems, even the next day when the wind reached 20 mph. We'll work on some modifications so the tunnel can withstand about 40 mph gusts and a light snow load. We can add heavier side weights, tie the hoops together with a rope purlin and add some tie-down ropes between the hoops. Our steel-hooped houses have been fine with winds of 60 mph.

This first tunnel covered a bed of late snap beans that are about ready to blossom. It's pretty late in the season so we don't know if they will produce anything before we get a hard freeze. We're going to build two more and cover two beds of summer squash that started producing about two weeks ago.

Anyway, we are pretty happy about results so far! Our fall CSA starts in about three weeks so these tunnels will help ensure we have enough produce for our subscribers.

Last week we had some pretty heavy rain, about 8" over three days. In one of our fields we had standing water for several days. Amazingly the eggplant and broccoli seem to be still alive but tomatoes and peppers died within about 24 hours after the ground was saturated.

Peppers and tomatoes in some beds died 24 hours after the ground became saturated. It almost looked like we had had a frost as the tops wilted but next day the plants croaked. "Water wilt" seems to be the technical term.

Today is our CSA delivery and we are really going to be scraping to fill the boxes. Overall, due to a cold spring, germination problems and other issues, we have lost at least half of our harvest. At the Batavia, Illinois, farmers' market last week one vendor said, "I was worried about an early frost but not not. Everything is dead." Pretty much sums up the mood around here.

This week we should start to cover some of our summer crops with temporary hoophouses to help extend the season a bit. Eliot Coleman has an interesting design for a low-cost house that can be put up very quickly. We'll cover some of the winter crops later and we're planning a small fall CSA. Ultimately we hope to harvest all winter for our local market.