Though hoop houses , fictile tunnel andcold framesare a lot more plebeian these days , there ’s another way to ensure a harvest of smart greenness almost all wintertime retentive . It ’s called below - grade trench planting , and it ’s an excellent and inexpensive manner to keep the lettuce , cabbage , tat soi and other cold - conditions crop rolling into the kitchen even when the snow flies .
What Is A Below-Grade Trench Planting?
Where other season - extenders trust on building material to isolate plants from moth-eaten temperature , below - grade oceanic abyss planting rely on the insulating properties of the land to protect plants . Instead of a downfall crop being planted at grime - level and then covered by a protective structure , it ’s planted deeply in the ground , where it ’s protected by the still - warm soil instead .
During uttermost winters in northerly U.S. gardening zones , the ground can stop dead down to several feet , especially if there ’s small blow cover . But , in distinctive winters , even in the north , the dry land will not be fully frozen for a calendar month or two after the steady horticulture time of year finish , if it stop dead at all . Gardeners who utilize below - form deep planting for year - round maturate make use of their still - warm grunge by planting fall and wintertime harvest in a deep deep dug into the soil .
How To Make a Below-Grade Trench Planting Bed
Step 1: Select A Site
To start , take a location that receives full sun for the intact mean solar day . Do not nibble a low - lying area that could become waterlogged . Your trench should be given east to west , so plunk a website that can accommodate that .
Step 2: Dig The Trench
A large - exfoliation granger can prod a trench with a small backhoe or another piece of mechanical equipment , but backyard nurseryman can get the picture their deep by hand . It can be as large or as pocket-size as you ’d like , but make certain you’re able to reach into the nerve centre of the deep easily . If you opt for a large trench , at planting and harvest home clip you might find it comfortable to climb down into the trench to plant and pick , rather than doing it from the surface .
Typically , below - grade planting trenches should be two to three foot rich at minimum . I prefer three to four feet abstruse because here in Pennsylvania we rarely have wintertime where the ground freezes much below a astuteness of about three human foot .
To help determine the frost line in your region , wait at your local building codification to see how deep foundations and support column must be set .
Step 3: Shore The Sides (If Needed)
You need to complete this stride only if you ’ve dug a trench panoptic than about six feet and deeper than four infantry . For large trenches like this , shoring the side with cross braces and plyboard is a good melodic theme . To further insulate deep , wide trenches , you could also line the sides with stubble bales .
Step 4: Prepare The Base Soil For Planting
When you stop digging the land site for your below - grade oceanic abyss planting , you ’ll find you ’ve go away the good soil in a mound to the side of your deep . The filth at the bottom of the oceanic abyss will be less - than - ideal for planting . To prepare the base of the trench for planting , put a few inch of the top stratum of soil that you removed back into the bottom of the trench and ruffle it with two to three inches of finished compost .
Step 5: Plant Your Crops
Any cold-blooded - weather - broad craw can be grown in a below - grade trench planting site , but some pet include the greens mentioned above , as well as cole crop and certain root crops , such as common beet , radish and turnip . Sow the seed into the bottom of the trench in recent summertime or early evenfall to guarantee they ’re already develop well before very frigid atmospheric condition arrive .
Step 6: Cover The Trench When The Time Is Right
The oceanic abyss should be leave receptive and uncovered while the growing time of year stay on . But , as shortly as regular frost arrive , it ’s meter to close in the area to hold back the soil ’s heat . Lay 2 - by-4 boards across the trench every few groundwork and then cover the entire trench with a layer of wooden-headed , clear plastic film or set plastic sheeting . Do not use opaque plastic as it will block light from arrive at the grow plant . spot John Rock or brick around the edges to batten the plastic in place .
Step 7: Mark Or Fence The Site Well
To keep kids , animals and anything else from incidentally come into the deep , palisade it in or post clear signs warning of the danger .
Step 8: Water As Needed
The credit card can be removed whenever you need to H2O , but otherwise , give it in lieu . Once stale temperature arrive , lachrymation will have to occur less frequently , if at all .
Step 9: Pull Back The Plastic On Warm Days (If You Want)
The relaxation of using below - grade trench planting alternatively of cold-blooded frame or basketball hoop houses also get along from the fact that you do n’t have to remove the plastic on hot days because not only does the soil insulate the plants from utmost cold , it also insulate them from utmost heat .
Step 10: Keep Snow Cleared
If you covered your trench with plastic film , the 2 - by-4 crossbreeding accompaniment will assist hold the plastic in situation under a humble amount of snow . But , if more than a few inch of snow crepuscle , on a regular basis brush it off the plastic with a sonant broom . This is less of a concern if you use rigid plastic that can carry more exercising weight .
Once dug , below - gradation deep planting sites can be used for many age , specially if the sides have been shored properly . just total more compost to the bottom when planting time arrives and sow in a new craw .
