I just finished planting my small strawberry bed and thought I’d share the process. The planting bed is about 30"x20’, in a 48’x24’ unheated double inflated greenhouse. I put down 160’ of heating cable in the 50 sq foot space, most sources recommend 3-4 feet of cable per square foot so I may be a little on the low side (but generally these sources don’t specify watts per foot so…). The heating cable is a HIRD de-icing cable, it does not have a thermostat built in. Make sure you have plenty of landscape staples for this job. Initially, I was running low so I made some spacers out of drip tape (later I found some more staples and spaced things out better than in the pics). This cable was not a loop like another soil-specific cable I worked with before–I found this cable easier to work with and more durable feeling. It draws 5 watts per foot and I’m running it 10 hours a day at the moment (so 8kw/day).
I replaced the soil, top dressed with a couple inches of compost then laid the drip tape. The cables are 4-5 inches below soil surface, maybe a touch deep but that compost should compress. Black plastic over the tape, row cover low tunnel over that and done. I fit 48 day neutral Seascape strawberries in the bed, staggering the rows. This was my first time working with dormant, bare-root strawberries and my first time planting through plastic. Thankfully those roots were very resistant to my mangling. I do wish I had bought the plasticulture planting tool the vendor advertised. I settled on a wiggle-a-metal-ruler technique that worked ok.
I tested the soil temperature above the heating cables and here’s what I found–Air temperature in the greenhouse was 41F, and the cables had been running for just over three hours–everywhere from 49.5F to 69.5F. Center of the bed had the highest readings and (strangely) the edge closest to the center of the greenhouse had the lowest readings. So maybe I should have spent even more time trying to get the cables more evenly spread. Hopefully more even soil moisture can even those numbers out.
I’m hoping these plants can produce around 1.25 pounds a piece over the course of the season which should get me close to a quart and a half per week (total for the bed). Not sure if any growers on this forum have gotten close to the those numbers? More planting to come but without more heating cables I’ll need to wait a bit.
Sorry the order of the pictures is all mangled.