an interview with Farm Manager Carrie Hargrove
Let’s start with your motivations for building a greenhouse and the results you’ve seen. Obviously, a greenhouse enables a longer growing season. But what other benefits do you get from having one?
It’s true, we can start seeds inside in a growing medium many weeks earlier than we can outside in the soil. This is true especially in years when we have a long, cool spring, when the soil warms up very slowly. And there are some plants, like bulb onions, that germinate better when they are seeded indoors, where they get more consistent temperatures and moisture.
Likewise, some plants benefit more than others from having that consistency while they’re getting established in their root system. For plants like that, you just can’t get the same results with direct seeding. So those are all general benefits to using a greenhouse.
There were a few ways that building one benefited CCUA in particular, too. For the past few years, we have been lucky enough to be able to start a limited number of seedlings in borrowed greenhouse space here and there. But having a greenhouse on the farm at Smith & Fay involves less time (and cost): we don’t have to go to another location to start the seeds, tend them, and then bring the seedlings to the planting site. Instead we are starting the seeds where our planting materials and tools are stored, where our compost is developing, and where most of the seedlings will ultimately be planted. (Many of the seedlings are destined for Opportunity Gardens or satellite gardens, but most of them go into the ground at the main farm.)
And having our own greenhouse means that now we can plan from year to year on a consistent amount of greenhouse space, which makes the planning stages during the winter easier. Having this space also means that we will no longer need to buy substantial quantities of starts like eggplants, tomatoes, and peppers from commercial growers. We just didn’t have the greenhouse space to start them all from seed for ourselves in the past, but now we do.
Have there been any significant challenges or drawbacks to working with this greenhouse on site?
The main issue is that anytime you work with plants in a closed environment, the pest insect populations can really boom — especially if you include compost in the seed starting medium, which we do. At our particular location, the big pest is the “roly poly” or pillbug. They can be pretty destructive to seedlings. So we control them with sprinklings of diatomaceous earth on the seed starting medium and some of the transplanted seedlings. It’s a powder ground from silica deposits formed by the fossils of plankton; the powder scratches and pierces the insects’ exoskeletons and causes them to dry out and die. (But it isn’t poisonous and is even safe to eat; it would only bother a person if some of it were directly inhaled.)
Let’s talk about the structure of the greenhouse. Did you follow a particular blueprint, or was it a more basic project of measuring and building to fit a certain space?
Well, it was a little of both. We did have a blueprint, because we wanted to build a passive solar greenhouse, and that requires specific proportions, configurations, and materials. But we also wanted to limit the footprint of the building. The design we used was developed by MU’s Bradford Research and Extension Center, and there is a lot of helpful information available online, including the building plans.
That design explains the proportions of the building, and the builder can adjust the measurements to suit the space available and the needs of the project. The length to height to depth of the building should be 2 to 1 to 1; our building is 20 feet by 10 by 10. We also built the greenhouse on post risers that add about 18″ beneath the floor, because we agreed not to pour any concrete slabs or build any permanent structures on the land, which is on loan from Mark Stevenson of REMI. The building faces south, so it faces Smith Street; the long axis of the building is aligned east-to-west.
Watch for Part 2 of the interview!