Greenhouse Management
February surprises me each year with feelings of doubt. As the days grow longer and the boxes of seeds are unpacked and organized for the seeding marathon that lies ahead, I feel a tremor inside of me. Really? I think, as I stare at all of the seeds. Will these really turn into enough food for hundreds of people? I look at the small bags of carrot seeds, and then I poke my head into our walk-in cooler, which still has over 6,000 pounds of stored carrots in it. I look back at the carrot seeds. Impossible. There’s no way these seeds will turn into that heavy pile of food.
As the month progresses, the self-doubt grows into action, which gradually blooms into tentative excitement. There is suddenly so much to do in these few short weeks – and there is so much personal fun to cram in there as well before all of my freedom evaporates into full-fledged farming. Have I caught up with all the friends and family I vowed to this winter? Have I skied enough powder to make up for all of the swims and bike rides I won’t get to do this summer? Have I read enough novels to tide my brain through the summer?
Then March hits. The greenhouse fuel corn arrives and is ignited. Heat mats are rolled out, the first tomatoes are seeded, and onion flats are filled. And the minute the first seedlings pop their crooked, dull green elbows out of the soil, all of my doubt explodes into sheer amazement. Seeds and soil and light and water become food. That’s all there is to this: it just takes organization, patience, energy and the ability to learn year after year after year how to do things just a little bit better.
At the Intervale Community Farm, we grow seedlings in our greenhouse for a 540-member summer CSA and a 170-member winter CSA. Little by little, we’ve improved our seedling and transplant production and our ability to get the work done more efficiently. We still have so much to learn and improve, but here are a few simple strategies we use to produce healthy, organic transplants for our farm.
Creating a Greenhouse Plan
Winter affords us the luxury of time to plan and think about our farm systems. And in the farm season, my brain is a sieve for these details. I try to take advantage of the winter to create as bullet-proof a greenhouse plan as possible – both for me as a reference and for our staff to use independently.
Our farm uses linked excel spreadsheets for our entire crop planning, and that has worked well for us. However, there are several resources that provide crop planning templates, including:
Finding the program that works for your operation is key; but having a solid plan is essential in easing the spring seeding stress. Here’s an example of the greenhouse plan that we use on our farm. This plan is an Excel spreadsheet that is linked to all of our other field plans and seed ordering information with formulas embedded in most of the cells, which makes year-to-year changes easy to implement:
Tray Selection
Finding the right trays for your greenhouse operation is important in tailoring your system so it works for you. At ICF, we’ve loved the reusable 150-cell Plastomer trays, which unfortunately are not currently available (to our knowledge). We also rely on a supply of reusable Winstrip trays which are also difficult to source. Other high quality, reusable tray options that are easier to find are Proptek and Plantel trays.
Many growers use soil block makers, which produce high-quality transplants and don’t require any use of plastic. Soil blocks use more potting soil and would be difficult to handle with the systems our farm already has in place – but they are a wonderful alternative to plastic seeding trays.
Regardless of what system you choose to start your transplants in, the most important things to consider are the physiological needs of each type of transplant, the cost and labor efficiencies associated with different size seedling trays, and how the tray style fits into the rest of your farming system.
Seeding
A determining factor in our tray selection is our seeding method. At ICF, we use a GRO*MOR Wand Seeder with a single wand that was fabricated specifically for our 150-cell trays. We’d increase our efficiency if we upgraded to an E-Z Vacuum Seeder, and it is a likely investment our farm will make in the next few years. On the smaller end of the scale, are GRO-MOR Vibro Hand Seeders and Hand Seeder Sower. And of course, there is the tried and true method of using your fingers to place the seeds in the seeding tray, which our farm does for many crops that we seed a smaller quantity of.
One of the most important factors in our operation for consistent germination is having the flats filled evenly. It makes a tremendous difference to have the soil filled in the cell trays with a gentle firmness to it. If the soil is too fluffy, the seed might get pushed in too deep, it may not receive adequate light, it can get pushed around by loose potting soil, or may suffer from water pooling around it. It’s worth taking the extra time to fill flats properly and not skimping on potting soil.
Watering
This entire article could be devoted to the art of greenhouse watering, but the resonating point for me is that it’s essential to designate one responsible, knowledgeable person to water. Having one person always watering will ensure that there is an attentive set of eyes on the plants. This person also doubles as a pest and disease scout and a person who will alert you to the transplants that are ready to go to the field. Many growers (including myself) like to self-designate as the primary waterer. I love this task because it gives me a steady awareness of the health of the greenhouse while it also forces me to slow down – because watering is one thing that you just can’t hurry.
Cornerstone watering principles:
- Pay attention to the forecast and water accordingly. Most importantly, if there are a cloudy days in the forecast, water as little as possible. The plants aren’t using much water in this weather, and you can foster fungal diseases by creating a constantly moist environment around the plants.
- Use a hose trolley to keep your hose off of the ground. This can help prevent the spread of diseases – and means you’ll be less annoyed by snaking around a hose. Trolleys are easy to build yourself, or you can order a prefab one.
- Pay special attention to the edges of the trays. These dry out quickly and often suffer from lower germination rates and slower growth than the rest of the tray. It’s especially important to water the edge along the greenhouse wall. I try to get the hose directly over the trays so that the spray is perpendicular rather than angled. This serves two purposes: it prevents soil from splashing around and forces me to focus on watering each space thoroughly.
- Trust your instincts. Because I water every day, I know which plants need more or less water and which trays tend to dry our quicker than others. These intuitions guide my watering practice and allow me ways to quickly assess what is happening in the greenhouse.
- Pay attention to the quality of your water. The pH, alkalinity and temperature of your greenhouse water can affect your seedlings, especially more sensitive crops like flowers and bedding plants. It’s worth having a water test done each year to know what you are spraying on your plants. For more information, visit the UMASS extension fact sheet or talk to your own local extension for guidance.
- Designate a time each week when you take a look around your greenhouse looking for problems and checking your sticky cards.
- Remove ANY plants from the greenhouse that alarm you because they are diseased or infested. Ideally, you’d get each problem diagnosed, but this might be cost or time prohibitive, so use your judgment on what you can or can’t tolerate.
- Use your resources. UVM, UNH, UMAINE, and UMASS are a few here in New England that all have excellent support for greenhouse pest management. There is a wonderful annual greenhouse IPM workshop offered in Vermont, New Hampshire, and Maine.
- There are also companies like IPM Labs and Biobest that sell beneficial insects to help combat greenhouse pests. These companies are also great resources for any questions you have regards pests.
- Use the outdoors to your advantage. When I have a problem that I don’t have time or energy to deal with the moment I notice it, I just move the problem plants outside (weather permitting). This allows natural enemies and the flow of fresh air to perhaps alleviate the problem – but most importantly, it protects all the other plants from infection.
Thanks again! Matt