This year we’re progressing from “trying out new varieties” to “conducting variety trials” – same thing but with more attention to making growing conditions the same for each variety and keeping track of results. Since neither Lin nor I have the slightest tendency or training toward scientific rigor, we’re looking to the Organic Seed Alliance’s excellent booklet, On-Farm Variety Trials: A Guide for Organic Vegetable, Herb and Flower Producers (download here) for inspiration and instruction.
Here’s the gist: Plant in a location that will provide the most consistent conditions possible – not shady at one end, or different soil types. You want the differences that show up to reflect genetic variations rather than cultural ones. Include one variety you’re familiar with and have already grown. That way if the summer is cold and not one of your tomato varieties ripens until September, not even your old favorite that usually ripens by early August, you’ll know to blame the weather, not the new varieties.
Set up your trial bed with more than one block of each variety, arranging their order so each variety has a chance at an end and middle position to further rule out environmental variables. Plant the entire bed at one go, and care for it the same way – weed the whole bed at once, water every part equally, etc.
Make a list of traits you want to evaluate (actually, do this first so you can design your trial for the information you want to discover), and score your plants at intervals throughout the season, assessing each block separately, not just each variety. OSA suggests using the International Center for Tropical Agriculture’s 9-point rating system: 1=poor, 3=fair, 5=average, 7=good, 9=excellent – with room for finer distinctions in the even numbers. In my spring radish trial, I want to evaluate for vigor, flavor, how long the radishes can stay in the ground without becoming tough and woody, and how well they perform both with frost and with hot days. I’ll plant a batch now to catch the cold nights, and a late batch to evaluate resistance to bolting in hot weather. Then I’ll grow the winner (or winners) for seed.
Spring Radish Variety Trial Plan:
I know what to expect from French Breakfast and German Giant, so they’ll help me evaluate the others.
That’s the idea; we’ll see how real life compares. Already I’ve had to abandon the perfectly planned early lettuce trial. Two varieties did not germinate at all (old seed), and two others, from new seed, germinated so poorly we’ve started them over, while meanwhile the other varieties popped right up and are already transplanted out. Looks like we’ll be trying new lettuces the old haphazard way – which still will provide plenty of useful information about flavor, vigor, and bolting tendencies, not to mention lots of great salads.