Most of us try new varieties in our gardens by picking one we haven’t grown before that looks fun, or has an enticing description. Experimenting with growing something new is one of the joys of gardening, and something I do every year. But sometimes, we might wish to get a bit more organized. Choosing the best performing tomato variety for a main crop used in dozens of jars of sauce should be more methodical. 

If you’ve had trouble getting cabbages to head, or issues with plant diseases, you may wish to undertake a more disciplined trial when trying to find a variety that works for you, in your climate, and in your garden.

What is a Field Trial?

Simply sowing a new variety of sweet corn or lettuce is an informal trial, but we often don’t learn much in the way of what does well in our particular gardens. You might experiment with a new hybrid sweet corn and think it didn’t do well, but not realize or remember it was planted late, there was a cold snap, or it was excessively dry the entire month of August. 

A field trial attempts to provide uniform conditions to showcase differences in the plants themselves, not their growing environment. For example, you might designate one raised bed for a lettuce trial to ensure that all varieties receive the same watering, fertilization, sunlight, and drainage conditions. Planting varieties in different parts of the garden could introduce variables. 

Field trials typically have a control variety that you are familiar with, and then one or more new varieties to test against the control. 

Setting up and running your garden field trial

To get useful information, perhaps not at the scientific level but at the practical level, we’ve got to define the experiment, design it, and properly set up and implement the trial. And of course, take notes along the way.

Define your test

Before the seeds go in the ground, you should have a goal in mind for the trial. It might be the best-tasting lettuce, the earliest tomatoes, or the sweetest carrots. You might also be trialing for flower color, size, disease resistance, growth rate, or any other trait you can think of. Select one or maybe two parameters you’d like to test for. 

Choose a control and a few test varieties

To give you a benchmark to measure against, you ideally need a control variety you’ve grown before. Including a familiar variety in the test helps you fairly evaluate, even if the growing season was challenging or excellent. It evens out any nature-induced difference from year to year, and provides an easy reference on whether a new variety was better, worse, or the same for the trialed trait. 

If you were looking for an early maturing sweet corn, but didn’t plant a control variety you’d grown before, a warmer-than-normal season could have you believing every corn variety you tried produced earlier than others you’ve grown previously, when in actuality it was the weather that sped up the process, not the variety. A control variety helps you separate a bad variety from a bad season.

Keep it uniform

If you were running a foot race against your peers, you would want everyone to start at the same time, finish at the same place, and run the same course to keep it fair. The same idea goes for plant trials. 

• Plant all varieties on the same day so any differences in maturity timing are valid, not artificial. When planted on the same date, all plants experienced the same weather conditions throughout their growth. 

• Choose a plot large enough to plant all the varieties to be trialed together. Soil conditions can vary widely across a garden, and even from one raised bed to another. 

• Remember to take mature plant height into account for tall crops. Corn height can vary several feet by variety, so plant the taller selections where they won’t shade out a shorter test variety.

• Keep the watering schedule the same for all varieties. This is easy with a soaker hose or sprinkler, but can be difficult with a hose and hand watering. If you are watering with a wand on the hose, you can even out how much water each plant gets by counting out the seconds. For example, each plant gets watered for seven seconds, or whatever time is needed. Keep it the same for every plant in the trial.

• Fertilize with the same product and amount. If applying compost, do so in a uniform fashion.

• Try to perform the same diligence in pest management across the entire test plot. While you may find that one variety is less susceptible to pests than another, they all need the same level of effort to make things even.

If you have space, plant several of each variety. A one-plant trial is easily skewed. Even two or three plants per variety meaningfully improves your results. If all three plants did well, that’s a thumbs up. If two did well but one didn’t, it might bear further scrutiny. If all three did poorly, that might be a thumbs down.

If you have the space, try to avoid planting a test or control variety at the edge of the bed. Border-row plants behave differently because they lack competition on one side, which can inflate their performance. They will likely yield or bloom differently. 

For a trial with carrots, you might plant a five-foot row of each variety in the middle of the bed, and a row of spinach on the edges to prevent the edge effect from throwing off your results. Planting in this manner prevents any one variety from gaining an advantage, and lets you test for overall yield (many plants for an average) as well as taste or timing.

Keep accurate records

Ugh, paperwork. But, unless you have a perfect memory, a notebook with the variety, seed source, planting date, pre-planting seed treatment, planting methodology (spacing, depth, etc.), fertilizer applications, and a weekly status update will greatly help. 

If that all sounds like a lot, remember that a visual garden journal can be as easy as grabbing a few pics with your phone. Check out our article on how to keep a garden journal by snapping pics here. You’ll have a time-stamped visual record to refer to at the end of the season.

Keep notes not only on the conditions, but also when pests showed up, if the weather was unusually dry, if one variety wilted quicker than another, and any other differences you spotted. If you are trialing for taste, get as specific as you can. Was it crunchy, sweet, bitter, tasted too strong, or too bland? Did you like it better than the others?

To get you started, here are a few important parameters to record:

• Key traits to record for vegetables: germination time and success, severity of transplant shock if applicable, days to flowering, days to harvest, yield, disease resistance, flavor, and shelf life.

• For flowers add these to the vegetable list above: days to bloom, vase life, color trueness (to the advertised shade), and rebloom percentage if applicable.

Extra tips for home garden field trials

Keep in mind that one season's results reflect one season's weather. If a variety wins your trial by a large margin, it's a strong signal. If it wins by a narrow one, consider running the trial again next year before making it your go-to. Of course, taste trials can still be conclusive after a single year.

• If trialing sweet corn, be aware that supersweet (sh2) varieties are sensitive to cross-pollination from other corn types. They’ll need to be separated from standard sweet corn plantings by about two weeks so they don't silk at the same time.

• If your gardening friend has space, ask them to perform the same trial in their garden. Not only is it fun to compare results, but you might get extra confirmation about significant differences.

• Label everything thoroughly. I make a hand-drawn map in addition to labeling stakes out in the garden. Stakes break off, become illegible, or just flat disappear. 

• Remember to choose varieties matched to your local climate and conditions. 

Trying something totally new (to you)

But what if you haven’t ever grown beets, carrots, or marigolds? Do you need to grow just one variety this year to serve as a control variety for next season?

No, you can still adapt the trial method, even if you haven’t grown that type of plant before.  Utilize the same trial methodology; you just won’t have a control variety to provide a benchmark. 

For example, if you haven’t grown beets before, pick three different varieties and follow the above methods. You’ll still be able to pick which of the three worked out the best for you with confidence by using the plant trial method.