Welcome to part 3 of our special series on year round indoor salad gardening. In the past two parts we’ve covered choosing a location for the garden, building shelves, picking containers, mixing soil and assembling supplies. What’s left? Growing. As I mentioned in part 1 of the series, I plan to grow micro greens in my window as well as some potted greens under grow lights. This post focuses on micro greens. (The grow light set-up will be the subject of a later post.)

So far, we’ve used the method outlined by Peter Burke in his book, Year-Round Indoor Salad Gardening: How to Grow Nutrient-Dense, Soil-Sprouted Greens in Less Than 10 Days (Vermont, Chelsea Green, 2015). You can read an interview with Peter Burke here.

You can find part 1 of the series here, and part 2 of the series here.

How to Measure and Pre-soak the Seeds

Burke’s book has tables to help growers figure out how many seeds are required to fill containers of various sizes. I found his measurements for the number of seeds were accurate and fairly easy to figure out, even for odd-sized containers.

I got tired of always having to look up the measurements though, especially when I had a large number of containers to plant. So I simply spread the seeds around on the bottom of each empty container to figure out how many I’d need – a much speedier method.

Before I could plant the seeds, I had to soak them. That’s when things got really fun.

While buckwheat and peas responded well to an overnight soak in water before planting, sunflower seeds did not. Germination rates were uneven and many didn’t germinate at all. My first question was: did I soak them for long enough? Many growers soak sunflower seeds for at least 12 hours, some 24. Still others let them sprout before they plant them. But when I planted my seeds, every single tray developed mold.

A little online research revealed that sunflower seeds are some of the ‘dirtiest’ seeds, ands need to be disinfected prior to planting lest they encourage the growth of mold in the planting trays. After 2 failed plantings of moldy seeds with uneven germination rates, I decided to try disinfecting the seeds along with a longer soak period.

When I took my woes to Instagram, one of my fellow gardeners gently suggested that growing sunflower micro greens sounded like a lot of work. The sub-text of this was: why don’t you stick with easier to grow crops?

She was right. If the darn things weren’t so delicious, I’d probably have abandoned growing them right there and then.

Instead, caught in the grip of hyper-focused eagerness, I assembled a third batch of sunflower seeds, soaked the seeds for 10 minutes in 3% food grade hydrogen peroxide PRIOR to adding water. I used a ratio of 1tsp of hydrogen peroxide for every 25 g of seeds. (More measuring. What a pain!) To this brew, I added room temperature water without rinsing the seeds and let them soak for 12 hours. After this first soak, I rinsed and drained the seeds then put them back in room temperature water to soak for another 12 hours.

What happened? Keep on reading.

How to Measure Soil and Fertilizer

Burke’s tables worked well for measuring out the compost and fertilizer that form the bottom layer in each container but were much less accurate for soil. My workaround? Fill each container with 1-2 inches of soil after spreading out the fertilizer and call it a day.

Plant the Seeds

Burke asserts that containers can be planted in just minutes a day. I timed it. It took me 25 minutes to fill the containers with fertilizer and soil, plant the seeds, clean up and put away my supplies. Burke recommends planting a few containers every day but given my speed, it’s more time effective for me to sow once a week instead. I’ll aim for 4 or 5 containers per week (we extend our salads with seasonally available produce).

Perhaps I’m just new to the technique but sowing took the bulk of this time. Seeds aren’t pushed into the soil but are spread out evenly on top. This might be possible with dry seeds but the wet seeds just kept clumping up. Instead, I sowed them individually by hand. Peas were super easy, sunflower seeds? Not so much. (Buckwheat was the easiest crop to sow.)

Seed Maintenance: To Germination…and Beyond

Burke’s instructions for germination are to apply soaked newspaper over the containers and place them in a dark place until the sprouts are 1-1 1/2 inches high. This 3-5 day ‘blackout’ period simulates the darkness normally provided by soil. The newspaper must stay wet so the germinating seeds stay moist. Once the sprouts push up the paper, it’s time to remove it and bring the plants out into the light.

The newspaper fell apart when I soaked it for the 10 minutes suggested so I cut the time in half. Just as Burke warned, the newspapers had dried out completely by day 2. This was easily remedied with a mister. The peas and buckwheat germinated fine under wet newspaper. Guess who didn’t?

The sunflowers.

Yes, our dear friends just had to be special. Not only were they slow to sprout but every single seed tray developed mold.

Sunflowers: Take Three

Besides the perennial mold, the growing tails of the newly sprouted sunflower seeds did not drill down into the soil like the peas and buckwheat did. They sometimes wandered up towards the air, dried out and died. A quick online search showed that most growers tamp down their soil before planting, then stack their growing trays on top of each other to weigh down the seeds in order to force them to grow into the soil.

Because of the mold problem, I replaced the sodden newspapers with damp, reusable bamboo paper towels. These can be washed after every planting and then recycled in the compost bin at the end of their useful lives. I wrung out the towels before putting them on top of the seeds to avoid soaking the soil, and placed them the the cupboard over the fridge for the blackout period. I uncovered the seeds on the third day to check on them.

What did I find?

Every single tray had sprouted mold and the germination rates were just as slow and uneven as the first and second batches.

Meanwhile, the peas showed no signs of mold. The peas and the buckwheat seeds sprouted quickly and grew bumper crops. Guess which micro greens get the gold star?

Decisions, Decisions

By now, I’d expanded my research beyond Burke’s book and discovered other micro green resources. (Bootstrap Farmer offers a good online resource for new growers, and you can browse your local library for good book titles.) No one book or resource can ‘do it all,’ or predict every problem a grower might have but I think it’s fair to say that growing sunflower micro greens can be harder than growing pea or buckwheat micro greens. I utterly failed to grow a lush crop of sunflower micro greens, not just once, but three times.

And I’m not alone. A quick survey of internet articles shows that many experienced growers too, have wrestled with growing sunflower micro greens successfully. Like them, I’m no stranger to organic gardening. It’s a good reminder that some crops take longer to learn how to grow than others. It doesn’t matter what level of experience you have or how many years of gardening you’ve got under your belt. When things don’t work out, it sometimes makes more sense to pivot.

I haven’t given up on growing sunflower micro greens but I’m putting them aside…for now.

Instead, I’m going to put in some time learning how to grow easier micro greens like peas, buckwheat, broccoli and kohlrabi. Is it my goal to have a fridge full of homegrown greens every week or do battle with a difficult-to-grow crop?

I’ll let my stomach make the decision here.

A final note:

Keeping a cool house will definitely affect the growth rate of your micro greens. Our house falls firmly into the ‘cool’ category, so I have yet to grow a single crop of micro greens within 7-10 days. It takes 12-14 days for my crops to mature so I’ve revised my growing schedule. If I sow 4-5 containers of crops every 5-7 days, we’ll be able to enjoy fresh greens every week by week 3.

The experiment continues!

Cost

$40 – seeds (1KG EACH peas, buckwheat and sunflower)

$20.99 – 946 ml 3% food grade hydrogen peroxide

$20.99 – 946 ml pure Castile soap (diluted with water and mixed into plant sprays and cleaning sprays)

$81.98 – Total

You could save money by eliminating the hydrogen peroxide and/or Castile soap. I’ll use the hydrogen peroxide to disinfect peas before soaking from now on, as they are also considered ‘dirty’ seeds.

One bottle of Castile soap lasts for months and virtually eliminates the need for any other household cleaner or insecticide, assuming you make your own sprays.

My next challenge will be to keep to a weekly grow-and-harvest schedule. I’ll be back with pictures next month.