Growing Sunflower Microgreens – Presoaking the Seed

Growing Sunflower Microgreens

Sunflower microgreens are very popular, and for a good reason, they have a pleasant nutty flavor, are juicy, and add great texture to salads and sandwiches.

Growing sunflowers is quite easy, and they don’t take long to mature. A few tricks make it easier to grow sunflower microgreens, and we’ll cover a couple of them in this article. 

The first trick is pre-soaking and treating the seeds to get them germinating.

In this article, we test if it’s better to pre-soak the seeds for 12 hours or 24 hours with a side-by-side comparison grow.

Or is it best to shorten the soak down to only 6 hours?

sunflower microgreens

Pre-soaking and Treating Sunflower Microgreen Seeds

First off, there are as many ways to grow sunflowers as there are people that produce them. We have found a lot of the variability depends on the seed lot. That’s just how it is, and precautions and solutions need to be ready when growing sunflowers.

That’s why we didn’t include sunflowers in our Six Easiest to Grow Microgreens list.

The soft and porous seed shell of sunflowers is the ideal location for fungus spores to attach. Therefore, we recommend treating sunflower seeds with food-grade hydrogen peroxide before soaking or planting.

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We don’t recommend using peroxide from the drug store as it contains stabilizers to extend the shelf life of the peroxide.

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Treating Sunflower Microgreen Seeds

We recommend pouring one teaspoon of 3% food-grade hydrogen peroxide over every 25 grams of sunflower seeds. Pour the peroxide right on the seed and stir the seed around.

Let the seeds soak for 5 or 10 minutes, then pour room-temperature water over them until they’re covered by an inch or so of water.

treating sunflower microgreen seeds

The hydrogen peroxide will break down into oxygen and water, so there’s no need to rinse the seeds before adding the water.

For more information on how to plant sunflower microgreens and how the peroxide reacts when added to the seeds, watch the video How to Grow Sunflower Microgreens at Home.

Additional Articles About Sunflowers

Growing Sunflower Microgreens – Presoaking the Seed
How To Grow Sunflower Microgreens At Home
Sunflower Microgreens Nutrition – Including 5 Awesome Health Benefits

Setting Up the 12- verse 24-hour Soak

This test aims to see if soaking sunflowers seeds for a more extended period before planting will have any effect on the sunflowers as they grow.

We treated two sets of sunflower seeds similarly with a hydrogen peroxide solution and allowed them to soak.

growing sunflowers

After 12 hours, the first batch of sunflowers is planted and placed in a blackout, including a weight on the cover. The second set of seeds continued soaking for 12 more hours before it was planted.

Below is a photo of those seeds. You can see that some of the radicles have started to emerge from the seed.

sunflower microgreen seeds sprouting

Sunflower microgreen seeds after soaking for 4 hours. Radicles have formed.

Below is a photo of both sunflower trays. The seeds in the tray labeled Sunflowers Tully (the tray was for a microgreen workshop) soaked for 12 hours and have been in blackout for 12 hours with weight on them. Notice how level and flat the seeds are.

The tray labeled “48-hour soak” was just planted.

planting sunflower microgreens

The seeds in the tray labeled “Tully” soaked for 12 hours and have been planted for 12 hours. The tray labeled 24-hour soak” was just planted.

Notice that the first tray planted and removed from the blackout period (left tray) also has germinated and that the radicles have not only formed but are growing into the soil media.

A close-up is below (click any photo to expand the size).

radicles on sunflower seeds

Notice that radicles have also grown on the tray planted after a 12-hour soak.

So, it doesn’t matter how long the seeds soak as long as they’re covered and keep moist (as the blackout period does). In fact, we think it’s better to plant them earlier as the radicles on the 12-hour soak have already found the soil surface.

The seeds in the 24-hour soak, although maybe sprouted a bit more, are still discombobulated after planting. They will need to reorient themselves to root into the soil.

As shown in the following two photos, both trays have similar growth. The tray planted after only 12 hours might be further along than those soaked for 24 hours.

sunflower microgreens 4 days after the start of soaking

Sunflowers 4 days after the start of soaking.

sunflower microgreens 8 days after soaking

Sunflower microgreens 8 days after they started to soak. The tray on the left was soaked 12 hours before planting; the right tray was planted after soaking for 24 hours.

Our Thoughts on the Soaking Sunflower Microgreen Seeds

The results of the test show that sunflower seeds soaked for 24 hours may speed up germination. However, seeds soaked for 12 hours planted and placed in a blackout also germinated, and the radicles found the planting media quicker than those that soaked for a longer period.

The seeds soaked for 12 hours seem further ahead throughout the test.

We see no reason to soak sunflower seeds for longer than 12 hours.

Sunflower Microgreen Seeds

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Treating Sunflower Seeds With Hydrogen Peroxide

We’ve planted many trays of sunflower seeds, both untreated and treated with food-grade hydrogen peroxide.

Although some untreated seeds grew great, many others developed fungus attacks (see below).

We now pre-treat sunflower seeds with peroxide every time we plant. 

Since we are wetting the seeds with liquid peroxide anyway, we soak them between 6- and 12 hours before we plant them. 

It seems to work best for us. Even some of the pre-treated seeds occasionally grow fungus. But a quick spray with 3% food-grade hydrogen peroxide kills the fungus, and the sunflowers grow great.

Fungus on sunflower seeds

Sunflower seeds not pre-treated with food-grade hydrogen peroxide tend to grow fungus. Even like this, H2O2 can kill the fungus and not harm the sunflowers.

Our Recommendations For Soaking Sunflower Microgreen Seeds

We recommend pre-treating sunflower seeds before planting. Since these seeds will be pre-treated with peroxide and water, they might as well soak for up to 12 hours. 

Soaking seeds for extended periods doesn’t appear to speed the process up.

Generally, we soak the seeds overnight and plant in the morning or soak them in the morning and plant them later in the afternoon. 

Using food-grade hydrogen peroxide does reduce the chance of fungus growing. If the fungus does appear on the seeds, spraying it with hydrogen peroxide will kill it and not harm the plants in the early growth stage.

Home Microgreens Sunflower Microgreen Soaking Method

We treat sunflower seed with a teaspoon of food-grade hydrogen peroxide per 25 grams of seed. After 5 to 10 minutes, we add fresh water to the seeds until the seeds are covered by an inch of water.

After 6- to 8 hours, we drain and rinse the seeds, then plant them on a soil media and place them into a blackout period. If necessary, the seeds can soak for up to 12 hours.

What is your experience with sunflower microgreens? Do you use hydrogen peroxide and soak your seeds?


  • Todd

    Todd is the founder of Home Microgreens & the Home Microgreens store. He also writes for several other websites, including MyViewFromTheWoods.com. Todd worked at a large farm market, garden & nursery center for 20 years. Somehow he snuck off to become a geologist and professor before coming back to his senses to write & lecture about microgreens and gardening. When not at the computer, he can be found in the garden, trout stream, or mountain trail with his new Springer Spaniel Caden.

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3 thoughts on “Growing Sunflower Microgreens – Presoaking the Seed”

  1. I have been planting organic sunflower microgreens since 2016. I store my seeds in the refrigerator in a sealed bag. I have always soaked my seeds around 8 hours. I have never used peroxide. I had never heard of that until now. I also have never had a fungus issue. I live in Florida and grow my microgreens inside and keep my A/C set at 75 degrees (cooler might be better but i can’t stand being cold), and monitor the humidity which is around 55. Once I uncover them I keep them under regular lights no grow lights (although I am considering it) and keep them under the overhead fan so air is circulating. Thanks for all your info and testing. Anita

  2. I find my sunflowers for micro greens germinate over a long time span, rather than nearly all at once. I soak about 12 hours then plant and blackout in a tray with potting soil or with coir or with soil, coir 50-50. Your thoughts?

  3. I find that sunflowers are an enigma and dialing them in involves multiple factors more so than other microgreens. Each lot of sunflowers I purchase have different “needs” if you will. Sunflower germination is very sensitive to temperature. A matter of a couple of degrees can make a difference. I grow 100% with a coir base with natural additives and I don’t experiment with it on my larger crops. Yes, I play around a lot with different potting mixes but only on a small scale. I find what works best on a small scale and use that for my commercial grow outs. Changing too many variables leads to troubles. I have some evidence that soaking sunflower seeds for a 24-hour period is better than a 48-hour period. At some point, I’m going to plant sunflowers on 2-hour soaking intervals and see if there’s an ideal soak. Currently, I soak depending on my schedule. Sometimes I soak 10 hours, other times is 4 hours. But knowing what is better, or more likely what is worst, would be beneficial.
    My recommendation is to find what works for you and stick to that method and if you change anything only change one variable at a time. That is very hard unless you can strictly control your grow environments. In the summer I grow sunflowers on a 6 to 7-day interval and use a blackout cover that allows some air exchange. In the winter, I’m on a 10-day interval with a tight-fitting blackout cover. In the between seasons, I’m always chasing the temperature swings. Sorry for the long answer because of the variables. The biggest variable is the seed lot and temperature. Soil and soak time may have some effect.

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