Have you ever wondered if you have what it takes to grow food year-round using hydroponics?

Step inside a working farm and explore what it’s like to be a hydroponic grower! Fiona with Rocket Greens will document what it’s like to seed, transplant, grow, and harvest in a Growcer modular farm*. Plus, how Rocket Greens distributes their harvest through their subscription box which you can understand by following Fiona on a distribution day.

Transplanting

Of the 600 seedlings we prepare, only 375 will be transplanted into the Growcer. We try to have a good, healthy variety of seedlings so we can choose the happiest ones to move into the growing area.

And some of you might be thinking - are we throwing away perfectly good seeds? When it comes to seeding, getting a 100% germination rate (the number of seeds that sprout) is like winning the lottery. We always plant extra seeds to ensure we’re always making the most of our growing slots.

The other bonus is that having extra seedlings gives us some flexibility with what goes into the Growcer system. If our spinach seedlings look fantastic and our lettuce looks poor, we can plant an extra half-shelf of spinach in lieu of the lettuce.

“Having extra seedlings gives us some flexibility with what goes into the Growcer farm.

If our spinach looks fantastic and our lettuce looks poor, we can plant an extra half-shelf of spinach in lieu of lettuce.”

All seedlings spend two weeks in the seedling area, with a few exceptions. We leave our herbs for an extra week or two to allow them more time to mature. Parsley, mint, and cilantro in particular can take a while longer to germinate than our leafy greens – but once they grow, they grow fast!

Newly-planted seedlings take four weeks to mature fully.

This parsley seedling spent four weeks in the seedling area before transplant.

Before transplanting, we fill in this chart which helps us to map out where to plant each variety.

We’ve found the placement of our varieties does matter!

Since warm air rises, we’ve learned the top shelves are usually a bit warmer than the lower ones. In the winter, the front of our container where the air intake is, will be a few degrees cooler than the back.

So we plant accordingly: brassicas (like kale and bok choy) go lower and in the front third of our container, and lettuces and herbs towards the back.

Once we have made our plan and checked the condition of our seedlings, we are ready to transplant. We slide each flat of rockwool into a solid tray, one without holes to keep any excess water from spilling on the floor.

The tray with seedlings and holes (to allow for water to drain) is moved into a transplanting tray without holes so it’s easier to transplant without getting the floor wet.

We like to pay attention to a few things when choosing which seedlings to use.

Number of sprouts: For any double-seeded varieties like kale, spinach, collards or mustard, we choose seedlings that have two sprouts instead of one.
Roots: Healthy, long, white roots will give our seedlings a good shot at becoming big and strong adult plants.
True Leaves: “True leaves” show that the seedling is maturing well. Blade-like leaves called cotyledons (caw-tuh-lee-duns) appear first, followed by the spinach’s true leaves. They are small, paddle-shaped leaves that look like mini versions of grown-up spinach leaves.

When transplanting, I plant back to front to avoid leaning on freshly planting seedlings. I also pick a handful of seedlings in my left hand and transplant them with my right - I find I go faster this way.

Long roots are hard to deal with, because they are delicate and difficult to dangle into the seedling’s spot. My strategy is to spiral the roots on the tray’s lid so all the roots make it in without breaking.

How Fiona spirals the roots so they fit in the growing slot without breaking.

Each time I choose a seedling, I make a quick decision on whether to plant it or not. If it’s a great-looking seedling (Grade A), I transplant it right away. If it’s okay-looking (Grade B) I place it back in the tray to use later. If it looks poor or hasn’t germinated, I toss the seedling into the compost bin beside me (Grade C, for compost!).

An example of each “grade” of seedling. Grade A seedlings are ready for transplant!

This photo of spinach seedlings shows an example of each grade:

A – This seedling on the left is beautiful! It has multiple sprouts with several true leaves and long, healthy roots. I would plant this one for sure.
B – This seedling on the bottom looks healthy, but not perfect. There aren’t too many roots growing through the rockwool, and only one of the two seeds planted has germinated. I’ll set this one aside in case we need it.
C – The rockwool on the right doesn’t have any germinated seeds in it, and will go into the compost.

When transplanting we place each seedling carefully, far enough that roots touch the flowing water, while not pushing the seedling too far in. The top of the rockwool is raised slightly above the tray lid to prevent it from falling through.

These transplanting nuances aren’t top of mind unless you are someone who has spent many, many hours in a certain Growcer farm. The more time I spend as a grower, the more I take in. Each plant variety, climate, location, and season will have its own quirks, and as growers we learn to roll with the punches.

Trying to adjust and adapt makes growing hydroponics feel like a unique puzzle to solve. Our team is always looking to learn more so we can become the best plant caretakers possible.

*Because Rocket Greens was Growcer’s first customer, their farm represents an older version of Growcer’s modular farms that uses nutrient film technique (NFT) instead of shallow water culture (SWC) to grow greens. For the latest farm specs and yield data, download your comprehensive guide to Growcer’s farms.

Day in a Life of a Grower: Transplanting

Transplanting