hydroponic tulip trial
Hello there! I’m so excited to dig into this post, so without further ado…here we go!
My introduction to hydroponic tulip growing (besides here murmurs here and there in the US) really began last winter in the Netherlands with my good friend and fellow tulip-growing addict, Emily von Trapp of von Trapp Flowers. We were just starting to hear about a mysterious virus in Wuhan. I can remember exactly where I was when I read the news aloud that January morning- sitting on our bed in our funky little room up a funkier set of ladder-like stairs in an adorable crooked canal house in Amsterdam. The news was strange and worrying, but we leapt into our week as planned. The mission: learn as much as we could about commercial tulip growing and network with as many people as possible in the industry in hopes of better understanding our own businesses.
A collection of our hydroponically grown tulips.
We saw a number of farms and growing set ups that week. (Enough to lose count!) Some people were strictly growing outside, in the ground. Some swore by their sandy soil. Others grew in clay soil and used a sort of buried netting to lift bulbs at the end of the season. Some had rolling greenhouses that could warm one patch of tulips after another and thereby create successions of blooming flowers. Some were growing in crates in greenhouses in the winter. Some were growing hydroponically. (About 1/3 of the greenhouse grown tulips in the Netherlands are grown hydroponically.)
We visited a highly mechanized hydroponic tulip farm (more a factory, really) to see first hand how the most advanced, automated tulip growing programs were working. This particular farm sells 60 million tulips per year to supermarkets all across Europe. We were met by a farmer-engineer who gave us a tour of a massive, almost human-less complex of conveyor belts, lifts, and intricate robots that were sorting, planting, moving, storing, growing, and processing the finished tulips. There were people managing only a few packaging-related jobs at the end of the sequence — it seemed like they were doing some quality control and kind of helping the machinery along by lining up stems here or there. Even all the bunching and wrapping was done by machine.
I was amazed by the ingenuity, but depressed by the sterile feeling of the place. The smaller farms we visited before were full of so much joy and pride. I saw that in the engineer, but not so much in the other employees— who must certainly have been wondering when their jobs would be figured out by the programers. The product was also “efficient.” By this I mean that the tulips were being grown as quickly as possible, from the smallest bulbs possible, and harvested as early as possible to keep the whole program moving. It seemed like every little detail had been sorted out. If so many tens of thousands bulbs entered the system at a time, that many (it seemed) came out the other end. There was a continuous and rhythmic cycle.
Still, I was intrigued by all they had figured out, and I resolved to at least try hydroponic growing for myself during our own tulip planting season. Up to this point, my tulip forcing has been done in “soil” (more about that below)..
Soil forcing challenges:
I knew hydroponic growing could be more sustainable for our farm than soil forcing. Because tulips are susceptible to soil borne disease, soil forcing requires some sort of sterile or clean growing medium. Our standby was/is ProMix, which is actually considered a “soiless growing medium.” Some growers use chemicals to sterilize their mediums. Some grow in the soil or own-grown compost they have on hand. Anyhow— it’s no secret that agriculture’s reliance on peat in products like ProMix is bad. The planet’s peat bogs are a limited resource. They take a long time to develop, and thus peat is considered a fossil fuel. Peat bogs are also a huge carbon sink. In short— the less peat we can use, the better.
Soil forcing (for me) costs about $34 per bale of mix for 8 crates of planted tulip bulbs (about 528 stems). I’m forcing about 30,000 tulips now. So- on top of bulb expenses (tulips are not cheap!), labor, and utilities (water, heat, light) I could spend an additional $2,000 on soil mix each year. For these reasons, hydroponic growing can be more financially sustainable, too.
Forcing with mixes can be dirty and dusty. It can necessitate the use of masks and gloves. And working repeatedly with peat (just like tulip bulbs) can lead to allergies and auto immune responses. I’ve seen Emily work with her farm’s own beautiful, rich compost. It isn’t at all like the mix I’m describing. At this time- my farm is young, and we do not yet have a reliable compost heap that I feel comfortable growing tulips in.
Forcing with soil/mixes can also be cumbersome. Once crates are filled and planted, they need to be watered thoroughly and stacked in storage. The stacks take up considerable cool storage space, and they are difficult to move by hand - once watered they are heavy (for me, anyways)! With the proper set up or labor help, moving and storing crates is easier. We saw that in the Netherlands at farms with large “bulb barns” where pallets of soil planted bulbs are easily stacked by forklifts in tall coolers. I found myself limited quickly here on our small farm, by the amount of cold storage space we have. There are creative ways to solve this problem. If you haven’t seen what Emily does with snow bunkers you should take a look at her Instagram feed in the winter.
Benefits of hydroponic tulip forcing:
One of the first things I appreciated about our hydroponic trial was my ability to see the progress in the tulip growth right away. Without the soil I could see how the roots were forming. I could see if a mouse had snuck into a tray and had a nibble. I could see the youngest foliage develop. Photosynthesis can start earlier because the bulbs aren’t hiding in soil/mix.
I’m able to grow more bulbs hydroponically (about 75) in the same area compared to soil planted bulbs (about 66). Hydroponic trays have just about the same footprint as bulb crates, but it is easier to squeeze more in.
I also appreciated how easy it was to move the planted hydroponic trays. Once my bulbs had rooted in a cool space my plan was to move them to a warmer, controlled grow room. I simply poured off the water stacked the trays up, set them out on their new racks and refilled them in their new location. That felt so easy.
Providing proper hydration also felt easier than soil forcing. You can see the water level in the trays and add more water as needed. And there is no barrier between the plant and water. —no work for the plant to do to find water.
The first tulips in my trial started blooming just after Christmas— which felt like a bit of a heartbreak because I had hoped to make it in time for the holiday. But given that I didn’t receive them until November 19th. We did pretty well. I think that with more control over temperatures, I could make Christmas timing work on that delivery schedule. But ideally I’d like the bulbs earlier. I’ll chalk up the late delivery (of almost all our plants and bulbs) this year to Covid complications. Anyhow— what I’m getting at is that the trays for those first plants were emptied early. If I had more bulbs on hand the trays could be re-planted immediately and start to form our own little rhythmic cycle of winter blooms. I can’t wait to dive into succession planting hydroponic tulips next year!
Hydroponic trays are also shorter than bulb crates. They take up less space in storage and less height (if shelved) during the initial growth phases.
Supplies for hydroponic growing:
Hydroponic bulb trays. I have been using black trays with spikes for holding the bulbs in place. They are vailable from Leo Berbee for $15 ea. (Seems pricey to me for the quantity of bulbs I’d like to grow. I’m looking to source lower priced options.)
A water source. We are fortunate to be able to water our farm from our well. Tulips generally require a significant amount of water whether you’re forcing them in soil or employing a hydroponic system.
Water soluble calcium nitrate. I used Jack’s Nutrients Calcium Nitrate. While many bulbs can be forced in just water, (we don’t add any fertilizer to our soil-forced tulips), it is recommended that an aqueous solution of calcium nitrate be used for growing tulips hydroponically. The quantity of calcium nitrate used is measured in parts per million (ppm). It felt easiest to make my solution in one of the many 5 gallon buckets we have here on the farm.
Light. Tulips also require a considerable amount of light to bloom. It is enough light that I felt more comfortable about expanding my bulb forcing operation into a greenhouse tunnel outside only if I added supplemental lighting. It certainly isn’t required for greenhouse forcing. We live pretty far north and have few sunny days in the winter. I’ve been a bit pampered by the control I’m able to maintain in our indoor grow space.
Temperature. Temperature control is probably the most important factor in tulip forcing. Figuring out how to properly care for your bulbs/plants during each stage of the forcing is unique to each farm’s available facilities. Learning how to take advantage of the minimal infrastructure on my farm when I first started forcing tulips was integral to my success with soil forcing— and now with hydroponic growing. I was mentored through that process by Emily at one of her fall tulip forcing workshops.
If you are interested in learning about tulip forcing, you’ll want to see the offerings at The Tulip Workshop! Where Emily von Trapp and I share years of experience in detailed, crop-specific courses for flower farmers.
Join us at:
and learn the art of winter tulip growing.