Week 1: Jan. 1-4, 2025
A look at: Lisianthus (Eustoma grandiflora)
Hello and welcome. If you caught my Instagram post earlier this week you’ll have read that I’ll be documenting Springhill’s sixth growing season here on the blog, with updates posted every Sunday. It’s not (necessarily) meant to be a teaching resource (because everyone’s growing environment and set-up is different), but rather a glimpse into the process of growing cut flowers here in zone 5b, northern Ontario.
We begin the season, as always, by sowing lisianthus seeds into soil blocks. If you’ve never heard of a soil blocker before, it’s a handheld metal tool designed to create compacted blocks of soil. It takes the place of big, bulky plastic trays (which we still use, for some larger seeds and other plants that grow quickly). I love soil blocking because it allows me to grow a LOT of plants in a small space, and the environmental aspect is, of course, another big reason why I love this method of growing. When it comes to the plants themselves, soil-blocked seedlings experience less transplant shock and are, in general, healthier than those grown in plastic seedling trays. Soil blocking allows “air-pruning” of roots, which means the roots stop growing at a particular stage, versus becoming root bound as is common in trays. When the roots are exposed to air it also means the plant has access to more oxygen which, in turn, creates a healthier, more vigorous plant. If you start a lot of your plants from seed and find yourself short on growing space, I highly recommend this method of growing. Here in Ontario soil blocks can be purchased online at Lee Valley.
This year we’re growing eight different varieties of lisianthus: Arena III red, Arena purple, Voyage 2 light apricot and white, Rosanne brown and black pearl, Falda salmon and Corelli lavender.
I use cafeteria trays (purchased at Ikea), which fit nine blocks of 20, so a whopping 180 plants on one little tray! While there are countless recipes for soil blocking on the internet, I find it’s often hard to source the required ingredients. What I’ve come to realize is that the best soil blocking recipe is made with ingredients that are readily available to me. I try to avoid ordering online when I can, and prefer to source from our local hardware store or co-op, or Peavey Mart and Canadian Tire (in a pinch).
In the past I’ve used Promix mycorrhizae, but this requires sifting first to remove the large pieces of perlite contained in the mix. Because it’s considered a soilless mix (largely peat-based) it’s also quite light, and I’ve found it’s best to use a mask when working with it.This year I’m using an organic mycorrizhae mix I found at Canadian Tire called Golfgreen, which is mostly humus, mixed with a bit of worm castings for an extra boost of nutrients. (It does contain a small amount of peat, which I try to avoid in mixes, but this isn’t always possible). At any rate,the key to making soil blocks that will stand up to months of watering is ensuring the mix is free of things like wood chips, perlite, vermiculite, and that the soil blocks are tightly packed before releasing them on to the tray. Moisture is key!
Lisianthus seeds are tiny and come “pelleted” for ease of sowing. It can take anywhere from a couple of days to a week for the pellets to completely break down, depending on how moist the soil blocks are. Trays are covered with a plastic dome to increase humidity and bottom-watered every couple of days (or daily, if needed). The soil needs to be kept consistently moist in order for the seeds to germinate.
As of today, Sunday, January 5th, there are just under 1,200 lisianthus on heat mats and under lights in our grow room in the basement. Once germination has happened those trays will come off the heat and will grow on under lights with an ambient room temperature of 16 celsius. As we progress through the winter I’ll share some of the problems we sometimes encounter (damping off, stunted growth, fungus gnats) and, once transplanted, the dreaded Fusarium WIlt (and what we can do to prevent it).
The last of the lisianthus (black pearl and brown) will be sown a week from now, with the goal of harvesting these particular colours by mid-late September. And next up? Three varieties of Eucalyptus, my “if-I-had-to-choose-one-plant-to-grow” choice! See you back here next week.
Liisa