Winter Calla Production
Hi grower—We received a nice calla growing question from a customer this week and we think the info might be helpful for you, too!
Q: “I'm interested in mid-winter calla production. Are rhizomes something you could provide during this timeframe? I'd love to start some right now even! Alternatively, could we hold rhizomes over summer and plant them late in the year?”
A: Cool! Let’s talk about how we can make that happen:
Winter shipping for callas is tricky because the rhizomes are sensitive to cold temperatures. You shouldn’t have calla rhizomes shipped to you if there is a chance they might freeze (They should be treated like dahlia tubers).
We are scheduled to receive a shipment of Dutch calla rhizomes to our warehouse in late February/early March. They are part of our spring bulb collection and that’s the next time we’ll have callas available for growers. We’ll be able to ship to customers as soon as the weather permits for their zones. We’ll rely on customers to tell us when they’d like their orders shipped. Customers can request their own shipping dates when they make draft orders and submit them to us, or send us a note with their preferred shipping date.
We can also look into receiving some calla rhizomes with our fall 2026 shipments to send out before it gets too cold. That would be the simplest way to achieve winter calla blooms. The rhizomes could be planted on receipt and grown indoors under lights. We grow callas in our basement grow room in the late summer and early fall.
Alternatively, you can grow callas in the summer, allow them to enter dormancy (which happens when temperatures drop below about 50F), store them in a cool, dry place for 2 to 3 months between 40 and 50F, and then force them indoors at room temperature with light in the winter time.
It can be difficult to dry store the bulbs all summer long and wait to plant them until the fall. Calla rhizomes can be prone to mold, rot, or soft spots if they experience too much moisture or dry out too much. We caution growers to enter very carefully into dry storing bulbs for that length of time in the summer. (Again, approach their storage in a similar way to dahlias.) Callas are more traditionally dry stored in the winter when the temps are cooler and the air is less humid for most growers. A safer summer storage route may be to plant them on receipt in soil in containers and keep them dormant between 40 and 50F until you're ready to grow them.
Note: Calla rhizomes like a little hormonal encouragement before you re-use them. They should be dipped in a gibberellic acid solution. It sounds scary, but it’s a common practice and not difficult.
Here is the process:
To treat calla lily (Zantedeschia) bulbs with gibberellic acid (GA3) for increased flowering, soak the tubers/rhizomes for about 10 minutes in a solution, typically around 500 ppm (parts per million), then plant them immediately, ensuring good drainage. The treatment stimulates uniform sprouting and more flowers.
For more information on cultivating a great calla crop, see this post.
Have your own growing question? Reach out and let us know. We’ll do our best to help you.
Cheers,
Linda
