One of the frustrations of creating so many amazing new baptisia cultivars is the difficulty in getting them propagated to share. The propagation part of baptisias is actually easy, but it’s the overwintering of cuttings that is not. We root our baptisia cuttings in 48 count cell packs early in the growing season, and by summer, they are growing vigorously. The problem is getting them to survive through the first winter. After the first winter, there are no further survival issues.
What we noticed starting several decades ago, is that in spring, when these rooted cuttings should be starting growth, nothing emerged from the crown, despite great white roots and a solid crown. For some reason, the rooted cutting often failed to develop eyes or growth buds for the upcoming year. Repeatedly, we would wind up with a great looking pot of roots, but no above ground plant would ever emerge. In the first image below, you can see the remnants of the previous years stem, but there are no new buds for growth.
We concluded that despite getting what appeared to be great growth during the previous summer, the plants were still not setting buds. First, our experimentation found that the survivability of rooted cuttings differs dramatically between cultivars. Secondly, our friends at Walters Gardens determined that the earlier the cuttings are taken, the better the survivability. Based on their recommendations, we now put baptisia pots in the cooler in fall, and bring them out mid winter to force new growth, and take cuttings. This certainly helped, but wasn’t the complete solution we needed.
One of our attempts to overcome this no growth bud problem, was to transplant all of our rooted cuttings into deeper, 5 gallon pots for the summer/fall. As you can see below, the percentage of rooted cuttings that survive and develop buds has indeed increased dramatically. The pink shoots are the growth buds that are just beginning to expand this week
Below is one of the rooted cuttings just removed from the 5 gallon pot. It appears that the extra root run due to the container depth, allows the plant to produce more food, which seems necessary for bud formation.
The final experiment we did before we closed our tissue culture lab was to root baptisia cuttings in agar. This was a tremendous success, and had we been able to financially keep the lab operational, would solved our baptisia production issues. Below is a rooted cutting from the lab. So, why did this work? We’re not 100% sure, but theorize that the smaller size of the cutting, combined with those cuttings producing more basal growth seems to have contributed to a much higher overwinter survival percentage. We have shared our recipes for success with other labs in the hopes that more gardeners will have access to these amazing new vegetatively propagated baptisias.
Wow. I found this blog post about baptisia propagation fascinating. I think the general public has no idea how much work and experimentation go into trying to produce healthy plants at a reasonable price that would also allow the grower to earn a profit. Thanks for a good read.
So true.
Interesting info. Perhaps growing out Baptisia in ‘deepot cells or treepots” is worth a try? I haven’t had much luck in NC zone 8a with Baptisia australis planted in a sunny mixed bed where the soil is well-draining but fairly shallow, being built over hard packed red clay, soil depth above clay is 6 to 8 inches on that end of the bed, But this could also be from high competition in the densely planted mixed bed where the surrounding plants are thriving. Perhaps Baptisia australis var minor would be better cultivar for these conditions or I could bite the bullet and create a deeper less densely planted bed and give Baptisia another try. I’m also giving our native Thermopsis villosa ‘Carolina Lupine’ a try this spring in the same bed for comparison.
Any suggestions?
Thanks,
Greg
Baptisias aren’t great with lots of competition, so that’s a likely culprit. They are also very deeply rooted, so good soil preparation to 1′ deep really pays off. It’s really never a good idea to plant over hard packed clay without a good interface layer, where the packed soil below and the good soil above, are thoroughly mixed. We like Baptisia minor (formerly B. australis var. minor) much better than B. australis due to its small form, and larger flowers. Thermopsis, like baptisia aren’t great with dense competition.
was fun to get the plant rooted in the lab!
His do you root in agar? Was it pure agar or mixed with soil? Please explain. I have only used it in shallow Petri dishes. Fascinating article. I am sorry you couldn’t maintain funding for your lab.
Thank you,
We didn’t actually grow roots on the baptisias in agar, so cutting were stick directly in the agar. The agar contained a number of hormones.
Thank you! I appreciate the explanation