2020 ASCFG Hardy Eucalyptus Trial Report

 
When gardeners in cold climates try to grow tropical plants, we call it zone envy. When cut flower growers do it, we call it entrepreneurial.

The spicy fragrance and wonderful silvery foliage of eucalyptus leads growers of all types to try to grow it, despite its renowned sensitivity to cold. The most common or widely known eucalyptus in the trade are probably ‘Silver Dollar’ (E. polyanthemos) with its large round leaves, and ‘Baby Blue’ (E. pulverulenta and other similar species), with bright bluish-gray leaves that encircle the stem. Unfortunately for northern growers, neither is reliably hardy in cold climates, and many in the North have resigned themselves to treating them as summer annuals or high tunnel crops. Native mainly to Australia, there are over 700 species of eucalyptus. Some come from the southern island of Tasmania, which has a climate similar to the Pacific Northwest, or from the Australian Alps, which are more aspirational than truly tall, but nevertheless have snow and temperatures occasionally down to the single digits (oF).  

With all this in mind, the ASCFG conducted a trial with Southern Eucs to test a few cultivars. This is the report on the second year of the trial. Of the four trialers who stuck with us from last year, only Mary Royal, from Elko, GA (Zone 8a) had plants from all five cultivars surviving. Here at NC State, Zone 7b, three of the five survived: ‘Angus’, ‘Big O’, and ‘Funky Monkey’, although we have to say that we did not have a particularly cold winter. Barbara Lamborne, Zone 7a, also had three survive: ‘Angus’, ‘Big O’, and ‘Funky Monkey’. The hardiest of the trials may well be ‘Funky Monkey’. It was the only one to survive for Jamie Rohda in Zone 5, Nebraska. She noted that the one plant that overwintered for her did not grow as robustly as the ones she planted in the spring so the cold weather may have had a long-term effect.
Eucalyptus nicholii "Angus'
Eucalyptus nicholii ‘Angus’ (left) Mary: She harvested 50 stems/plant and the stems were 30 inches long. She gave all 5s for the customer appreciation, ease of cultivation, and grow again ratings (1-5 scale, 5 best). She noted that all four plants survived, but one was stunted and she rarely harvested from it. Her comments: Love Angus! So different! My customers love this because of the light, airy nature of the limbs. Very useful for floral work. The plants were slightly damaged from a strong wind. We had to provide substantial staking. This was honestly my favorite and I would love to have more!

Barbara: My customers like this one and call it fern eucalyptus, but we found it did not produce very many stems and the vase life was about a week.

Nathan/John: Wonderful, easy-to-use filler foliage. The fragrance is distinctly eucalyptus but not as strong as some types. The plants are vigorous and doing well, with no loss during the winters. The plants already have substantial trunks at the end of their second growing season. We gave it all 5s for ratings. Due to COVID we were not able to harvest regularly, but estimated that we would have had 30-40 stems/plant at a length of 24-30 inches. In our postharvest trials the vase life of ‘Angus’ was 7 to 8 days. Stems with toned growth lasted longer compared to fresh, bendable stems.
Eucalyptus neglecta ‘Big O’ (right) Mary: She harvested 30 stems/plant at 36 inches each. She gave all 5s for customer appreciation, ease of cultivation, and grow again ratings, and all plants survived. She noted that it is best to be sure stems are hardened before harvesting, and that they dried well. Her comments: Great for large arrangements. Really like how the longest branches have started to make a huge fan shape. Love this! Have not sold any of the fans yet. Too large for some floral arrangements. I really liked this cultivar. I have used it constantly. It is very dependable and probably the best producer.

Barbara: I love the look of this next one, but it did not produce many usable stems. Vase life was 2 weeks for what few we had to even trial. I find it interesting that this is one of the forms my old ‘Silver Drop’ plants in a tunnel are reverting to. In the tunnel they barely get sturdy enough to hold up.

Nathan/John: Long, substantial stems with a classic eucalyptus look. This cultivar has a beautiful distinct blue-gray coloration.  Plants reliably branched and produced multiple new shoots when harvested. Strong stems were easy to use. All four plants overwintered but one died suddenly during the summer, likely due to root rot. Due to COVID we were not able to harvest regularly, but estimated that we would have had 15-20 stems/plant at a length of 30-36 inches. We gave it a 4 for customer appreciation, 5 for ease of cultivation, and 3 for grow again ratings. In our postharvest trials the vase life was 8 to 9 days.
Eucalyptus neglecta 'Big O'

Eucalyptus rubida ‘Cab Sav’.  Mary: She harvested 15 stems/plant that were an average of 11 inches long. All plants survived.  She gave it a 5 for customer appreciation, 5 for ease of cultivation, and 3 for grow again ratings. Comments:  the color and size of the leaves makes this a very desirable cultivar. A favorite of customers. It just did not grow very big. I harvested some stems in the early summer, but it did not grow very much more. I completely stopped harvesting. I had lost 3 of the 4 plants when they arrived, so I only had 1 remaining plant. I would love to try the cultivar again.

'Eucalyptus parvula 'Funky Monkey'
Eucalyptus parvula ‘Funky Monkey’ (left) Mary: She harvested 25 stems/plant that averaged 25 inches long. All plants survived.  She gave it a 5 for customer appreciation, 5 for ease of cultivation, and 4 for grow again ratings. Comments:  Love the very small leaves and the branching. Excellent for floral work, but not useful for weddings. Florists don’t really like it, but regular customers do. It did not grow as large as ‘Angus’ or ‘Big O’, but we still cut many branches. I stopped cutting for a while, so it could grow more.

Barbara: ‘Funky Monkey’ was the best in terms of usable stems per plant and vase life.  It holds up for 3 weeks. The form is a nice alternative to the ‘Silver Drop’.

Nathan/John:  More compact than ‘Angus’ and ‘Big O’. Three of the four plants had a slow growth rate and were not as productive. The foliage was typically eucalyptus shaped, but smaller and easier to use than ‘Big O’. Stems were usually reddish when exposed to the sun. We estimated similar production to that of Mary: 20-25 stems/plant at a length of 20-24 inches. We gave it a 4 for customer appreciation, 4 for ease of cultivation, and 4 for grow again ratings. In our postharvest trials it had the longest vase life at 9 to 10 days.

Eucalyptus stelluta ‘Sheila’.  Mary Royal reported that only one plant out of four is remaining and it is less than 2 feet tall with very few stems. She has not harvested anything from it. Comments: Last year the leaves had spots and the plants did not grow well. In June three of the 4 plants died within about 2 weeks’ time. Not a viable choice for her zone.

Summary from last year.  For comparison, ‘Funky Monkey’ was the overall favorite due to its small green leaves on reddish stems. Trialers were already getting an average of 5.3 stems per plant that averaged 13 inches long, with responses ranging from 9 to 20 inches. ‘Cab Sav’ produced 4 stems/plant that ranged from 10 to 15 inches long.  ‘Big O’ was the fastest-growing cultivar with the longest stem length, 14.5 inches, and an average of 4.5 stems/plant. With ‘Angus’ trialers harvested an average of 3.9 stems/plant that ranged in length from 10 to 18 inches. Even last year ‘Sheila’ was the least favorite; trialers reported harvesting about 2 stems/plant that were 10 to 13 inches long.

Acknowledgments:  Thank  you to the four evaluators who returned their trial reports; we appreciate your time We especially thank Mary Royal,  the first to return hers. Thanks to Southern Eucs for providing plant materials.   All photos by John Dole.
 
Participating Company
SouthernEucs
southerneucs.com
 
Participating Trialers
 
Nathan Jahnke/John Dole
NC State University 
Raleigh, NC  
Zone 7b
Barbara Lamborne
Greenstone Fields
Purcellville, VA
Zone 7a
 
Mary Royal
The Royal Gardens
Elko, GA
Zone 8a
Jamie Rohda
Harvest Home
Waverly, NE
Zone 5