More Shrubs That Can Be Greenhouse Forced

More Shrubs That Can Be Greenhouse Forced

In the last installment, I sorted many common shrubs into “ease of forcing” groups, based on characteristics such as their visual impact in a container and disease problems.

Group 1: Would not fit into a mixed container program for the spring, including those with no outstanding features to their foliage or susceptible to disease. Since flowers were only formed on next year’s growth, forcing for flowers was out of the question.

Group 2: Will work for a spring program, but with numerous problems such as poor form, inconsistency of growth or flowering or unstable variegation.

Group 3: These plants work in the greenhouse, but require a bit more time, more marketing, etc.

Group 4: Plants that are easily forced and catch the eye. This group proved to be the most uniform, most colorful and most appealing to the eye of the consumer.

We determined the need, if any, for cold for all the shrubs brought into the program and sensitivity, if any, to photoperiod for many of them. Rooted liners in 32 tray packs were subjected to 33ËšF to 37ËšF in coolers for zero, four, six, eight or 10 weeks. Photoperiod treatments (long days or short days) were provided after the plants were removed from the cooler, planted in gallon containers and placed on the bench. The research was conducted on many taxa over a period of three years. No growth regulators were applied.

Here are a few others that fit in Group 4. Due to funding limitations, we did not look at them as closely as other subjects.

1. Buddleia ‘Peacock’: One of the better butterfly bushes we trialed.

z 34ËšF-37ËšF
y values followed by the same letter are not significantly different at p=0.05

Comments: Cold not necessary, this is one of the few shrubs that flower sufficiently on the bench. A short duration of cold reduced the bench time.

Recommendation: Receive plants in November, cool for six weeks. Plant in final containers and place on bench.

Results: A marketable plant will finish in 11 weeks in a gallon container.

2. Abelia ‘Silver Anniversary’: An excellent variegated shrub for the South. The variegation is appealing and stable.
z 34ËšF-37ËšF
y values followed by the same letter are not significantly different at p=0.05

Comments: Do not cool more than 6 weeks, and if long crop time is acceptable, do not cool at all. Cooling results in rapid death.

Recommendation: Receive cuttings in early November, transplant to final containers and place on bench.
Result: A marketable plant approximately four to five months after planting in a 1-gallon container.

3. Kolkwitzia ‘Dream Catcher’: One of our favorite shrubs, producing pendulous stems of coppery gold leaves. Very cold hardy.
z 34ËšF-37ËšF
y values followed by the same letter are not significantly different at p=0.05

Comments: Plants require cold or LD (data not shown). If provided with LD, little cold is needed. However if LD are not possible, cold is required

Recommendations: Receive cuttings in November, place in cooler for six weeks and then provide LD (night break lighting) in the greenhouse, or leave in cooler for eight weeks if plants are to be grown under natural winter days.

Results: A marketable plant in 12 weeks in a gallon container.

In summary, there are dozens of shrubs that can be grown in the greenhouse. There are many problems; probably the most limiting is the lack of a consistent supply of uniform cuttings. This is where the research efforts should be concentrated in the future.

 These articles demonstrably show that forcing shrubs can be accomplished in a reasonable amount of time. The selection is important, as we have also shown that not all plants lend themselves to these practices. I have no doubt the retail market is ready for more shrubs than ever before. With a proper marketing program, good signage and a consistent product, I see shrubs as the next perennials. After all, they are simply “perennials with bark.”

Leave a Reply

More From Varieties...
Asclepias tuberosa

April 29, 2017

Greenhouse Growing Tips for Asclepias tuberosa

Madeline Maynor, Growing Operations Manager for Landenberg, PA-based North Creek Nurseries, shares greenhouse growing tips for Asclepias tuberosa, the 2017 Perennial Plant of the Year.

Read More
Andropogon gerardii Blackhawks (Intrinsic Perennial Gardens)

April 25, 2017

Kelly Norris: Diversity is the Key to Growing the Ornamental Grass Market

Offering a selection of ornamental grasses that cater to customer needs will keep sales from stagnating.

Read More

April 25, 2017

41 New Vegetative Petunias From California Spring Trials 2017: Northern Sites

With the abundance of new introductions for the 2018 retail season, we’ve made it easier for you to sift through them by separating out the vegetative petunias from the Northern sites, which includes selections from Westhoff Flowers, Sakata Ornamentals, Danziger, Proven Winners, and Syngenta flowers.

Read More
Latest Stories
Asclepias tuberosa

April 29, 2017

Greenhouse Growing Tips for Asclepias tuberosa

Madeline Maynor, Growing Operations Manager for Landenberg, PA-based North Creek Nurseries, shares greenhouse growing tips for Asclepias tuberosa, the 2017 Perennial Plant of the Year.

Read More
Andropogon gerardii Blackhawks (Intrinsic Perennial Gardens)

April 25, 2017

Kelly Norris: Diversity is the Key to Growing the Ornam…

Offering a selection of ornamental grasses that cater to customer needs will keep sales from stagnating.

Read More

April 25, 2017

41 New Vegetative Petunias From California Spring Trial…

With the abundance of new introductions for the 2018 retail season, we’ve made it easier for you to sift through them by separating out the vegetative petunias from the Northern sites, which includes selections from Westhoff Flowers, Sakata Ornamentals, Danziger, Proven Winners, and Syngenta flowers.

Read More
Begonia Spectre Silver Terra Nova Nurseries

April 20, 2017

Terra Nova Nurseries Releases Two New, Attractive Begon…

Stardust is the latest addition to Terra Nova Nurseries’ existing T Rex Begonia series, and Silver is the first introduction to the company’s new Spectre Begonia series.

Read More

April 18, 2017

Cool Combos From CAST 2017 – Editor’s Choic…

With container gardening becoming more of a lifestyle among consumers than a trend, and breeders continuing to put more effort in container mixes and components, I feel I would be remiss if I didn't share some of the special combinations that not only caught my eye at California Spring Trials, but absolutely took my breath away and made me want to immediately get started gardening.

Read More
Danziger New Hires

April 16, 2017

Danziger Invests in Continued North American Business G…

As part of a new business structure for its North American market, Mike Fernandez has been appointed Market Manager North America for Bedding Plants and Perennials, and Kate Zvara was named as Key Account Manager and Retail Specialist.

Read More
Florida Flower Trials

April 12, 2017

Looking for Info on New Varieties for Hot Climates? Che…

The Florida Nursery Growers and Landscape Association’s Florida Flower Trials, which are focused on new and improved varieties able to thrive in the extremes of Florida’s climate, are a great opportunity to connect with national breeders.

Read More
Lupinus Staircase Series (Green Fuse Botanicals)

April 11, 2017

Begonias, Celosias Among Dr. Allan Armitage’s Favorites…

Check out some of Allan’s top picks from his final day at CAST 2017, which included visits to Green Fuse Botanicals and Floranova.

Read More
Rex Begonia container mix at Green Fuse Botanicals

April 11, 2017

Green Fuse Botanicals’ Rex Begonias and First Looks; Fl…

Here are the highlights from Green Fuse Botanicals and Floranova on the last day of CAST 2017.

Read More

April 7, 2017

Hort Couture Wows With Farm to Table; Florist Holland R…

On the last day for GroLink and the second to last for the Greenhouse Grower team, the wealth of genetics, marketing programs, and announcements were pleasing to our eyes, ears, and hearts.

Read More

April 7, 2017

California Spring Trials Day Five: Notable New Plant Va…

See some of the new varieties for 2018 displayed at Ball Horticultural and GroLink Plant Company on day five of California Spring Trials 2017.

Read More

April 7, 2017

PanAmerican Promotes Pentas, Plug-and-Play, and Veggies…

On Day 5 of the California Spring Trials, the Greenhouse Grower team hit the Southern California Trials and saw a multitude of new introductions and exciting programs.

Read More

April 7, 2017

CAST 2017: Musings of a California Spring Trials Rookie…

The number of opportunities presented to me are enough to make me rethink my location, but I still have a lot of big decisions to make for the future.

Read More

April 6, 2017

Dr. Allan Armitage’s Top Picks From Ball and GroL…

Here are Dr. Allan Armitage’s five variety picks, plus one display, from on Day 5 of CAST 2017.

Read More

April 6, 2017

Dümmen Orange Provides Retail Concepts; Terra Nova Offe…

Greenhouse Grower hit the Central Coast of California on our Day 4 of California Spring Trials, and what we saw was inspiring and exciting.

Read More

April 5, 2017

California Spring Trials Day Four: New Plant Intros fro…

The Greenhouse Grower team saw loads of memorable plants during day four, as it visited Dümmen Orange, Chisan Orchids, and Windmill Nursery. Dümmen had several notable introductions, including Wild Romance New Guinea impatiens in Blush Pink and White, which inspired the theme of its displays. One of the standout displays was its perennial combos with some new leucanthemum additions. Chisan Orchids in Los Alamos, CA, with Israeli breeders Hishtil, Jaldety, and Cohen Propagators, was a new stop on the route this year. Hishtil has a new gaura series out that includes a compact, low-growing variety, ‘Baby,’ with a mass of pink blooms. Cohen displayed Verbena ‘Mickey Red Rose,’ a unique bi-color that looks like a mixed combo, and Jaldety featured an interesting Cyperus prolifera. Windmill Nursery was the last stop of the day, with breeders Terra Nova Nurseries, Kientzler, J. Berry Nursery, and KiwiFlora. Terra Nova had several new heuchera for show, including ‘Onyx,’ which is a mounding, […]

Read More

April 5, 2017

CAST 2017: Musings of a California Spring Trials Rookie…

Set-aside all the varieties - I have come to the realization that being a grower is where I belong.

Read More

April 5, 2017

Dr. A’s Day Four Top Varieties for CAST 2017

Check out Dr. Allan Armitage's top five picks from visits to Dummen Orange, Chisan Orchids, and Windmill Nursery during day four of California Spring Trials 2017.

Read More