See below for tables with results and photos.
INTRODUCTION
Mixed containers continue to be an important component in the total sales of ornamental products. For the past five years, the OFA Short Course and the Ohio State University (OSU) have organized an annual workshop dealing with this topic. Each year, attendance at the workshop was high and often was sold out. To achieve such success for so long testifies to the importance of this topic.
Also, for the past six years, we at OSU have been conducting Mixed Container Trials, evaluating the plants’ performance over the length of the season. In other words, while a newly prepared combination looks good, based on plant size, color, texture, etc., how does it behave over time? For example, do the designs deteriorate, improve, or stay the same? This evaluation represents a measure of the sustainability of the design (more about this below when we describe our evaluation methodology).
The sixth year of the Mixed Container Trial has provided more insight into the performance and durability of plants grown in large combination planters. Four companies participated last year. The combinations as a whole, plus individual plants in each combination, were evaluated on a monthly basis in July, August, and September by the trial’s director and manager. Consumer Preference evaluations were also conducted monthly by our team of Master Gardener volunteers.
Objectives
We established two objectives:
1) To evaluate over time the combination of plants (design) as a whole as well as each individual plant in the combination
2) To compare cultivars grown in mixed container plantings versus the same cultivars grown in single cultivar ('monoculture’) containers
GENERAL INFORMATION
Transplanting Dates: June 3rd, 2008.
Container Size: 12" diameter for Single Cultivar (Monocultures), 16" diameter for combination plantings.
Location: outdoor, full-sun location in secured gravel area just west of our Columbus departmental greenhouses.
Media: Metro-Mix 300.
Preventative drench: Plugs were treated with a Plantshield drench just prior to transplanting.
Replications: Up to 3 for monocultures (1 plant per pot) and 3 for combination plantings.
CULTURAL PRACTICES
Irrigation: Watered via drip irrigation system on a timer. Timer was adjusted according with size of plants and time of year.
Fertilization: 16” diameter mixed containers were given 120 grams (4.23 oz.) of Osmocote 16-9-12. The 12” diameter monoculture containers were given 90 grams (3.17 oz.) of Osmocote 16-9-12.
Pruning: The Pelargoniums in the Monoculture pots were periodically deadheaded. No pruning or deadheading was performed on any of the other combinations.
Weather Conditions: Following a very wet June, dry and sunny conditions persisted for most of the summer.
PEST AND DISEASE PROBLEMS
Pests: Two-Spotted Spider mites were a problem on Verbena. Japanese Beetles were an issue on Sunpatiens, but they quickly recovered.
Diseases: None serious.
Cultural Issues: Wind damage late in the season due to the remnants of a hurricane. Some more vigorous varieties tended to out-compete less vigorous varieties.
EVALUATIONS
The Consumer Preference Evaluations and the OSU Performance Evaluations were performed in July, August, and September. The Consumer Preference evaluated overall appearance and aesthetics of the containers on a personal preference basis.
The OSU Performance Evaluations evaluated the Balance/Dominance of the containers as a whole and the individual plants contribution to the design. Balance/Dominance is an index used to describe the dominance of a particular component of the mix (one plant may be ‘taking over’). In other words, balance/dominance is a measure of the sustainability of the mixed-container design. This index is not related to aesthetics: a very balanced combination may not look appealing and vice versa.
Evaluation Criteria: Ratings were based on a 1 - 5 scale:
1 = poor/not acceptable
2 = fair
3 = good
4 = very good
5 = excellent.
Design Codes for Mixed Containers:
Ball Designs: BL-1 – BL-5
Bodger Designs: B-1- B-5
Paul Ecke Ranch Designs: E11 – E-5
West Flower Designs: Carnival and Orient
RESULTS
Results tables and photos can be seen at the following URL:
http://floriculture.osu.edu
TOP COMBINATIONS IN MIXED CONTAINER TRIAL
The results in Table 1 are the average consumer preference ratings for the combinations for the months of July, August, and September. The best performing combinations with an overall season average in the range of 3.59 to 3.6 (on a 5 point scale) were: Ball-5, Ball-1, Bodger-5, Ecke-3, and Carnival.
The evaluations done by the Trials Director and Manager are presented in Table 2.
TOP CULTIVARS IN MONOCULTURE CONTAINERS
The monoculture pots were trialed separately to the mixed combinations. All the plants that were part of the mixed container designs were also separately trialed in 12” diameter monoculture containers and evaluated on the same dates as the combinations. Results of the monoculture evaluations are shown in Table 3 (by consumers) and Table 4 (by the tria manager and director).
- Best Monoculture Containers
The best performing monocultures with an overall season average in the range of 5.00 to 4.00 (on a 5 point scale):
Perilla Magilla Purple, Petunia Tiny Tunia Rose, Ornamental Millet Jester, Sedum makinoi Salsa Verde, Scaevola Summer Fan, Portulaca Rio Scarlet, Talinum Limon, Juncus Javelin, Begonia Solenia Red Improved, Coleus Trailing Plum, and Coleus Midnight Train.
Also performing well with ratings from 3.99 to 3.65:
Petunia Tiny Tunia Cabernet, Petunia Tiny Tunia Cranberry, Dichondra Silver Falls, Impatiens Sunpatiens Orange, Calibrachoa Celebration Indigo, Verbena Aztec Red Velvet, Begonia Solenia Dusky Pink, Petunia Tiny Tunia Blue, Purslane Hot Shot Rose, Ipomoea Sweet Caroline Bewitched, Calibrachoa Celebration Red, and Impatiens Sunpatiens Spreading Salmon w/ Variegated Leaf.
So, what did we learned in all these years of evaluating mixed containers? Esthetic appeal (color, contrast, shape, texture, etc.) is important. However, long-term performance should be considered when planning new designs.
Most combinations deteriorate over time. Nothing new with this finding! However, how fast do the designs tend to deteriorate? In other words how “sustainable” are the designs? Most designs tend to become unbalanced and the quality of some plants decreases. As a consequence, consumer preference also decreases. At best, some combinations maintain (“sustain”) quality while very few combinations improve over time.
Shade loving plants, like Impatiens, Lamium and some Coleus, benefit from shade provided by companion plants. Lamium is a prostrate, shade-loving perennial (although there are some cultivars that are sun tolerant) that benefits from the shade of any other plant in the combination, whether tall or not.
- Tip: Know the light requirements of the plants you are using for your mixed containers.
Slower-growing/less vigorous plants are poor competitors. Most of these thrive in cooler temps as well, so they tend to kick into gear towards the end of the season: Argyranthemum, Diascia, Lobelia, Nemesia, Leucanthemum, and Agastache.
- Tip: Choose carefully the companions for this type of plants!
Ipomeas are wonderful, vigorous plants for mixed containers but can over-compete some of their companion plants.
- Tip: Use these plants with caution.
It is important to know the growth habit of the plants used in combinations. Slow growing plants should be planted when they have achieved a substantial size (“grow and plant”) that will allow them to compete with the more vigorous species/cultivars. The use of PGR, e.g. dipping the root balls of vigorous liners in a mild PGR solution should be considered to slow (at least for some time) the growth of these plants and even the competition field.
- Tip: Know the growth habit of the plants you are using in your mixed containers.
Some crops, like petunias and calibrachoas, tend to show chlorosis symptoms. Although the problem is usually cultivar specific, it is important to treat these plants differently (e.g. using an acidic fertilizer). Unfortunately, some plants, like geraniums, do not like low pH and should not be planted next to acid loving plants.
- Tip: Know the pH requirements of the plants you are using in your mixed containers.
Some plants are very responsive to fertilizers, for example sweet potato vines and some coleus cultivars. At high fertility levels, they grow so much that they dominate the combinations. In some trial containers, the only visible plants were coleus or ipomoeas.
ACNOWLEDGEMENTS
We would like to acknowledge the following companies for participating in the trial:
Plant Sponsors:
Ball Horticulture, Bodger Botanicals, The Paul Ecke Ranch, and Westflowers
Supply Donors:
Dillen Products (Containers), Dramm Corporation (irrigation supplies), Sun Gro Horticulture (potting media), Bioworks (Plantshield), Buckeye Resources (mulch)
Thanks also for the excellent support from our staff members, David Snodgrass and Jim Vent, as well as our student worker, Misty Wright. Special thanks to our extremely talented and dedicated Annuals Team of Master Gardeners and Chadwick Volunteers for their container designs and their dedication throughout the season. Also, thank you to Ken Chamberlain for photographing the combination containers.
