Maintaining plant visual appearance in the retail environment is important for encouraging sales to the consumer. The amount of postharvest shrinkage and loss of saleable plant material in the retail environment varies by operation, but in one survey of several operations, it has been estimated to average 14 percent (Will Healy, Ball Horticultural Co., personal communication). Losses due to poor plant quality reduce profitability of wholesale and retail operations, especially in an era when producers must accept the losses for unsold plant material.
Due to the seasonal nature of spring bedding plant sales, outdoor weather conditions have a huge influence on consumer purchasing decisions. A weekend of poor weather means many plants must be held longer until they can be sold. Under these conditions, losses of plant quality include: leaf yellowing, premature leaf or flower drop, excessive elongation under low light conditions and the potential for extended insect and disease development.
Here are 10 tips spanning both production and retail that can enhance retail shelf life.
1. Don’t Build Buffer Time Into The Production Schedule
When scheduling your crops, it can be appealing to add an extra week or two to the production cycle, just in case something happens. Don’t give in to this temptation. Try to make your schedule as exact as possible so plants are in their prime when they are shipped.
Adding extra weeks as a buffer means you’ll end up with overgrown, stretched crops, which may be unmarketable to the consumer. This will make shipping them and caring for them at retail more difficult. Your best tool for accurate scheduling is detailed records from previous years. Once the crop is growing, monitor it periodically to be sure it is on track. If needed, you can adjust greenhouse conditions to push or hold back the crop.
2. Give Them Space
As the leaf canopy of a plant grows and begins to overlap with its neighbor, the plant’s shade-avoidance response is triggered. This leads to increased stem elongation and can result in excessively tall and fragile plants. When the plants are pulled for shipping, stems may break or become damaged later. Therefore, respacing containers is critical as plants grow out of their container dimensions.
If there is not enough greenhouse space or labor to respace containers, then it is critical to use cultural methods (high light, decreased water, fertilizer programs) or plant growth regulators (PGRs) to constrain plants from growing excessively large.
3. Provide Enough Light
The quantity of light plants receive, measured as daily light integral (DLI), directly influences plant growth and quality. High DLI promotes sturdy plants (thick stems) with increased branching and flower number. Light is often limiting during December to March production conditions. Supplemental light should be considered when crops are growing during these months in northern greenhouses.
Greenhouses typically shade 30 to 50 percent of sunlight, due to their glazing and overhead structural components. Growers can improve the amount of sunlight reaching plants by washing the greenhouse glazing, replacing aged polyethylene and avoiding shading from excessive hanging baskets.
Low light conditions contribute to taller plants with soft growth. High light helps build up a plant’s carbohydrate reserves, giving it more energy during low light conditions of shipping and retail. Minimum DLI requirements vary by plant species. An excellent article on the topic is available at bit.ly/measuringdailylightintegral.
4. PGR Me ASAP
As noted above, PGRs are an important tool to keep plant growth in check during production. PGRs can also be used near the end of production if plants are ready to ship, but must be held for extra weeks. Be careful not to overdo it. Nothing will annoy a consumer more than a plant that doesn’t grow out in their landscape. If needed, apply a low label rate as a spray, which usually has less residual activity (i.e., persistence) than a drench. Consider using daminozide- or chlormequat-based materials, as these have a shorter residual effect (typically seven to 10 days) compared with other PGRs.
5. Tone Plants By Decreasing Night Temperatures Before Shipping
Toning, or hardening plants near the end of the production cycle, is important to reduce damage during shipping and will help the plant last longer in retail. One strategy for toning is to acclimate the plant to drier conditions by watering less frequently. Allow the plant to dry slightly between watering, but don’t let the plant visibly wilt.
Another effective toning strategy is to expose plants to lower night temperatures during the final two to three weeks of production. Suggested temperatures vary according to plant sensitivity to cold. In general, keep night temperatures for cold-tolerant plants at 50°F to 55°F and at 55°F to 60°F for cold-intermediate plants. For cold-sensitive plants, keep night temperatures at 60°F to 65°F for toning (Table 1).
Table 1. Suggested Night Temperatures For Toning Bedding Plants
(50°F to 55°F)
(55°F to 60°F)
|Cold-Sensitive (60°F to 65°F)|
|Petunia (Bravo, Dreams, Easy Wave)||Geranium||Hibiscus|
6. Provide Moderate Light At Retail
Once plants make it to retail, low temperatures and moderate light will help extend plant quality. Low light levels and warm temperatures can lead to premature leaf and flower senescence. Avoid excess shading, such as holding plants on racks/shelves for an extended period. Lower tiers may have 80 to 90 percent less light than the upper tier. It also is best to avoid direct sunlight, as this can cause excessive temperatures during the middle of the day. Therefore, at retail 50 to 60 percent shade is ideal.
7. Water Judiciously At Retail
This one sounds easy enough, yet I’ve seen several retail operations where plants were not getting adequate water. High temperatures and crazy schedules for employees mean plants may not get the water they need. When you water, don’t just give plants a splash. Ideally, plants should be watered thoroughly each time, so you don’t need to rewater several times a day.
We conducted a trial at Cornell to determine how many days it took different bedding plant crops to wilt in a simulated retail environment. Plants were grown in 4-inch pots until they reached flowering. They were then kept in a greenhouse with 50 percent shade and 74°F average daily temperature. Lobelia, petunia and bacopa wilted after three days without water. Several plants including calibrachoa, garden impatiens, New Guinea impatiens, snapdragons and pansies wilted after four to five days. Fibrous begonias and zonal geraniums were retail rock stars; they didn’t wilt until 13 and 16 days without water, respectively.
8. Feed Me, Seymour!
Don’t let the retail establishment turn into the Little Shop of Horrors; continue to feed plants at retail. Common nutritional problems for plants held long at retail include nitrogen deficiency (yellowing of lower leaves), magnesium deficiency (yellowing between the veins of lower leaves) and iron deficiency (yellowing between the veins of upper leaves).
At retail, you are not trying to push vigorous plant growth, but rather maintain plants and keep them green. Therefore, constant liquid feed rates at retail can be decreased to about 50 ppm nitrogen with a complete fertilizer. If fertilizing once a week, target 250 to 300 ppm nitrogen with a complete fertilizer. If you don’t have a fertilizer injector, controlled release fertilizer (CRF) is another excellent tool. Growers should add CRF before shipping or retailers can add it when they receive plants. Customers will also be pleased with the several weeks of fertility provided by the CRF.
9. Don’t Stop Scouting
Good pest management practices don’t stop at retail. Start by inspecting plant material in a separate area when it arrives. Be sure to scout plants weekly for insects, diseases and nutritional problems. Record observations so you can track trends and take action as needed. Help prevent diseases by maintaining good air movement. Don’t let foliage stay wet overnight and remove spent flowers.
10. Don’t Be Afraid To Pull The Plug
Ideally, warm, sunny weekends will abound, and plants will fly off the shelves to consumers eager to garden. When plants are not moving out, the tips above will help them stay attractive longer.
Ultimately, a plant can only be held so long at retail before it becomes unmarketable. Knowing when to pull the plug and compost a plant is important. Poor quality plants can dissuade customers from purchasing. It hurts to throw plants away, but fresher plants will encourage more purchases.