Grouping crops can save you money - Michigan State …

1 Reprinted with permission from GMPRO. By Ryan Warner By Grouping crops according to certain variables, you can increase production efficiency and reduce the number of problems encountered. Grouping crops can save you money ONE OF THE GREAT CHALLENGES may actually increase total fuel costs that greenhouse growers face is the Impact of temperature for producing that crop. You are better incredible diversity of crops pro- on days to flower off growing these crops warmer so duced in a single operation. Each they are in the greenhouse for a crop may have its own optimal set of 62 F 68 F shorter period. environmental conditions (tempera- ture, photoperiod or nutritional Photoperiod effects requirements). Even though you may The light environment also has not be able to provide the optimal a huge impact on crop timing. environment for each crop, you can create a few separate environments. By appropriately Grouping crops , you General growing can increase production efficiency temperatures and reduce the number of problems.

2 Low-temperature plants When deciding which crops 58 days 45 days (60 F to 68 F). should be grown together, your first Abutilon, ageratum, ajuga, alstroemeria, priority should be to consider the alyssum, anemone, aquilegia, argyranthemum, factors that determine crop timing. bidens, bellis, brachyscome, bracteantha, The two biggest factors determining browallia, calibrachoa, centaurea, cyclamen, crop timing are temperature and dianthus, diascia, echinacea, flowering kale, light environment, most importantly 36 days 32 days foxglove , gazania, geranium (ivy), geranium photoperiod. (seed), heuchera, lamiastrum, lamium, lobelia Growing temperatures impact days to flower for Salvia farinacea Strata' (top) and (annual), marigold (all types), matthiola Temperature effects pansy Delta Pure White' (bottom). (stock), nasturtium, nemesia, oenothera, The rate of development of a osteospermum, oxalis, pansy, penstemon, plant (the leaf unfolding rate) is a temperature, reducing temperatures petunia (upright), phlox, sanvitalia, function of temperature.

3 As temper- increases production time of all schizanthus, snapdragon, viola atures increase, the leaf unfolding crops . However, some crops will be High-temperature plants rate increases. If the temperature more severely delayed than others. (68 F to 75 F). exceeds the maximum temperature, Reducing temperatures from 68 F Angelonia, anisodontea, begonia (fibrous), plants experience stress and leaf to 62 F increased time to flower of begonia (tuberous), celosia, cleome, coleus, unfolding rate declines. Salvia farinacea by 13 days. This same colocasia, cosmos, Cuphea rosea, dracena Given the high costs of fuel, many temperature drop only increased (spikes), fuchsia, gerbera, gomphrena, growers are tempted to reduce the days to flower of pansy by four days. gypsophila, helianthus, helichrysum, greenhouse temperature to save For crops that are severely heliotrope, hibiscus, impatiens, ipomoea, money on fuel.

4 Because the rate of delayed by lower temperatures, lantana, lavender, millet, nicotiana, New crop development is dependent on reducing the growing temperature Guinea impatiens, pentas, petunia (spreading), perilla, pepper, ornamental pepper, plectranthus, portulaca, salvia, scaevola, scoparia, scutellaria, stobilanthes, sutera (bacopa), tomato, torenia, verbena, vinca, vinca vine 74 GMPRO June 2007. Reefer Goes Here Page XX Reefer Goes Here Page XX. Photoperiodic night that a plant measures, long- classification day plants can be induced to flower of annuals by turning lights on for four or more hours in the middle of the night Obligate long-day plants (known as night-interruption or Ammi, asperula, callistephus, catananche, mum lighting), traditionally from centaurea, dill, fuchsia, gazania, ipomopsis, 10 to 2 Plants need to be lathyrus, lavatera, legousia, leptosiphon, exposed to approximately 2 micro- limnanthes, linum, lobelia, mimulus, moles per square meter per second nigella, nierembergia, oenothera, petunia, (about 10 footcandles) for night- platystemon, strawflower interruption lighting to be effective.

5 Within the long-day and short- Facultative long-day plants day plant classification, crops can be Ageratum, basil, calendula, further categorized as having an collinsia, dianthus, dimorphothica, obligate or facultative photoperiod linaria, pansy, petunia (grandiflora), response. Plants with an obligate phacelia, reseda, salvia, snapdragon, photoperiod response must be statice, sunflower, tithonia grown under that photoperiod for Obligate short-day plants flowering to occur. Plants with a Mina vine, hyacinth bean, African marigold facultative photoperiod response Request 31 . will eventually flower under any Facultative short-day plants photoperiod, but will flower much Celosia, cosmos, gomphrena, earlier if produced under the ipomea, morning glory, sanvitalia, appropriate photoperiod. signet marigold, zinnia Day-neutral plants Nutrition effects Amaranthus, carpanthea, centranthus, After crops are grouped based on cleome, cobea, nemophila, oxypetalum, the environmental variables, you can stock, verbascum create subgroups based on general nutrition requirements that are measured by electrical conductivity Many bedding plants are photope- and growing medium pH.

6 Riodic, meaning that flowering is Electrical conductivity (EC). To induced by a particular photoperi- maintain different nutrition levels od or daylength. between plant groupings, you can Long-day plants flower when the either have multiple fertilizer injectors daylength exceeds a certain critical set up to deliver different feed rates length (and the night is less than a or alternate between fertilizer and critical length). Plants need clear water for crops with lower daylengths of 14-16 hours (night nutrition requirements. Check your lengths less than eight to 10 hours) fertilizer injector regularly. Many EC. to flower. problems are simply due to clogged Short-day plants flower when or malfunctioning fertilizer injectors. the daylength is less than a certain Growing medium pH. Growing critical length (and the night length medium pH determines whether or exceeds some critical length).

7 Gener- not nutrients in the medium are ally, crops need photoperiods of available for plant uptake. Nutrients 11 hours or less (night length greater must be in solution to be taken up by than 13 hours) to flower. the roots; different nutrients are only Day-neutral plants do not flower soluble over a particular pH range. in response to daylength. Precautions. While each plant may Because it is the length of the have slightly different nutritional Request 32 . June 2007 GMPRO 75. Relative nutrient requirements of greenhouse crops Light electrical conductivity (1:2 dilution of to mS/cm). (SME of to mS/cm). (PourThru of to mS/cm). Aconitum, African violet, ageratum, anemone, anigozanthus, asclepias, aster, astilbe, balsam, begonia (fibrous, hiemalis, rex and tuberous), bracteantha, caladium, calceolaria, calla lily, celosia, cineraria, coleus, cosmos, cyclamen, freesia, geranium (seed), gerbera, gloxinia, impatiens, marigold, New Guinea impatiens, orchids, pansy, plugs, primula, salvia, streptocarpus, snapdragon, zinnia Medium electrical conductivity (1:2 dilution of to ).

8 (SME of to mS/cm). (PourThru of to mS/cm). Angelonia, alstroemeria, alyssum, Request 78 . arygeranthemum, bidens, brachyscome, bougainvillea, calendula, calibrachoa, carnation, centaurea, cleome, clerodendrum, coleus, crossandra, dahlia, delphinium, dianthus, diascia, dusty Miller, exacum, fuchsia, geranium (vegetative), helichrysum, hibiscus, hydrangea, ipomoea, Jerusalem cherry, kalanchoe, lantana, lily, lobelia, morning glory, nemesia, ornamental kale, ornamental pepper, osteospermum, oxalis, petunia, phlox, platycodon, ranunculus, rose, sanvitalia, scaevola, schizanthus, sunflower, sutera (bacopa), torenia, verbena, vinca vine Source: Adapted and expanded from PourThru Nutritional Monitoring Manual by Brian Whipker, William Fonteno, Todd Cavins and Doug Bailey, 3rd edition, 2000. Published by North Carolina State University. needs, most nutritional problems are simply due to poor EC or medium pH management.

9 Purchasing a pH/electrical conductivity meter is one of the wisest investments you can make. Regular soil testing and using graphical tracking to monitor pH and EC levels can avoid nutritional problems before they occur. Ryan Warner is assistant professor, Michigan State University, Department of Horticulture, (517). 355-5191, Ext. 1344; Request 79 . 76 GMPRO June 2007.