Click on the link to print or save this document: CROP SCHEDULING
2013 POINSETTIA SCHEDULING
Proper scheduling is the first step in producing high quality blooming poinsettias that reach the desired height and flowering dates. Using the forms provided, each product should be ‘scheduled’ as part of the planning process before cuttings are ordered and arrive at the greenhouse.
Product Specifications: Before developing a production schedule, define the product specifications. Answer the following:
1. When do the plants need to be ready for sale?
2. What pot size(s) will the crop be grown and sold in?
3. How many plants per container are required?
4. How tall do these poinsettias need to be?
5. How many branches and bracts are required at time of sale?
These are all questions that need answering before developing the schedule.
Market Date: Define the date(s) on which poinsettias should be ready for sale. Choosing varieties that naturally mature close to desired sale dates ensure that plants are not over mature or immature when brought to market. Proper variety selection can also reduce extra production related costs associated with manipulating timing such as lighting, black clothing, or with temperatures. Refer to Table 1 for natural finish dates in a central location.
Cultivar: Factor in the growth habit, flower initiation date, and flowering response of each cultivar. These characteristics influence the amount of vegetative growth needed to achieve the desired finished height. The flowering response time also defines how early or late plants will be ready to sell. Manipulation of the day length may be required, or a change in cultivars made to hit the market date. Table 1 identifies these characteristics of poinsettias offered by the Paul Ecke Ranch.
Flower Initiation Date: Flower initiation dates may vary slightly based on geographic location, light levels, temperatures, and plant stress. Use the table below as guide. Note that cultivars that initiate early should be planted and pinched early also to reflect earlier bud set and insure adequate time for vegetative growth to achieve desired height specifications. Varieties that are naturally tall should be pinched closer to flower initiation to reduce finished height.
Photoperiod Manipulation Requirements: If the desired cultivar’s natural finish date based on flower initiation date and response time do not match with desired finish dates then photoperiod manipulation must be used. To force earlier finish black clothing must be used to initiate flowers early. Determine black cloth start time by subtracting response in weeks from the desired finish date.
14 hour nights should be provided using black cloth. For later finishing lighting to extend the day length should be used to delay flower initiation. Day length extension lighting or night interruption lighting from 10 pm to 2 am can be used. Provide 10 f.c. of light at plant height. Begin lightin
September 5th. Calculate lights out date by subtracting response time in weeks from desired sale date. It is not recommended to light any variety past October 10th.
Vegetative Growth Requirements: Calculate vegetative growth requirements based on the finished height and flower initiation dates. In order to calculate vegetative growth requirements the grower must be aware of when a cultivar initiates flowers so that pinching can be scheduled accordingly. A properly scheduled pinch assures plants will have enough time between pinch and flower initiation to form enough leaves to achieve the desired finished height. Reduced time between pinch and flower initiation will result in shorter plants. The best example of this is the difference in the amount of time needed to achieve desired size between plants in 4” containers versus plants in 6 or 6.5” containers. In most cases pinching plants in 4” containers 5-7 days before flower initiation will still allow for adequate vegetative growth that results in an appropriate proportion of plant size to pot. If plants in 6 or 6.5” containers are pinched 5-7 days before flower initiation the result will be plants that are too short for that container size. Too much time between pinch and flower initiation will result in plants
that are too tall. The time needed for vegetative growth is based on two key factors; geographic location and vigor of each cultivar. Each cultivar has a different natural growth potential so more or less time between pinch and flower initiation is required based on natural vigor. Geographic location is also important because naturally higher light and warmer temperatures will result in more vegetative growth. Growers in southern climates will find that less time is necessary between pinch and flower initiation to achieve adequate size while growers in northern climates will find that more time is required. The charts provided (Table 2) suggest the production time for various forms based on location. Next, adjust the vegetative growth time based on height of the cultivar, see Table 3. If a poinsettia is listed as “short” in Table 1, additional time will be required to compensate. If a cultivar is
listed as “tall”, no additional time is added to the schedule. Once the location and cultivar vigor factors have been calculated, the sum represents the time required from pinch to flower initiation.
Pinch Date: The pinch date is determined by subtracting the vegetative growth requirements from the date of flower initiation. For non-pinched forms, go directly to the transplant date below.
Transplant Date/Establishing Time Prior to Pinch: Before pinching poinsettias, it is advisable to have adequate root systems established. The size of growing container and volume of media influence how long it takes for rooted cuttings to develop adequate roots prior to pinching. Small pots with less soil volume take the least amount of time for root establishment, while large pots with more soil (and greater moisture holding capacity) will take longer. Table 4 suggests the number of days typically needed to develop adequate root systems prior to pinching. As a general guideline, plants are established when they no longer wilt or droop from the shock of transplanting, even during the
warmest part of the day. Roots should be visible to the side and bottom of the pot. Using the values in Table 4, subtract the number of days from the pinch date to determine the optimum transplant date. It is important that the root systems are adequate and plants are established prior to pinching. If plants are pinched without adequate establishing the result may be poor branching and weaker, uneven growth.
Propagation Date: For cuttings that are rooted and transplanted as liners 4 weeks should be added to the schedule for time in propagation. Direct sticking in the final finished container may also be considered. If unrooted or callused cuttings are stuck directly in the finial finished container it generally takes 5 weeks from sticking until plants are ready for pinching.
Table 1 Growing Guidelines
Table 2: Vegetative Growth Requirements based on geographic location
Table 3: Vegetative growth adjustments based on vigor
Table 4: Establishing requirements for various sizes
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