Propagation of Hedera helix Cultivars Affected by Fertilizer Source, Harvest Conditions, Handling and Storage

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C.A. Conover, Ph.D., R.T. Poole, Ph.D. and K. Steinkamp*

University of Florida/IFAS
Central Florida Research and Education Center-Apopka
CFREC-Apopka Research Report RH-94-6

English Ivy (Hedera helix) is an attractive foliage plant produced in various sized standard containers and hanging baskets. English ivy is also used indoors in dish gardens, on trellises, as a ground cover in large indoor combination planters and wherever a trailing effect is desired. Numerous cultivars, differing in leaf shape, size, variegation and plant growth habit are available. Some growers maintain stock plants to supply their cutting needs while others purchase cutting material or harvest one or two cutting crops from ivy crops growing in 6-inch or larger containers before they are sold.

When cutting material is shipped, the standard shipping temperature is usually 60°F. Sometimes cuttings must be stored for a period of time before space becomes available on the propagation bench and since English ivy cultivars are among the more tolerant foliage plants, no visible damage has been observed on cuttings stored at lower temperatures. However, information is lacking on how storage may affect growth after propagation. The four experiments described here examined effects of stock plant fertilization, harvest date, maximum air temperatures in stock plant production areas, storage compared to immediate propagation and effects of various storage temperatures on selected cultivars of English ivy.

Materials and Methods

Experiment 1. Cultivar, Maximum Production Temperature and Fertilizer Source. Excellent quality 'Irish Gold' and 'Gold Dust' English ivy plants in 8-inch baskets, to be used as stock plants, were obtained from a local source on July 17, 1990. Plants had been grown from cuttings rooted 10 per 8-inch basket, using Metro Mix 500 potting medium (Scotts Co., 6656 Grant Way, Allentown, PA 18106). Stock plant baskets were maintained in greenhouses where maximum light intensity was 1500 ft-c. Plants were watered overhead as needed to maintain growth.

This was a 2 x 2 factorial experiment with 4 replications per treatment. Minimum air temperature during stock plant growth was 65°F while the fan-and-pad cooling system was set to restrict maximum air temperatures to 86 or 97°F. On July 19, 1990, baskets were topdressed with 10 g 19-6-12, or 13.6 g 14-14-14 Osmocote (Grace/Sierra Horticultural Products Co., 1001 Yosemite Dr., Milpitas, CA 95035) so that nitrogen rates were comparable.

On September 12, 1990, cuttings were harvested from stock plants and placed in 5-inch tubs filled with Metro Mix 500, 5 cuttings per pot. Cuttings were made from the mid-sections of vines and were about 3-in long. Cuttings were placed under mist until well rooted, then moved on October 16, 1990 to a greenhouse where air temperatures ranged from 65 to 90°F and maximum light intensity was 1500 ft-c. Plants were watered as needed. Containers were top dressed with 3 g/pot 19-6-12 on October 16, 1990. On January 3, 1991, plants were graded based on a scale of 1 = dead, 2 = poor quality, unsalable, 3 = fair quality, salable, 4 = good quality and 5 = excellent quality.

Experiment 2. Propagation Temperature. Excellent quality 'Ingrid Liz' and 'Starling' English ivy plants growing in 8-inch baskets were obtained locally on September 13, 1990. Baskets contained a commercially manufactured peat/bark growing medium top-dressed with 10 g 19-6-12 Osmocote/8-inch basket. On September 14, 1990, stock plant baskets were placed in greenhouse sections where maximum light intensity was 1500 ft-c. The fan-and-pad cooling system restricted maximum air temperature in greenhouse sections to 86 or 97°F. Baskets were watered four times per week.

Cuttings were periodically harvested from the mid-sections of vines from stock plants, as in experiment 1, and then graded based on a scale of 1 = dead, 2 = poor quality, 3 = fair, 4 = good and 5 = excellent quality. Cuttings were harvested and graded on September 14, October 9, October 16, October 23, October 30, November 6, November 13, November 20, November 27 and December 5, 1990.

Experiment 3. Storage Temperature and Duration. As in the preceding test, excellent quality 'Ingrid Liz' and 'Starling' English Ivy plants growing in 8-inch baskets were obtained locally on September 13, 1990 and used to obtain a crop of cuttings. For both cultivars used in this test, cuttings were propagated immediately or stored at 35, 40, 45, 50 or 60°F for 18 or 36 days. Four replications per treatment were made for each cultivar of English ivy tested.

The control group was propagated on September 13, immediately after harvest, on a greenhouse mist bench. Other cuttings were placed in plastic bags, then stored in coolers where air temperature was maintained at 35, 40, 45 or 50°F for 18 or 36 days and then propagated under mist.

All cuttings were rooted in 4-inch pots, 5 cuttings per pot, using Vergro Container Mix A (Verlite Co., Tampa FL 33610). On October 23, 1993, the control group was moved from the propagation area to a greenhouse where maximum light intensity was 1500 ft-c, air temperatures ranged from 65 to 90°F and plants were watered three times per week. Cuttings stored 18 days were removed from coolers, potted and placed on the mist bench on October 1, 1990. Cuttings stored 36 days were potted and placed under mist in the propagation area on October 18, 1990. The entire cutting crop, including the control group, was placed together on a greenhouse bench on November 14, 1990 and top-dressed with 3 g 19-6-12 Osmocote/4-inch pot. Maximum light intensity was 1500 ft-c, air temperatures ranged from 65 to 90°F and plants were watered three times per week.

Plants grown from cuttings were graded based on a scale of 1 = dead, 2 = poor quality, unsalable, 3 = fair quality, salable, 4 = good quality and 5 = excellent quality, on January 3, 1991. Plants propagated from cuttings in the control group which had not been stored were provided a longer growing period compared to plants propagated after 18 or 36 days in coolers.

Experiment 4. Storage Temperature. In this experiment, cuttings harvested from two cultivars were propagated immediately or stored at one of five temperatures before propagation. There were 5 replications per treatment for each cultivar tested. Single-eye node cuttings of 'Ingrid Liz' and 'Rolf' English ivy, from the mid-sections of vines, were obtained from local sources on October 17, 1990. Cuttings were propagated immediately or stored in coolers maintained at 35, 40, 45, 50 or 60°F for 28 days before propagation.

On November 15, 1990, cuttings were removed from coolers and propagated. All cuttings used in this experiment were propagated 5 per 5-inch tub, using a commercially manufactured potting medium. Mist was provided until cuttings were well rooted. Ivy were maintained in a greenhouse where maximum light intensity was about 1500 ft-c, air temperatures ranged from 65 to 90°F and plants were watered as needed. On January 3, 1991, plants grown from cuttings were graded, based on the same 1-5 scale described earlier.

RESULTS

Experiment 1. Cultivar, Maximum Production Temperature and Fertilizer Source. On January 3, 1991, plant grades of the 5-inch crop were not affected by the different maximum air temperatures stock plants had received, with 86°F producing the same quality as 97°F. Stock plant fertilizer source affected quality of 'Irish Gold' but not 'Gold Dust' (Table 1). The 5-inch 'Irish Gold' pot crop grown from stock plants getting 19-6-12 were much better than the crop grown from stock plants getting 14-14-14. Additional research on fertilization is planned in order to determine proper nitrogen (N) and potassium (K) ratios.

Experiment 2. Propagation Temperature. Although an overall reduction in cutting quality occurred between September and December, there was little effect from maximum temperature (Table 2). Maximum air temperature in stock plant growing areas only affected 'Starling' cuttings on November 20, when better quality cuttings were harvested from stock plants, maintained at the higher air temperature of 97°F, but this single instance may be due to chance. Decline in cutting quality over time may have been caused by naturally decreasing light levels and night temperatures occurring as fall progressed into winter.

Experiment 3. Storage Temperature and Duration. The two cultivars responded differently to treatments. Plant grade of 'Starling' was not affected by storage temperature or duration while best quality 'Ingrid Liz' plants were grown from the control group which was propagated immediately after harvest (Table 3). Plant grades for 'Ingrid Liz' decreased as storage duration increased and plants propagated from cuttings stored for 36 days were unsalable when plant grades were recorded on January 3, 1991.

Experiment 4. Storage Temperature. As in the preceding experiment, best quality 'Ingrid Liz' plants, were grown from cuttings in the control group (Table 4). Best quality 'Rolf' plants were also grown from the control group cuttings. However, quality of 'Rolf' plants grown from cuttings stored at 50 or 60°F (between fair and good) was better than quality of plants grown from cuttings stored at 45°F (just fair).

Conclusions

On first glance, the data provided in this report may seem confusing. However, on closer examination, some useful information relating to stock plants as well as the potential for storing cuttings of several different cultivars of English ivy can be seen.

More research needs to be conducted on fertilizer sources as the limited data presented here may be misleading. Temperature data from two experiments showed production of stock at maximum temperatures of 86 or 97°F had no real effect on cutting quality. This is contrary to popular opinion which is that English ivy needs as cool a temperature as possible during summer in Florida.

Storage experiments indicated excellent quality plants could be produced from 'Starling' cuttings without storage and also when cuttings had been stored at any of the temperatures tested. However, 'Rolf' stored fairly well only at 50 or 60°F and 'Ingrid Liz' did not store well at any temperature. These data suggest that storage potential is probably somewhat cultivar related. Therefore, additional research will be needed to determine optimum storage temperatures for the most widely grown cultivars.

Data generated from these experiments indicate the need for more research on English ivy stock plant maintenance and cutting storage and propagation for cultivars of major economic importance.

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* Professor of Environmental Horticulture and Center Director (retired 7/96), Professor of Plant Physiology, and Technical Assistant, respectively, Central Florida Research and Education Center, 2807 Binion Road, Apopka, FL 32703-8504.

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References

1. Conover, C.A. and R.T. Poole. 1990. Light and fertilizer recommendations for production of acclimatized potted foliage plants. Nursery Digest 24 (10):34-36, 58-59.
2. Henley, R.W., A.R. Chase and L.S. Osborne. 1991. English Ivy. Univ. of Fla., IFAS, CFREC-A Foliage Plant Research Note RH-91-15.

Table 1. Plant grades^z of 'Gold Dust' and 'Irish Gold' English ivy grown from cuttings from stock plants receiving different slow release fertilizers and grown in 86 or 97°F maximum air temperatures. Experiment 1.

^zPlant grades were based on a scale of 1 = dead, 2 = poor quality, unsalable, 3 = fair quality, salable, 4 = good quality and 5 = excellent quality.
^yns, *; Nonsignificant or significant at P = 0.05, respectively.
^xStock plants were fertilized with 10 g/8-inch basket 19-6-12 or 13 g/8-inch basket 14-14-14 Osmocote controlled release fertilizer on July 19, 1990.

Table 2. Maximum air temperature during stock plant production and resultant plant grade of two cultivars of English ivy cuttings. Stock plants were placed in maximum air temperature September 14, 1990. Experiment 2.

^zCuttings were graded on harvest dates as indicated based on a scale of 1 = dead, 2 = poor quality, 3 = fair quality, 4 = good quality and 5 = excellent quality.
^yns, *; Results nonsignificant or significant at P = 0.05, respectively.

Table 3. Effects of storage temperature and duration on plant grade^z of English ivy cultivars 'Ingrid Liz' and 'Starling'. Experiment 3.

^zPlants grown from cuttings were graded on January 3, 1991, based on a scale of 1 = dead, 2 = poor quality, unsalable, 3 = fair quality, salable, 4 = good quality and 5 = excellent quality.
^yns, **; Nonsignificant or significant at P = 0.01, respectively.

Table 4.Effects of cuttings storage temperature and grower on plant grade^z of 'Ingrid Liz' and 'Rolf' English ivy. Experiment 4.

^zPlants were graded based on a scale of 1 = dead, 2 = poor quality, unsalable, 3 = fair quality, salable, 4 = good quality and 5 = excellent quality.
^yCuttings were propagated immediately or stored for 28 days at 35, 40, 45, 50 or 60°F.
^xns, *, **; Nonsignificant, significant at P = 0.05 or significant at P = 0.01, respectively.