Propagating carnations in Rootcubes® / Horticubes® Growing Medium ensures successful and clean young plant production
Miriam Ndalila, Technical Consultant Africa, OASIS® Grower Solutions Africa, Nairobi, Kenya
John Kihia, Technical Manager Africa, OASIS® Grower Solutions Afria, Nairobi, Kenya
Vijay Rapaka, Ph.D., Manager, Corporate Grower, Research & Technical Support, Smithers-Oasis Company, Kent, OH USA
Carnations (Dianthus caryophyllus) are one of the most popular cut flowers sold worldwide. Dianthus, which is translated from Greek, means “Divine Flower.” The common name carnation is likely derived from “coronation,” as the Greeks used dianthus flowers in the crowns for the athletes. Carnations are commercially propagated using terminal cuttings harvested from the later shoots. Carnations are susceptible to several diseases during propagation and cultivation. The major carnation diseases that can cause most damage during propagation and at transplant stage are Rhizoctonia stem rot and Fusarium stem rot and both are caused by soil borne fungi. With Rhizoctonia stem rot, the symptom on rooted cuttings appears as a moist grayish-black rot at the soil line, which causes the plant to wilt and die. In the case of Fusarium stem rot, the symptoms on rooted cuttings can range from wilted cuttings with a severely reddish-brown crown rot to apparently healthy looking cuttings with small amber colored internal crown lesion. When the latter gets transplanted into sterilized media, it serves as an initial source of contamination. During cultivation, the major carnation diseases that can cause most damage are Fusarium wilt and Phialophora wilt. Again, these disease are caused by soil borne fungi. The key elements for successful carnation production besides starting with clean plant material include: clean propagation media and growing media and fungicide application on a regular basis.
Propagating carnations in OASIS® Rootcubes® / Horticubes® Growing Medium ensures successful and clean young plant production.
- The Rootcubes® and Horticubes® Media are uniquely engineered propagation media.
- The foam media is a thermoset material and is considered to be sterile because of the high temperature involved during the manufacturing process.
- Furthermore, it is formulated with optimal air / water ratio to promote fast and uniform rooting of vegetative cuttings.
- Horticubes® medium is relatively higher drainage and creates drier environment at the root zone compared to Rootcubes® medium. Depending on the crop / cultivar requirement and climatic conditions in the greenhouse, Rootcubes® or Horticubes® medium can be used for propagation of carnation cuttings.
Following are the general procedure for propagation of carnation cuttings in Rootcubes® Wedge® or Horticubes® Plugs:
- Start with clean shoot-tip cuttings harvested from a healthy stock plants.
- The cuttings cab be directly inserted into the propagation media for immediate rooting or can be cold stored for several weeks before rooting.
- Prepare the propagation area by placing the foam medium on the bench. Note: The Rootcubes® Wedge® comes in plastic strip or trays and the Horticubes® comes in a sheet format. Separate the cubes into individual plugs and populate into a tray.
- Thoroughly water the medium using complete nutrient solution using a fertilizer similar to 15 (N) -5 (P) -15 (K) and Cal-Mg] at a rate of 50 ppm N.. Complete saturation of the foam can be achieved by sub irrigation or overhead water. Note: With overhead watering, consider using a watering hose and a nozzle. It takes several passes to completely saturate the foam medium. Break open and inspect few plugs to ensure the foam is completely saturated or not. Note: Overhead misting is not sufficient enough to saturate the foam medium.
- Insert the cuttings ~25% of the height of the foam and space them 4 to 5 cm apart.
- Consider using a rooting hormone as it can help improve the uniformity in rooting with carnation cuttings.
- Misting: The frequency of misting depends on greenhouse conditions such as light intensity temperature, humidity, and also the air movement. Generally, mist for 6 seconds every 8 minutes. Reduce the misting frequency as the cuttings establish in the propagation environment. Never let the cuttings wilt and foam media to dry out excessively during the course of propagation.
- Fertilizer and watering: After 10 days into propagation, consider watering with a hose and a breaker every 2 to 3 days with complete nutrient solution using a fertilizer similar to 15 (N) -5 (P) -15 (K) and Cal-Mg] at a rate of 50 ppm N.
- Humidity and Air circulation: Maintain high humidity (90 – 100%) levels and reduce air circulation to avoid wilting of the cuttings.
- Light levels: Generally, carnation cuttings can handle higher light during propagation. Shade the propagation environment during afternoon hours.
- Temperature: Optimal rooting occurs when root zone temperatures are maintained (usually with bottom heating) between 78° and 83° F (26° to 28° C). The recommended daytime air temperatures are between 76° and 82° F (24° to 28° C) and nighttime air temperature are between 70° to 74° F (21° to 23° C).
- Rooting: Typically, it takes about 3 week for rooting carnation cuttings and after that they are ready for transplant.
Transplanting Rootcubes® Wedge® or Horticubes® Medium
Carnations are very prone to soil borne fungal diseases and nematodes. Therefore, it is recommended to transplant into fumigated or pasteurized media. Rootcubes® Wedge® or Horticubes® media can be transplanted into a container to be grown inside a greenhouse or in an outdoor location, as long as the growing media can be maintained moist with a drip or some other sort of irrigation system until the plants are established.
Note: Do not transplant directly into a field where media moisture cannot be controlled using an irrigation system.
Following are the general procedures:
- Fully saturate the Rootcubes® Wedge® or Horticubes® medium before transplant.
- Always transplant into a moist media. Note: Carnations perform well in inert media like volcanic rock.
- Note: Once transplanted, it is a natural phenomenon that water quickly moves out of the foam into the surrounding matrix as a result. Roots grow rapidly into the surrounding media.
- Note: Do not let the foam dry out excessively before or during the transplant process.
- Note: Transplanting into dry media can jeopardize the survival of the plant because foam can dry out excessively.
- Thoroughly water the media after transplant. When first transplanted, the rooted cuttings can wilt easily, so sprinkle water as required.
- Once established, just water as required. Note: Overwatering can delay the transplant performance because the root will not grow out of foam.
- Carnations are sensitive to being planted too deep. Cuttings should be planted so that foam surface is barely covered or flush to the growing media line.