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Finding the Right Growing Medium to Propagate Plant Cuttings

Thursday, February 23, 2023

Young plant production continues to be a growing segment of the horticulture industry. Over the last several years, many producers have moved from seed germination to cutting propagation. This has become popular for specialty varieties and branded plants.

While young plants are still produced with seed germination and plugs systems, the propagated and rooted cutting market has evolved into new processes with specialized equipment. Several companies have developed machinery to wrap paper and other materials around growing media to form small pots.

Characteristics of Paper-Wrapped Pots for Propagating Cuttings 

These miniature pots are available in assorted diameters, ranging from 15 mm up to 120 mm (5/8” – 4.75”). They represent an interesting practice for organic cultivation as some of these paper-wrapped pots are 100% bio-degradable. They are made by extruding the growing medium into a ‘tube-shaped’ outer wrapper and gluing the seam inside the wrapped tube. When the medium “tube” is filled, the paper-wrapped tube is cut into a specific length to form paper pots that are placed into individual cells within a growing tray.

The smaller size paper-wrapped pots (15-35 mm) are used mostly for cutting propagation. Larger sizes are used for the propagation of greenhouse foliage, woody ornamentals for nurseries, and ready-plant annuals for the landscape trade. There are different needs for growing media for each of these applications.

Rosemary cuttings rooted in 25 mm paper-wrapped cells. Source: Premier Tech

Machinery That Requires a Growing Medium Free of Sticks

With these types of pots, the growing medium must be free of sticks to avoid tearing the wrapping or damaging the saw blades that cut each pot. Clean product works better with automated machinery and there are fewer worries about bridging small cells with plug trays.

Most growers prefer a fibrous growing medium that has good air porosity. It is a challenge for peat moss producers to remove all sticks and small tree roots from Sphagnum peat moss because they are found naturally. The challenge is to screen out this debris while retaining the fiber of the peat moss to have a well-structured growing medium.

Screening Process

The industrial division of Premier Tech, Premier Tech Systems and Automation, has developed an improved screening system to process Canadian Sphagnum peat moss with minimal fine peat-moss particles that is virtually stick-free.

This innovative equipment and process of screening Sphagnum peat moss, along with a precise blend of coir (horticultural grade), perlite, limestone, wetting agent, soluble starter nutrient and active ingredients are used in formulating the PRO-MIX germination and young plant production growing media: PRO-MIX FPX and PRO-MIX FPO (for organic production).

Plug trays with PRO-MIX. Source: Premier Tech

PRO-MIX Growing Media Perfectly Suited for Cuttings

Here is why the PRO-MIX FPX and PRO-MIX FPO growing media work very well with cuttings including those in paper-wrapped pots:

PRO-MIX FPX

Ingredients

• 80-90% Fine Canadian Sphagnum Peat Moss – Short fiber
• Perlite – Plug Grade

Minor Components

• Calcitic and dolomitic limestone (pH adjuster)
• Wetting agent
• Starter fertilizer charge

Product Properties

Active Ingredient

PRO-MIX FPX is available with BIO-FUNGICIDE*, to accelerate seedling development and plant establishment, reduce the need for fungicide drenches and strengthen plant disease resistance. 

PRO-MIX FPO

Ingredients

• 60-70% Fine Canadian Sphagnum Peat Moss – Short fiber
• Coir – Horticultural Grade
• Perlite – Plug Grade

Minor Components

• Calcitic limestone (pH adjuster)
• Wetting agent
• Starter fertilizer charge

Product Properties

In summary, PRO-MIX FPX has been specially formulated for young ornamental plant production, and PRO-MIX FPO has been specially formulated for organic vegetable seed germination. Discover our products for young plant production here!

*PRO-MIX BIO-FUNGICIDE growing media products are only available in the US. In Canada, the PRO-MIX BIOSTIMULANT is available which can help root hair development on the roots and provide improved plant nutrient absorption. Check for the availability of products with your PRO-MIX sales representative.

For more information, contact your Premier Tech Grower Services Representative.

Ed Bloodnick Horticulture Director US-South East	JoAnn Peery Horticulture Specialist US-Central, Canada-Central	Lance Lawson Horticulture Specialist US-West, Canada-West
Troy Buechel Horticulture Specialist US-North East	Susan Parent Horticulture Specialist Canada-East, US-New England	Jose Chen Lopez Horticulture Specialist Mexico, Latin & South America