Estimating Plant Material Requirements Commercial Plant Production

 Every time plants move through the production steps at a nursery losses are incurred.

 For example:  Not every cutting stuck in propagation will root.  When rooted cuttings are removed from propagation and transplanted to small plant culture a small percentage of them will not survive.  When plants are transplanted from small plant culture to their final field spacing a small percentage of them will not survive.

 If your marketing plan says you need 5,000 units of a particular plant variety how many cuttings should you stick in Propagation?  5,100?  6,000?  10,000?

 It’s important for nurseries to keep accurate propagation and transplanting records.  A simple formula can allow you to calculate plant requirements; Required Quantity = Target Quantity ( 1 – estimated % loss) ( 1 – estimated % loss)

 For example: A nursery knows from it’s records that about 10% of the Spiraea ‘Goldflame’ it sticks as softwood cuttings will not root. The nursery has a target of 5,000 rooted cuttings. How many cuttings should they stick?

Target Quantity = 5,000 Estimated % loss = 10% =.1 Using the formula: Required Quantity = 5,000 (1 -.1) (1 -.1) Required Quantity = 5,000 = 5,556 (.9 ) (.9 ) Check: 5,556 – 10% = 5,000

An Example Showing Multiple Losses at Various Steps in Production

Estimating Propagation Requirements

 Cuttings in a propagation greenhouse are stuck at close spacings.  Some common spacings are:  2 x 2 inches  2 x 3 inches  3 x 3 inches  3 x 4 inches  etc…

 If a cutting is stuck at a 2 x 2 inch spacing, then that cutting consumes 4 square inches of “space”.  5,000 cuttings stuck at a 2 x 2 inch spacing would consume 20,000 square inches of space.  Since one square foot = 144 square inches, 20,000 square inches equals about 139 square feet.

 A nursery has 10,000 square feet of propagation space in their greenhouse. How many cuttings, stuck at a 2 x 3 inch spacing, will the propagator be able to fit into the propagation greenhouse?  Each cutting consumes 2 x 3 = 6 square inches of space.  10,000 square feet x 144 square inches/sq ft = 1,440,000 square inches of propagation space.  1,440,000 sq inches/ 6 sq inches = 240,000

The End