PROPAGATION HINTS
FOR CONIFERS
©

James A. Wick, Peach Grove Nursery, Tennessee, USA

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   First let me say that most nurseryman (and all true plants men) are generally willing to help one another out and I have no hesitation in asking fellow professionals for hints.   Such networking ends up being beneficial for everyone.   The only thing that I care to keep to myself is the suppliers of the plants I buy and the exact locations of some mutations, which I am the soul grower of. 

   I like you, am a very small nursery being the owner, manager, mechanic, and labor.   Last week I did my first interview for what may be my first ever employee.  I have a 16x16 cold house, which is used for propagation and over wintering of very select plants (for as mild as it is here most everything over winters outside). 

   My rooting technique is fairly simple and requires minimal infrastructure.  I use the cold callus technique.  Simply put, stick in the winter with no bottom heat.   Callus formation will take place and once media heats up in spring roots will emerge.

  • Media: for conifers I use brown sand.  I have also used baked clay in the past but sand is cheaper.  Peat and various soil mixes that others use I find holds too much water and have greater rot problems (especially on Junipers). When I root softwood cuttings of flowering deciduous shrubs I use a mix of 80% sand and 20% peat which may prove beneficial on some of the Arborvitae's as well.

  • Prepping of cuttings:  I like to take a cutting from an area where bark has just hardened off but not old wood.  On Junipers, Arborvitae and Chamaecyparis I try to make cut about a 1/4 below a small side branch.  I pull this small branch off with downward motion which exposes the cambium in the branch collar giving a good wound for callus. If I do not have such a branch to pull off I don’t end up with suitable wound and I will use thumb nail to produce 1 scar.

  • Hormone:  My general rate is 5000ppm IBA.  I use Quick Dip liquid and mix to dilute to have the ability to mix different concentrations if needed.  Some Junipers (egg J. horizontalis) I will use a 2500ppm;  the IBA can burn the tissue and prevent callus formation.  If I am ever in question I will refer to the propagation notes in Michael Dirr's Manual of Woody Plants.

  • Timing:   Winter for conifers.  There are some like Taxus, which naturally produce hormones, needed for rooting only after a hard freeze.  But the main reason is that is when I have time.  With the cold callus method I only have to keep the sand moist and not worry about misting. High winter humidity and a transparent poly - but not clear - helps prevent foliar desiccation.

  • Other helpful hints:  Take cuttings from either young plants of plants in the community, which are butchered by local landscapers (pruning keeps juvenile hormones).   I luck out with an Industrial Park about an hour away with a hedge of Juniperus x pfitzeriana 'blue and gold' which they keep pruned at 3' (O.91m).  Not only do I have access to such a rare plant but their improper pruning makes my rooting very successful.  I have only observed on Arborvitae that collecting from shaded location of plant such as north side gives better rooting.

Stripping of foliage will create more exposed cambium and greater callusing.

   Chamaecyparis obtusa still poses problems for me but I am getting better.  After talking with other nurserymen within the ACS the simple matter is Hinoki Cypress is difficult at best.  One recommended to check every few months and if there is no callus tissue formation to put fresh cut on and restick.

   I keep an eye on my trays of cuttings making sure to remove the ones which turn brown to prevent fungal problems. But other than that and watering I leave them alone till July or August (this year was little later because I fell behind) at which time I will pot up the takes into 4" (10cm) pots with a 90% composted pine bark / 10% composted manure media.

James A Wick, Peach Grove Nursery




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