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Propagating Thuja Green Giant Arborvitae

Posted by Milly55 8 (My Page) on
Thu, Sep 22, 05 at 0:52

Hello, I have a rather long question - if you wouldn't mind taking a look and letting me know what you think...

I am new to propagation and on Sunday Sept 18th I made my first attempt. I chose Thuja Green Giant Arborvitae as I have heard Arborvitae are quite easy to root.

I cut stems 4"-10" in length, placed them in 0.5% IBA (Dip 'N Grow) for 5 seconds, stuck them in moist peat and perlite (2:1) then put them inside with a plastic covering over them. I left them in a room heated to 75 degrees and the soil has hovered between 70-75 degrees. I have lifted the plastic 3 times a day for ventilation purposes.

I am misting about 3 times a day and have put a one tube fluorescent light 6" above the trees at night for 12 hours. I just read that these trees can be propagated under normal day/night light without lights so I stopped switching the fluorescent lights on last night.

Today I bought a Sunbeam heater blanket that has 10 settings and am using it as a less expensive solution to bottom heat as it covers a much larger area than most seedling heater mats I have seen. I am aiming for between 75-85 degrees bottom heat.

I am hopefully expecting roots to form after 6 weeks.

My question is:
I looked at the foliage tonight and 20-30% of it is turning brown at the edges. What am I doing wrong and how can I make sure the foliage remains green?

Thank you for any comments you may have.

Follow-Up Postings:

RE: Propagating Thuja Green Giant Arborvitae

  • Posted by Soeur z6b TN (My Page) on
    Mon, Sep 26, 05 at 22:52

You may have better luck taking cuttings in winter. Try it in mid-December to mid-January, bottom heat at 75 to 80 degrees, .8% IBA/talc, strip wound, peat/perlite 1:1 by volume, no mist. Usually I get 100% "take" on winter cuttings of Thuja and Chamaecyparis, and 80-90% on Juniperus virginiana and Tsuga.


RE: Propagating Thuja Green Giant Arborvitae

Thank you for your reply Soeur. I thought you could propagate them year round. Is 6 weeks a reasonable time frame to expect roots to have formed? Why would you not mist and how many times a day do they need watering and the plastic covering removing to ventilate them? Why do you think they are turning brown at the edges? So many questions...

RE: Propagating Thuja Green Giant Arborvitae

  • Posted by Soeur z6b TN (My Page) on
    Tue, Sep 27, 05 at 20:22

Woody plants are particular about when they propagate best from cuttings. I'm a professional propagator, and I can't think of one that offers uniform success just any ol' time you take a cutting. Conifers typically propagate best in winter, using the previous summer's growth. Six to eight weeks is fairly reasonable for roots to strike. This means that new roots are visible; they may be quite vigorous or may be just starting. It can take longer, though; don't give up for 10-12 weeks. Do begin feeding the rooted cuttings when rooting is actively underway. And don't transplant on until you have a good vigorous root system grown.

No mist because flat-leaved types like junipers, arborvitaes and such can get fungal problems when the foliage is kept wet. In my experience, the most important factor besides timing is correct medium (fast draining is imperative) and enough water and fertilizer. Tent the cuttings if they're on heat and you don't have them in a naturally humid situation like a greenhouse. But leave the tent partially open, not closed.

The brown edges indicate stress. Could be due to many causes, including wrong timing. I'd try again in winter.


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