Need Advise on Growing Cuttings Under Flourescent Lights

rokal(LongIsland/z6b)July 15, 2005

I took softwood hydrangea cuttings yesterday and have them about 8-10" below 4ft shoplights (2x32W cool whites) in my basement (room temp is 60-65 degrees). The cuttings are in 4" pots, grouped together in a 1020 flat. The entire flat is wrapped in a large clear plastic bag with no vent holes. The top of the plastic is suspended about 6" above the cuttings.

How close should flourescent shop lights be to newly taken cuttings (or plastic) and how long should I run the lights? I currently have them on a timer for 18 hrs.

Is there anything I need to be concerned with (e.g. misting, ventilation)?



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Millie_36(Z6b MO)

I think you are right on track. I think you could get by with 14 hours of light, but doubt that it matters that much since they are happy in full shade or part sun.

I am doing mine in a North window with no additional light using the method linked below...with the exception that like you, I am using a humidity chamber. It is 90+ degrees here, now, so don't think they would be happy outdoors with a spritz of water now and then.

Here is a link that might be useful: Hydrangea Propagation

    Bookmark   July 15, 2005 at 5:37PM
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georgez5il(z5 IL)

Ventelation is important to prevent the formation of a fungus & misting will be needed if tent removed & MAY be needed to maintain high humidity.

    Bookmark   July 15, 2005 at 6:18PM
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Millie_36(Z6b MO)

George may be right with a larger humidity chamber. I never have the problem with soda bottles...always have plenty of condensation. I just take the caps off after about one week...they still maintain condensation, but have ventilation. I have never tried a larger chamber. Have thought about building something using PVC pipe for a frame work, but the soda bottles are handy and work.

I found the link I posted above interesting in that it should produce stockier plants. I would not have known that Hydrangeas root along the stem as well as at nodes. I had never bothered with them before because they are so good at doing it on their own. I knew that Clematis root that way and had done them many times.

My book on propagating woody ornamentals only says, "prepare cutting." Not much basic info there.

    Bookmark   July 16, 2005 at 7:23AM
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Thank you Millie & George. I will increase the ventilation and be prepared to mist at the first sign of wilting. So far the lights and humidity chamber have only increased the soil temperature about 8-10 degrees.

Millie, I read the Nantucket Hydrangea article and also the instructions found at the following URL which recommends using a leaf node below ground and wounding the stem:

Propagate Your Shrubs from Softwood Cuttings

I tried several cutting using both methods so it will be interesting to compare the results.



    Bookmark   July 17, 2005 at 10:59PM
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Millie_36(Z6b MO)

I think you will find that both will root. The site has very good basic information for general use, but some plants will root along the stem and some need the node/bud area for best rooting, and she was giving advice for garden shrubs in general. Same with wounding the stems..some plants need to have that done to increase the chances. Since I know that Hydrangeas will root if a stem just lays on the soil, I didn't bother to wound the stems.

I save all the really large plastic bags that rolls of paper products come in if they are partly clear plastic. I can set a whole tray of little plants in them and tie it shut. Instead of using sticks to hold it up, you can tie the top up to whatever you can find...or just hang is by a length of cord. After a period of time, I cut a slit in one side and can reach in to check for roots or spray with water. The slit will close enough to keep the humidity up inside.

Strange looking things can be found anywhere I have been. LOL One of these is hanging from a shop light fixture, right now, full of Ajuga cuttings. I like Ajuga for very large containers for color and trailing habit.

    Bookmark   July 18, 2005 at 8:30AM
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I snapped a few digital photos of my setup today:

I sure hope this works!

Millie, are you going to put your rooted cuttings outside for the winter? If so, how do you protect them?


    Bookmark   July 18, 2005 at 10:32PM
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Millie_36(Z6b MO)

Look great to me...Lots of humidity. I still haven't taken the caps of the bottles. Do you see any sign of buds swelling, yet?

I am propagating mine for other people, but I would plant them out. If concerned about them, just cover with a bottomless gallon milk jug and pull mulch up around the jug. I use some stakes to hold the bottles or jugs in place. I believe they are hardy through zone 5, but I do loose terminal buds once in awhile. I have never lost rooted stems that lay on top of the ground without cover of any kind.

Your set up will work with many other plants...mine has gotten lots of use over the years. I keep Mandevilla plants over winter under mine for one thing. Have to do lots of clipping to keep them in bounds, though.

    Bookmark   July 19, 2005 at 4:33AM
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Hi Millie,

Thanks for the over-wintering tip. I'll give it a try. No sign of swelling yet but I am optimistic ;0)


    Bookmark   July 20, 2005 at 9:34AM
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Ok now I'm hooked! I have 100% success rate with my cuttings. All are well rooted in 3 weeks time.

My question is how should I transition them out of the propagation chamber and harden them off outdoors?

I was figuring on opening up the plastic a little more each day for about 3-4 days. Then, when the plastic is removed, place them in the shade, outdoors, for a couple hours a day.
Gradually, introducing them to the partly sunny conditions they will ultimately grow on in.

Does this seem like the best plan? Also, should I start treating them to diluted fertilizer applications?


    Bookmark   August 11, 2005 at 3:14PM
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Millie_36(Z6b MO)

Can I say I told you so, now? LOL They really are easy to do. Your plan sounds good to me. Easing the cover off is a good idea and then you can spray them with water and leave the cover off as long as they look good. Spray them with water outside, too, as long as they are in full shade. It will help transition them to the real world.

Did you notice the one propagator said to just place the cuttings outside and spray with water a couple of times per day? I think a lot depends on the outdoor humidity and the temp.

I have treated mine to dilute fertilizer. They have roots showing on the bottom of the pots...time to pot up to gallon size, I guess. I didn't loose any either. 5 new plants from one short branch. I used a single set of nodes/leaves for each cutting. It helps to learn which plants will root along the stem...stretches your cutting material. Clematis will root anywhere along the stem, also.

    Bookmark   August 11, 2005 at 9:16PM
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Okay, Okay, Okay, you told me so. There, I've said it ;-)

Thanks for validating my plan Millie. I'm gonna start them on diluted fertilizer tonight.

Did you notice the one propagator said to just place the cuttings outside and spray with water a couple of times per day?

Yes, orginally I tried that method but I failed. It was just too darn hot. Dispite my best efforts to mist them regularly, they wilted and the leaves dropped within 48 hours.

I'm really glad the indoor method worked out so well. I've used my light setup to grow lots of seedlings but this was my first attempt at cuttings.

Thanks Again,


    Bookmark   August 12, 2005 at 11:19AM
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Millie_36(Z6b MO)

LOL Don't forget to try other woody ornamentals....if so inclined. I have done everything from roses to oleanders under my lights. Some are easier than others, but you already know it can be done.

    Bookmark   August 13, 2005 at 8:24AM
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