sources of 'bottom heat'

MadameMeowFebruary 5, 2013

I'm going to try rooting currings this year, and many posts suggest application of heat on the trap bottom. The seed starting mats I've seen at stores are $35 or more, same as heated pet beds. Heating pads now turn themselves off after several what are you all using for the heat source? Please advise,

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rhizo_1 (North AL) zone 7

I've used heating cables for over 40 years. This will only work if you sow your seeds into a flat for germination, transplanting them to their cells packs in a week or two when heat is no longer needed.

Heating cables have an in-line thermostat that regulates the temp. They are placed in the flats before adding the medium. Once all of the seeds have germinated, the cables are unplugged.

    Bookmark   February 5, 2013 at 9:00PM
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ken_adrian Adrian MI cold Z5

i have a thin sheet of plastic with heat trace thru it.. bought years ago.. from a beer brew/hydroponics store.. constant 72 degrees .. since i do it in the cold MI basement.. its on all the time ...

i dont know what you need.. since you really have told us anything about your plan .. other than you are going to do it.. and think you need this .. are you sure you need it for what you want to root.. not everything needs such.. especially in z9 .... why cant this be done outdoors.. etc ...

but you only asked what i have.. not to help otherwise.. have a great day ...


    Bookmark   February 6, 2013 at 9:46AM
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calistoga_al ca 15 usda 9

Because my bottom heat is a 3x6 foot plate, maintained at 70 degrees, it is used for cuttings simultaneously with seed starting. Cuttings are in four inch pots, while seeds are in pony packs as well as root trainer flats, all sitting directly on the heating plate. As germination occurs the pots are lifted four inches off the plate onto inverted pots. This lowers the soil temperature, while moving the seedlings closer to the 400 watt HID light. The light is only on 12 hours a day so it does not raise the soil temperatures as the plate does in my unheated greenhouse. Al

    Bookmark   February 6, 2013 at 9:58AM
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How interesting! Thanks to everyone for you replies; I have never seen a plate mentioned before, but it sounds great! Heating cables, I'm a bit fuzzy on them; it must be something made special for warming the soil. BTW- the hydrophonics forum mentioned an aquarium heater, which sounds good in a soiless environment.

And, thanks, Ken-there is a hydrophonics store locally, I'll have a look at what they have on offer. sorry my request for information was sketchy.
I am going to attempt (again) to root:
Osmanthus fragrans (sweet olive)
Daphne odora marginata (winter daphne)
Jasminum Sambac (arabian jasmine/true jasmine)
A "madagascar jasmine' I lost the tag and don't know the real name.
French Lilac
Violetta de Bordeaux Fig
and start seeds- tomato, pepper, white oak,mimosa (albezia?) I dunno- I tour the neighborhood and see what I can find.
so, you'll note the cuttings are semi-hardwood, or somewhat tropical in nature. I'm hoping to improve my odds with a bit of warmth at the bottom.

thanks again for your replies,

    Bookmark   February 6, 2013 at 6:40PM
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squirrellypete(z7b AL)

Firstly with respect to seeds, I do my germinating in a top floor home office bathroom where the air temp already stays between 70 and 80 on its own since all the heat from the woodstove and HVAC system rises to the top of the house. That may be kinda cheating since not everyone may have a space during the winter that will stay this warm to set up their flats. But if you can, put them in the warmest room of the house to aid in this and lessen or eliminate any additional heat you may have to provide.

In addition, I have one shelf on my homemade plant rack dedicated to germination only, and it's placed directly above two fluorescent fixtures that are lighting small plants beneath. Fluoros do not produce much heat compared to incandescents but they still produce some heat, and what rises off of these two fixtures seems to keep the soil of the germination trays above them at an appropriate temperature to assist speedy germination.

Just some ideas to think about. Other folks swear by putting on top of a refridgerator but I've never found ours to be very warm on top.

    Bookmark   February 6, 2013 at 8:04PM
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ken_adrian Adrian MI cold Z5

most of your stuff is 'woody' material.. special rules for such ....

i suggest you look into the gospel according to dirr ... see link ...

i borrowed the book.. i suggest you peruse it at a library.. before investing ... as it wont be cheap ...

he may have more than one book.. so check him out completely ...

heat cable.. is buried in a sand bench ... most likely way over what you will be doing ...

you inspired me to do a post in the conifer forum.. here is the link:

maybe that will give you some ideas ....


Here is a link that might be useful: link to dirr book

    Bookmark   February 7, 2013 at 11:59AM
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Ken, Thanks again! My county library HAS the book you recommend PLUS one from Dirr for warm climate shrubs; I have to wait for them to transfer the books to my local branch, but I'm very excited to learn about this! And, thanks also for your pics on the conifer forum; I have a metro rack I can set up in a similar fashion in my office, so I don't forget it's there LOL. My only challenge now is my office cat- Muse- a siamese who wants to play with anything interesting or new in her room. The orchid roots are bare due to her picking out the bark to play...exasperating, but you gotta love her ingenuity!

    Bookmark   February 7, 2013 at 12:25PM
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ken_adrian Adrian MI cold Z5

i am intrigued by the warm climate book ...

you might also want to research nearing frames.. which is an inground rooting system ...

a lot of this heat and warmth thing.. is for us in the great white north .... where its was a blistering 22 last night ... so i MIGHT think a z9 person might not be as restricted on warmth as we are ...

so do try to limit your research to your zone ... e.g. reviewing a thesis from antartica.. which favors method A .. just might not apply to you ... lol ...

you local extension office.. might be able to help you also ...

dont know what to tell you about the cat ... i am sure she would find a way to knock all the plants off.. to sleep on the heat mat .. lol ...


    Bookmark   February 7, 2013 at 1:30PM
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When testing germination or starting seeds, I found that the space above my under-counter lights and the ballast of the fluorescent light above my sink (always on) is perfect! and Fast!

    Bookmark   May 21, 2013 at 7:21PM
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david52 Zone 6

After 15 years using the same, standard bottom heating mats for both cuttings and seed starting, I'm convinced that they're worth the price. They work better if I place a layer of styrofoam under them.

Here is a link that might be useful: link to standard heat mats

    Bookmark   May 23, 2013 at 11:29AM
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