Propagator...Heat mat..or Warming cable?

Posting in this forum as it's only really going to be used for veg.

Due to the forum "2013 Onion thread" and the lovely Loli's help I'm now the proud owner of some Suuuper Duuupa giant onion seed, and I intend to give them the best start that I can.

I've had a little surf at the likes of BnQ, Wicks and Homebase, only Homebase had a heated propagator for a shocking £38, then checked good olde Fleebay and it's stuffed full of them (think someone was selling the same one as Homebase for £19 plus £5 p&p)

Then I noticed Heat Mats, and thought that they might be a better option for me, ie maybe easer to move my half dozen cheap plastic unheated propagators on and off it as needed.

But then I noticed Warming Cables, and I'm getting even more excited about this idea, I measured my sitting room window sill, its 3 meters by 300mm, I really only grow veg from seed, and this would be the mother of all indoor heated propagators (well in Potty Land anyway lol) to push larger batches of plants out into the garden, I'm thinking a simple sand filled 3mtr x 300mm box, and either my smaller seed trays and lids sat on the sand, or maybe a better idea would be a custom made cover, I'm pretty good with wood and more than capable of mould making and vuc forming covers.

So what do we think? has someone made one before? what is the debth of sand required?

any thoughts on this cable?

http://www.ebay.co.uk/itm/6-MT-SOIL...416?pt=LH_DefaultDomain_3&hash=item5891da1c20

and this Thermostat

http://www.ebay.co.uk/itm/THERMOSTA...754?pt=LH_DefaultDomain_3&hash=item5891e10312

it says 18 to 36 degrees, is that about right for veggies?

Many thanks, Plant Potty

 

One point you should keep in mind is that the heater cable (my choice - I have two)! is that it must be in very very damp sand or it may overheat and fail, the damp sand carries the heat upwards to heat the pot bases. So the propagator you talk about will weigh quite a lot.

I would tend to keep to the lower temp' limit.

Cheers, Tony.

 

Thanks, Tony, I was wondering about water and the base, I have some "Z-Poxy" its a very expensive but bullet proof clear epoxy varnish that I was thinking about water proofing the inside with, the outside can have my cheap varnish lol the window sill is solid brick, so the weight wont be a problem.

what debth of sand do you have?

Thanks, Phil.

 

I would want to keep a sand+warming cables jobbie out of the house. Very heavy to move, and not very house-friendly.

I'd go for the reptile heating mats (cheaper than anything with "horticultural" in the name!), or a windowsill propagator - I've got a couple of Garland ones, no thermostat, just a gentle bottom heat and they fit 1/4 sized seed trays / lids (which come with it, but worth buying spares as the seeds will be in them for, say, a month before pricking out, but will germinate in, say, a fortnight - so with a spare set of trays you can sow a second lot after two weeks, having moved the ones that have germinated off the heat to another windowsill or the greenhouse etc.


http://www.thegardensuperstore.co.u...Electric-Windowsill-Plant-Propagator-G51.html (much cheaper available, so this just to give you the idea)

Either way, I would have "Multiple units" so that you can just heat part of the windowsill if you only have a few items on the go - rather than one socking big 3M heating pad. 3M x 300mm is going to need a 6M soild warming cable, which is 75 Watts ... that's quite generous when you are only using 1/3rd of it!

 

Just had a look at reptile heat mats, and found they are indeed much cheaper than similar things with 'horticultural' in their title.

I'm guessing a thermostat might also be needed, so I look at those on the same site. Here's an example:

http://www.reptiles.swelluk.com/rep...hermostats-555/habistat-mat-stat--245565.html

That seems to be one of the cheapest, and is designed for heat mats upto 100 watts. Given that the small heat mats are not that much cheaper than the larger ones, I'm wondering if it might be worth going bigger, just to 'future proof' things a bit.

 

Worth having one eye on the running cost.

1 Watt, on 24/7 for 4 months (Jan - Apr) costs about 50p. Therefore 100W = £50.

of course thermostatically controlled it will be less - 50% on do you think?

Thus I think better to have 2 half-size (or maybe one 1/3rd size and one 2/3rd size) so that you can just turn on as much "heating area" as needed.

Worth a look on eBay - there are loads of Reptile/vivarium warming/heat mat/pad - pick the search terms you fancy!

 

I wonder if the cost of heating could be significantly reduced by the fact that once germination has happened, then the heater can be switched off?

I might have this wrong, but I think that once germination has happened, a relatively cool environment is what we want, so that the seedlings are less inclined to grow too tall and leggy in the less than perfect light. I'm thinking that even with a grow light, unless a lot of effort and money is spent, then the light just isn't going to be as good as that of a perfect spring, so I would guess its more important after germination to provide conditions more for root development than top growth (ie comfortably warm compost, around room temp, but cooler top side)?

 

In my case the next batch of seed trays will be on the heat mat - once they germinate (plus a few days) they come off the bottom-heat.

I have a sowing schedules, based on fortnightly sowings, staggered so that the things that grow slowest / take longest to develop are started first, and basically the bottom-heat space is free after 14 days for the next batch (some things take longer, obviously)

This also means that I need several trays as the early batches tend to be a while before they can be pricked out; space for pricked out plans increases as the seedling season progresses - but that is fine as I turf out things in the greenhouse that have been overwintering (hardy, but grow better if protected - pot grown hedge cuttings, for example).

 

Thanks Kristen, lots for me to think about, I dont have a greenhouse (yet) so the sitting room window sill is where I start everything off, after using it for two years I deffo need to make a full size tray of some sort as I'm always spilling water :(

I understand what you're saying about a smaller Matt area, and the cost savings involved, I need to measure the temp on the window sill to work out how much heat would be required, maybe not much?

Thank you for the food for thought

 

Propagators and heat mats are suitable for use both indoors or greenhouse (or both if you have 2), unlike a great sand filled bench with a heating cable.

You may wish to think ahead incase you get a grow light and what size(s) will fit under it best.

 

Thanks Scrungee, I have been pondering about a grow light. and re~use when I get a greenhouse, at the moment it seems the more I think about it the less I know

 

There's another thread on Lights which is active at the moment:

http://gardenerscorner.co.uk/forum/threads/grow-lights-heaters-etc-on-a-budget.47293/

 

Thanks Kristen, I have been following that thread, such alot to think about lol

 

Don't forget that square pots make the best use of propagator space (and possibly utilising the heat even further by not having gaps allowing heat to escape?).

Getting even more penny pinching, I've got somebody at a local garden centre saving square, coloured pots that their hyacinths come in - they're colour coded to indicate flower colour for use so the white ones will be used under grow lamps to reflect more light. The rest will get used as I've mentioned in the scrimpy label use thread.

 

Just make sure you have a soil thermometer! I have 2 electric propagators, 1 with a thermostat and one without, both need adjusting with the aid of a soil thermometer, I just add/remove more sand from the base to get the desired temperature in the soil. In very cold weather I cover the propagators in bubble wrap!