[Trikidiki]

I just use an old soil thermometer if I am unsure if the ground is warm enough for seed sowing... or even my fingers.

I thought one was supposed to use one's buttocks.

I admire your creativity Trikidiki but I could not cope with all that over the growing space we have though

No plans to do it on a regular basis or as a guide to when to sow but as BabbyAnn said, just an experiment to see if there is a benefit in using either clear or black polythene from a soil heating perspective.

I like tinkering with this sort of thing, it keeps my mind active. The bits will then be 're-purposed' to control the solar heated propagator I am building which is also just for fun and probably won't get put to serious use unless it works better than expected.

[Yorkie]

I just use an old soil thermometer if I am unsure if the ground is warm enough for seed sowing... or even my fingers.

I think it's time for the annual reminder to people of the traditional (anecdotal?) method of seeing whether the soil is warm enough ... with a bare backside! 

[harrymac]

I think it's time for the annual reminder to people of the traditional (anecdotal?) method of seeing whether the soil is warm enough ... with a bare backside! 

Not with the amount of glass I still find when I'm digging! 

[Trikidiki]

Not with the amount of glass I still find when I'm digging! 

You think you have problems, I have to contend with Mesolithic flint blades.

[Yorkie]

Not with the amount of glass I still find when I'm digging! 

You think you have problems, I have to contend with Mesolithic flint blades.

Ah well at least that's history you can be proud of 

[Trikidiki]

I started the 'Great Polythene Temperature Experiment' today.

Details are on my Diary http://chat.allotment-garden.org/index.php?topic=122319.0

I will update here when I have some more data.

[upert]

From an environmental viewpoint - what is this sheeting made from? Oil isn't it? I sure have dug a lot of it out of my plots.

I chuck some manure on some of my beds and leave it... maybe put some cardboard over that too. I must admit I'm becoming more idle though so I might go down the plastic route instead of weeding. Plus the next fella can have fun digging it all out. 

[Trikidiki]

From an environmental viewpoint - what is this sheeting made from? Oil isn't it? ........

The same sort of material as plant pots, seed trays, water butts and watering cans.

[Trikidiki]

I have logged a week's data and graphed it in Excel, the output graph I have posted on my diary pages:

http://chat.allotment-garden.org/index.php?topic=122319.0.

[BabbyAnn]

interesting - at the moment it looks like clear seems to be warmer than black.  That's been quite a useful exercise

[Salmo]

I have it somewhere in my brain that to warm soil black sheet has to be in contact with it whereas clear material is best as a cloche with an airspace. The problem with clear material is that any weeds have light and grow fast. Under black sheet they become white and leggy and eventually die.

[Trikidiki]

 

I have it somewhere in my brain that to warm soil black sheet has to be in contact with it whereas clear material is best as a cloche with an airspace. The problem with clear material is that any weeds have light and grow fast. Under black sheet they become white and leggy and eventually die.

In both cases here the sheet is in contact with the soil with the surface sensors lying on the surface with the polythene directly above them.

I am aware of the weed growth difference but this experiment was solely looking at the heating effect. People can draw their own conclusions as to whether any extra heating is worth the possibility of more weed growth.

Any seeds which require light to germinate will 'suddenly' germinate when the back plastic is removed, ie just when you may be sowing your seeds. I would prefer that any weed seeds germinate under the clear polythene while I am preheating the bed, I can easily remove those weeds prior to planting or sowing.

[BabbyAnn]

maybe both black and clear could be applied for a more effective soil warming effect?  Black on surface with clear on top?

[Trikidiki]

I have logged another week or so and graphed it in Excel, the output graph I have posted on my diary pages:

http://chat.allotment-garden.org/index.php?topic=122319.msg1446034#msg1446034

[Trikidiki]

Latest results

http://chat.allotment-garden.org/index.php?topic=122319.msg1446792#msg1446792