This hot weather is great for flax germination but we're all having to water our seedlings. This first two to three weeks after planting is pretty much the only time you'll need to water the crop, and the weather is going to turn cloudy and rainy at the weekend, so no more water will be needed then.
A flax shirt takes 6.4 L of water to grow and produce. A cotton T shirt takes 2,700 L. That's the amount of water one person drinks in three years. For more on how unsustainable this is read about how cotton production drained the Aral Sea http://ejfoundation.org/cotton/cotton-and-water.
As you will have noted as you prepped the soil for your flax, it needs very little nitrogen based fertilizer. Cotton is what's known as a 'greedy feeder', needing large amounts of nitrogen and unless you're producing organic cotton, all of that nitrogen is processed from oil. It's the 3rd highest user of nitrogen of all the crops (including food crops) we grow worldwide.
You may also have noticed that I haven't mentioned any pesticides you need to add to your growing flax. That's because it doesn't need any, unlike cotton which uses 25% of the total world's pesticides in its production http://ejfoundation.org/cotton/cotton-and-water.
Find more information about cotton productionand the pesticides and toxic chemicals used in its production here, http://www.novozymes.com/en/sustainability/Published-LCA-studies/Documents/Comparative%20LCA%20of%20a%20t-shirt%20produced%20with%20biotechnology%20and%20conventional%20technologies.pdf
As you'll see by August, linen can be produced without any chemicals at all.
A linen shirt has a LCA (Lifecycle Assessment - the amount of a resource it will use from production, through wearing until it is discarded) of 130g of greehouse gases. A cotton T shirt (with less fabric) has an LCA of 410g of GHG.
I personalised this linen shirt, bought at Value Village by embroidering on it. The embroidery says Sown, grown, rippled, retted, scutched, hackled, spun, wovem, bleached, sewn. LCA 6.4L of water 130g GHG. I wanted to remember how much work and energy went into it, and why buying clothing second hand is so much more sustainable than buying new. And shipping our second hand clothing around the world to the countries who manufacture them, but are too poor to buy them new, just adds to the carbon footprint and destroys the local weaving traditions and ethnic clothing.
70% of the LCA of all your clothing is down to you. Only 30% of the GHG of a piece of clothing comes from its production and manufacture, the rest is down to your washing and drying. If you want to seriously reduce your GHG production than you need to wash in cold water, and always air dry (because most of that GHG is from using the drier).