I planted a Tilia Greenspire at the end of Mar '08......Eastern Fraser Valley.My soil is a good mix of clay and sandy gravel. I've been watering it faithfully but mostly guessing the amount...checking 2inches down for moisture. It has leafed out and is looking good. How much is enough. This morming, my guess is I gave it 40 litres.Is that enough or too much.....the temp climbed to 30C today. I need a confident reply please. Sorry I forgot to rotate image. Thank you.