What would we realize if we assume a soil that was saturated in the AM, then assume a day-long sun load, and further assume we are dealing with trees planted in bare soil (if it's not bare soil, the vegetation would shade the soil and a relatively insignificant amount of passive heat would be generated at the soil surface)? That's three assumptions we need to make before we start, so we're starting to look like the model set-ups that "proved" global warming. ;o) We would then also have to assume that there actually is a way to practically apply the idea that there is a critical temperature that kills the plant. I'll explain why that is technically true, put practically speaking - false. Even if we were dealing with trees in a bare soil, how much water remains in the soil by days end if we water it in the AM so it has a full day to 'absorb' heat? Only a minute amount in micro-pores and a microscopically thin layer on soil particulates - so not much of an addition to the soil as a heat sink. We also need to take into account that we KNOW the cooling effect of evaporation is greater than the sunlight that strikes water's surface. Case: The sun that passes through a water droplet on a leaf is capable of generating only .2 calories per minute, while a drop of water absorbs 3.75 calories as it evaporates; so the net effect of a a sun load on a wet surface is to cool the surface considerably as long as it's wet. When the surface dries and starts to warm, it increases the evaporation rate and heat absorption at increasingly deeper soil levels. Soil is a fairly poor conductor, and becomes an increasingly poor conductor as the volume of air in it increases. So, as what water remains in the soil evaporates, it reduces the effects of passive solar gain by absorbing a good portion of that heat. As the sun load decreases (dusk) the soil loses heat fairly rapidly, primarily through conduction and radiation, but also aided to some degree by convection. I'm unable to find where watering before a freeze would make a significant difference in soil temperatures over a cold night. We also need to examine the idea that "... the difference between life and death for a plant is a critical temperature over a critical period." I'll say briefly that the 'critical period' part is far less important than the 'critical temperature'. When bound (intra-cellular) water freezes, cells die as ice crystals destroy the cells. This usually happens in any plants planted out in the hopes they will survive the areas low temperatures (Lou's) at some temperature several degrees below freezing. While we can allow there is only 1 degree of dead in any organism, it's not practical to assume that the organism simply collapses at a given temperature. Neither roots nor shoots die in concert, they die incrementally. The softer/newer/more herbaceous tissues are the first to succumb to chill injury, with the injury progressing through more lignified and resistant tissues as the temperature falls. This fact effectively eliminates the thought that we can practically apply the idea that any finite temperature = the end of the organism. The best we can practically claim is that IF watering in-ground trees has any value at all, it would be limited to reducing the extent of chill injury. If we fall back and try to reinforce the idea that death is death, we need to look at the moment immediately before viability ends. At that point, what we are left with is not a tree we are likely to want. Al

I planted 120 Black Walnut and 100 pines about 2 yrs ago. Planted them on some property in north Louisiana and they had a drought that year. Lost all but 30 pines. Last summer planted 200 pines, another dry year, but not so bad, 1/2 of them made it. Its just a roll of the dice. When planting here in central Texas, I can only water about 15 trees remotely by tank (limit of my time and the tank). Anything extra I plant I try to pick drought tolerant native stuff and locate it where it may get a little more than normal moisture. I believe only about 1 year in 4 is our weather conducive to establishment of seedlings here. Pick those you most want to save and leave the others to nature. In future try to locate trees where they receive extra moisture or limit yourself to what you can water. In nature, trees only grow in areas where their seedlings can survive.

About 10 gallons/tree at the drip line and out about 3 feet is about right;

Last year a friend decided to hire a gardener to remove his lawn. The gardener decided the easiest way to do it was to simply cover the lawn with landscape fabric and top that with mulch to achieve a uniform look, ignoring the lawn trees. This spring when the winter rains stopped my friend noticed the leaves on one tree were all dying and falling off. She came to me and asked what could be wrong. It was pretty obvious that a tree planted in the lawn 20 years was dependent on the lawn water. To save the tree I made a loop of T-Tape at the drip line and put it on a drip timer until she hires a landscaper to actually remove the dead lawn. The tree has comeback while the cheap landscape fabric has turned to dust and the weeds are now growing after the first rain. The lesson is the cheapest remedy is not always the best. Al