Hey Red, no one can answer your question nearly as well as you can. We don't know what type of soil/drainage you have and can't investigate first hand, like you are able to. We also don't know specifics like how long it's been since you planted the trees.

I can tell you that .5 gallons is a very small amount of water and that twice per day is rather frequent for most situations. For instance, here in Tennessee I usually apply 5 (not .5) gallons of water at a time, once or twice per week, when planting a similar specimen. In hotter areas with well draining soil, more frequent watering would be necessary. Longer (deeper), less frequent watering is much better than shorter (quick), frequent watering.

I would suggest that you either use a spade or your finger to investigate soil moisture at a depth of at least a few inches. Soil at the level of the rootball should be kept moist but not wet. Surface level moisture should begin to dry in between waterings. Check the soil around and inside the rootball to ensure proper moisture levels. If rootball or backfill soil texture and/or structure is significantly different than the planting site's native soil, improper drainage can be an issue. In such cases, it is possible for the rootball to remain soggy while the surrounding soil dries out or for the rootball to dry out while the surrounding soil maintains adequate moisture.

Heavy clay with lots of rocks . Planted them in May. Holes were about 10-12 inches deep and mixed potting soil and native dirt were used to fill in around the root ball while planting When I check the dirt with a finger it seems dry unless just watered . Surface seems to dry after only a few hours but it is over 100 degrees every day lately . Thanks for the reply. Red

when i use my .5 gal per hour system.. i run it for 4 hours minimum... about every third day ...

i run it.. until the space between the emitters.. one foot on mine... meet ... that means i have a line of water on the surface.. and because of my sand.. i know it goes straight down ....

run as you wish ... dig small hole in between two of the plants .. and find out for yourself.. exactly what you are accomplishing ..... if the water is not at least one foot down.. then you are not getting water into the root zone ...

then... every other day.. dig at another emmitter... and start the water again... when the soil is drying near the top ...

most trees... conifers in this case.. like a drink.. and then near drying in between ...

without the benefit of ever digging a hole in your soil.. i will guess that you are no where near getting water into the root zone ... brandon is correct..

otherwise.. if the trees remain normal green .. in the heat of summer... you are most likely doing enough.. but wouldnt you rather really now???

ken

One of the reasons your rootballs may be drying out so fast is because of the potting soil amendment. That's a big no-no when planting trees, but hopefully yours will overcome the obstacle. Next time you plant trees, DON'T amend the soil. Amendment frequently inhibits good root system development and proper drainage.

Try watering more at a time (at least until the soil is moist to the level of the bottom of your tree's rootballs). Then keep a check on the moisture level (about 2" to 3" down, and especially in the rootballs themselves) and only water when the soil just begins to dry a little at that level. You'll have to be the one to determine the best timing, but I can't imagine having to water more than once per day with a sufficient amount of water (guessing - at least a couple of gallons at a time), even with very high temperatures. You didn't mention mulch, but hopefully you've mulched your trees well.

If the surrounding clay soil is sucking water out of your rootball quickly, you may have to settle on a happy medium between keeping the surround soil too wet and keeping the rootballs from drying out.

Below is a link to some guidelines that may help you with future plantings.

Here is a link that might be useful: Planting a Tree or Shrub

I disagree on your first point Brandon. There are instances when (some) mix (not a lot) benefits a tree in becoming established only because some soils are so inherently bad.

Ken gives the poster an ideal scenario to figure out what to do.

For me, however, 1/2 a gallon 2x per day is a-ok. I'm using common sense as a bridge to see what is occurring there and the math works for me.

Ken's approach however is bulletproof.

Good luck Red.

Dax

Dax,

Show my proof (scientific studies)! I've never seen even one that suggests what you suggest. Amending lightly is less likely to be harmful, but no amendment is almost always best. There are many threads here on GW that explain why amendment is detrimental. Here are a few summaries of the scientific findings:

from The Myth of Soil Amendments (by Sustainable Horticulture):

"There is a substantial and growing body of research showing that organic amendments provide no real benefits to woody perennials. Starting as early as 1929, numerous studies have shown that a variety of amendments (including sawdust, manure, bark, peat, and perlite) are detrimental to or have no benefit for plant growth (Whitcomb 1986). Amendments have rarely proved to physically benefit plants or soils, even in the first years after installation. Although the amendments may contain some beneficial nutrients or organisms, they are rarely the most efficient or best way to provide such benefits. Experiments have shown that root growth in unamended soil is better than or no different from that in soils amended with perlite, sawdust, or other materials (Phillips 1993; Hartman et al. 2000)."
...
"Attempts to find the optimal application rate of four organic amendments (peat, pine bark, vermiculite, and colloidal phosphate) showed that the optimal amendment volume was consistently none (Byrnes 1976). No amount of any of the amendments benefited plant growth, and roots were unable to grow outside the amended soil. In nine years of experimentation on six woody species in clay soil, Corley (1984) found no consistent, positive response to soil amendments; effects on plant growth were usually negative or neutral."

from The Myth of Soil Amendments (by Linda Chalker-Scott):

"No scientific studies to date show any measurable benefit of soil amendment except in containerized plant production. Plants grown in native soil consistently showed better root establishment and more vigorous growth."

RedGood,
I'm in Z8 Tx and typically water trees that size once per week at 5-10 gallons per tree during hot dry summer. We've had 42 days in a row of 100+ weather.
Not overly familiar with Green Giant hybrid so take my advice with grain of salt. Good luck.

Brandon I don't mean to cause a stir. Stick to your guns.

Only will I say I've spoken with people on GW with extraordinary circumstances where without a pick axe they cannot dig a hole and adding some peat allows them to keep the plant alive for establishment whereas without, it's a grave they've chipped.

Dax

Dax,

I'm not totally convinced that there aren't times when a small amount of amendment isn't somewhat beneficial to initial establishment. I even sometimes add a small amount of amendment to backfill in some cases. My big thing though is that most of the times people don't understand what they are doing when amending soil. I can't think of any good reason to add "typical" potting soil to GG planting holes. All it's likely to do is increase moisture during wet periods, decrease moisture during dry periods, and negatively impact root system development. One of these days a few of us need to get together and write a detailed explanation of soil drainage including the impact of amendments. It's been on my list for a long time, but I still haven't gotten around to it. Al Tapla has a decent start in the Container Gardening Forum, but I'd like to expand on what he's written and concentrate more on in-ground/natural soil aspects.

Here is a link that might be useful: Al's Container Soils - Water Movement & Retention

The important message in this thread is that the plants are likely much underwatered.

Dan

it is my understanding.. that peeps who have bad clay ... plant half the roots in the clay .. and then raise the mound with good soil ..

soooo.. in theory ... they totally amend the soil .. above grade ...

ken

"it is my understanding.. that peeps who have bad clay ..."

In a very poorly drained site, a large berm might be useful. The added soil isn't "amended", it's an added layer. I understand what you're saying, but I'm not sure the analogy is useful (and may be counterproductive to those that don't understand how drainage and soil texture & structure works).