Just because you don't know, doesn't mean he doesn't know. Again, here's how he bred the line in his own words:
DJ Short - The Origins of Blueberry
Choosing your parents
The place for breeding to begin is with choosing the parent plants, called the P1 generation. For best breeding results you use true-breeding stabilized strains as your P1's. Different breeders have different standards as to what qualifies as a P1. I have very high standards for my P1 generation. For me, the P1 must be either a fully acclimated, region-of-origin land-race variety, or no more than one generation removed, and crossed with itself or another highly similar, region-of-origin land-race variety.
I used three P1 strains to breed Blueberry, Flo and others. They were the Highland Thai (also called Juicy Fruit Thai, a first-generation Thai seed grown in the Pacific Northwest); a cross called Purple Thai which was a first generation land-race Chocolate Thai crossed once with a first generation land-race Highland Oaxaca Gold; and an Afghani Indica which came to me one generation removed from Afghanistan via the California/Southern Oregon growing community.

Juicy Fruit
The Highland Thai was a joy to grow and behold, despite its hermaphroditism. This plant grew fast, filling in any empty spaces with lush, green growth. It was a very slow finisher, 12 to 16 weeks and beyond in the bud period for most. It had the longest and skinniest leaves out of all the plants I have worked with. Thick side-branching is another characteristic of this variety.
The plant only periodically produced any kind of "tight" bud structure. Most of the buds were very loose, with some sporting long, slender shoots of widely-spaced single female flowers in a row (especially when grown hydroponically under halide lights.)
This bud structure is known as "spindly". Many of these spindles resemble threads protruding from a semi-formed bud. Each single thread averaged anywhere from five to ten inches long, some even longer, and consisted of a row of evenly-spaced female flowers and their corresponding bract leaves, anywhere from a quarter inch to one inch apart, alternating bract and flower in single file.

Thai
The entirety of the "thread" and bud structure was coated with sweet/fruity aromatic resin glands.
The overall plant color was dark, while the bud structures matured a lighter shade of green, sometimes green/yellow.
I was never able to get a Juicy Fruit Highland Thai to "over mature". I took one to almost twenty weeks into its flower cycle and she just kept pumping it out. Outdoors, one was taken in early-mid December from a greenhouse. The only difference was that the later harvest was a more stony, body high.
The finished product from the Highland Thai was an all-around champion herb. Though difficult to trim and cure, the outcome was fully worth the effort. It was a powerful, long-lasting and exquisitely flavoured herb with little or no ceiling. The high could last up to seven hours! The flavour, aroma and taste were a totally sweet tropical punch tutti-fruity all the way.
The Purple Thai was the other sativa in my repertoire. This was a first generation cross between the Highland Oaxaca Gold and the Chocolate Thai. This cross grew medium/tall and was very symmetric in structure. The side branches were shorter and, if left alone (untopped) the main stalk (meristem) remained the dominant shoot.

Afghani
The entire plant of the Purple Thai was very dark-coloured and would express a deep royal purple colour at the slightest exposure to cold. It did not exhibit any of the spindly bud syndrome of the Juicy Fruit Thai, and the finished buds were a medium and compact sativa type. The finished product was equally as fruity and strong as the Juicy Fruit, also without ceiling.
For whatever aesthetic reason, I preferred the Purple Thai to the Juicy Fruit Highland Thai. I believe that the Purple Thai was emotionally kinder or gentler than the Juicy Fruit. At larger doses the Juicy Fruit could evoke quite a terror, especially when combined with psychedelics. Though no less potent, the Purple Thai seemed easier to handle, including when tripping. The Purple Thai was one of the first to show resin gland production in the early bud cycle, at roughly three to four weeks into the cycle. It also matured at 10 to 12 weeks indoor, and early to mid November outdoors.
The Afghani Indica plant is short with large, wide leaves, stout and thick-stemmed. It has early to very early maturation, producing large, dense buds that smell earthen to skunk, with a strong smoke that is generally sedative or "down" in effect. Though consistent in its growth and overall effect, its appeal is somewhat limited in my opinion. I believe more indicas should be made into hashish, which is where the finer qualities of the indica appear.

Blueberry x Afghani
The sinsemilla Afghani Indica first showed up on the market in 1979. They were huge, green, stinky, sticky, dense buds of potent, pungent herb that smelled like a skunk and produced a narcotic-knockout stone that was tremendously novel, when compared to all the sativas that had come before. This was right after sinsemilla herb hit the market with big appeal.
The triad of sinsemilla, indica, and the advent of high powered halide and HPS lights, all wreaked havoc on the breeding programs of most pot-entrepeneurs. Few people maintained their sativa lines, and the strains virtually disappeared from the commercial markets. The short, dense, early-maturing and body-powerful indica has dominated the scene since 1983 a matter of disjointed economics.
Such were the three main P1's I used for my breeding lines.

Afghani male
The f1 cross
The f1 cross is the first cross between two distinctly different P1 parents. The "f" stands for filial (child). I cannot overstress the importance of the two P1 parents being as genetically different as is possible. It is this initial genetic diversity that leads to the most possibilities in succeeding lines.
If the P1's are sufficiently diverse, then the f1 will be a true hybrid, expressing a near total uniformity and great vigor. It is in the crosses beyond the initial f1 (especially the f1xf1=f2 cross) that specific traits are sought. There will be a tremendous amount of variance in the f2 crosses of f1's obtained from a female pure sativa and a male pure indica.
The Blueberry (among others) was discovered and stabilized from an f1 cross between the P1 parents of a female Juicy Fruit Thai or a female Purple Thai and a male Afghani Indica. Thus there were two possible routes to essentially the same finished product. Blue Velvet and Flo seem more accessible via the Purple Thai route, while Blue Moonshine seems more accessible through the Juicy Fruit lineage. That is, there is a higher probability of occurence of the specific traits which I'm seeking, and so they're easier to "find".
Oddly enough, the opposite cross (female Afghani indica crossed with pollen from male Thai sativa) was not nearly as interesting. The f1's from this cross were more leafy and less desirable. They were also more hermaphroditic and subsequent breeding revealed them to be less desirable. It has been my observation that in a successful cross, the (usually female) sativa contributes the type of aroma and flavour, while the (usually male) indica contributes the amount of aroma and flavour to the prodigy. So far this observation has proven fruitful.

Blue Moonshine
So the Thai female is pollinated with the Afghani male and an abundance of seed is produced. The seed is uniformly sized and shaped; small, ellipsoid and mottled with dark stripes upon a grayish brown shell. A single female is capable of producing thousands of seed, leaving plenty for experimentation. This is the f1 generation, which I called simply "The Cross".
The plants of The Cross grew uniform, medium-tall "spear" structures of many competing side-branches around one main (meristem) stalk. Large, long buds formed along the branches. There was a wide palate of colours, especially among the Purple Tha
Thanks again Jogrow.
I have read this info many times, many years ago. His "expertise" is what stoked me in the first place to by the "original" blueberry. I figured with his extensive knowledge and hard core selection process that it was going to be an amazing strain!!
I was not as impressed when i grew it however........i had many phenos from my seed pack. Short over bushy pheno, chistmas tree shaped one, indica looking one, and some others. I had one that was soooooo friggin beautiful! All the colors of the rainbow, buds were dense w/mega resin, and smelled like blueberry yogurt. Cured for over three to four weeks in a perfect drying enviroment before i trimmed them. No flavor ay all.....and you couldn't get high!!!!! Couple of the other phenos were very good.....knda hasy with some blue flavor and pretty potent, but no blueberry flavors, and nothing that fit his description!
So i question his selecting. I know he talks a great talk......but the walk didn't walk the walk! Why sooooooooo much variation if he went to f'5?
And i still don't see about either a highland thai(juicy fruit) OR purple thai? Did he use both as he kinda hints to.....or is it one or the other?
I don't really question what he knows......but more of how he applies what he knows to what he produces.
