To give your seng beds more light check out the area due east of your beds for trees that could be cut back or eliminated completely to let in more morning light.
If you are like me and are growing seng in some decent timber land you may not want to shed any nice oak trees but you could eliminate some trash trees like dogwood, sourwood, ironwood, etc..
Remove or cut back only the trees that are blocking morning sun and leave the ones that are offering evening shade.
Below is a pic that demonstrates well how the site can make a big difference in results.
The 4 roots on the upper right side were all 8-10\" 3 prongs and were all 20+ years old (long root necks), with around 1/4 oz roots. They were growing on some old timber land that offers deep shade and the soil is mostly clay with some leaf mulch on top. I expect the calcium levels are low.
The roots on the bottom and left were all in the 5-8 year old range (short root necks) and much larger in the 1 oz to 1.5 oz range. The tops were big and stout 3 and 4 prongs. They were found growing just a 1/2 mile from where those other roots were found, but in a site that was quite different. They were growing around the bottom of a limestone bluff, the soil was just full of rock chips and leaf compost. The bluff was facing east and the seng was getting very good morning light, but were shaded well in the evenings.
That may be the ideal setting to grow big seng with less time.
TNhunter