Ask Mr. Smarty Plants

Holly shrubs are dioecious and need a mate, so you can correctly reason that the lack of berry production must be attributed to one of two possible causes: You have a male holly shrub OR you have a female holly shrub, but its flowers haven't been pollinated. Ordinarily, this is pretty hard to determine, but in your case, the cultivars of Ilex verticillata (Common winterberry) that you have include 'Nana' which is female and 'Jim Dandy' which is male. In many cases, it is not known which sex of an Ilex is being purchased from a nursery - mostly clones are sold in nurseries.  Both sexes have flowers, but only the females will produce berries. Since you know you have male and female plants, we might guess that the immaturity of the plants is a contributing factor to the small berry crop. But we don't know that is the only reason, as you pointed out. The best way to really know about a native plant is to go to our webpage on it; in this case, you can follow this link to our webpage on Ilex verticillata (Common winterberry). From that page:

"Growing Conditions

Water Use: High
Light Requirement: Sun , Part Shade , Shade
Soil Moisture: Dry , Moist , Wet
Soil pH: Acidic (pH<6.8)
CaCO3 Tolerance: Low
Soil Description: Moist, acidic soils. Sandy, Sandy Loam Medium Loam Clay Loam, Clay
Conditions Comments: Winterberry tolerates poor drainage and is quite winter-hardy. You must have both a male and female plant to have berries. The male must be the same species as the female and bloom at the same time. Because hollies are such popular landscape plants, it may be worth the risk to plant a female and hope there is a male nearby."

Note that this plant can tolerate "sun," which we consider to be 6 hours or more of sun a day, "part shade," 2 to 6 hours of sun a day and "shade, " which is 2 hours or less of sun. We don't know anything about Ilex needing moist, boggy conditions, it just has high water needs. You should also note that it can tolerate some ordinarily pretty inhospitable soils. It does prefer acidic soils, but it can grow in clays, which many plants cannot.

From the Missouri Botanical Garden, here are articles about the cultivar 'Nana," and the cultivar 'Jim Dandy'.

In answer to your original question, we always feel that more sun prouduces more flowers and hence more berries. However, we also feel that transplanting can be very traumatic to any plant. If you want help making your decision, start by timing how long there is sun on each part of your garden you are considering. The hackberry, beneath which you have the winterberries planted now, is deciduous, so the plants will have more sun in the winter and early Spring, which might help the blooming. And don't factor in the berry-eating sparrows in making your decision; the birds can fly and they will find the berries. Bees and some butterflies are the pollinators so don't go spraying insecticides on your plants.

We always check to make sure the plant is native not only to North America but to the area in which they are being grown. This USDA Plant Profile Map shows your winterberry grows natively in Cook County, so there is a pretty good chance that your soils are suitable. Once you have measured the amount of sunlight your hollies are getting in their present position, you are the one that can make the best decision on whether to move or leave the plants where they are.