The following information came from Ernst & Barbour (1972) and Klemens (1993):
Reproductive maturation for females and males differs with latitude and the length of the growing season. Specific information for painted turtles in Connecticut was not available. However, Ernst & Barbour (1972) describe the following trends for painted turtles in Pennsylvania: 1) females are often mature by their 5th year, with mating occurring the next spring; and 2) males are usually reproductively capable by their 4th year, with mating occurring the next spring.
Spermatogenesis begins in March, peaking in July and August. The ovarian cycle begins in July or August, finishing in October. Ovulation, however, does not occur until the following spring.
Courtship and mating begins in March, lasting through June and sometimes through early fall. Courtship consist of three stages: 1) the initial chase where a male pursues a female; 2) repeated stroking where the male strokes the female's head and neck with his foreclaws and the female reciprocates by stroking his forelimbs; 3) copulation where the female rests at the bottom of the pond and is mounted by the male.
The females nest from late May until mid-July. Nesting can occur in the day or the evening. Rainy days are associated with increased nesting activity. The vase-shaped nests are dug in loamy or sandy soil. The eggs are elliptical in shape and white in color. There is both intra and inter-species variation in the number of eggs that are laid per clutch. Ranges in egg numbers for the different species are as follows:
C. picta picta: 2-11
C. picta marginata: 3-10
C. picta dorsalis: 2-7
C. picta bellii: 4-20.
The eggs incubate for 72-80 days. Hatching occurs from August through September. Hatchlings do not always emerge immediately from the nest, however. After hatching, hatchlings can overwinter in the nest, emerging from the nest the following spring. The hatchlings are able to survive periods of subzero temperatures through physiological mechanisms preventing freezing of extracellular fluids and toleration of freezing if it does occur (Packard et al. 1999a; Packard et al. 1999b)
Eastern painted turtle hatchlings
(Photo from Nova Scotia Museum of Natural History website)