No, contributions can no longer be made once the beneficiary reaches the age of 18.

Once the beneficiary reaches age 18, he or she can take control of the account. Funds must be used by the time the beneficiary turns 30 years old or transferred to a younger sibling.  The funds can also be rolled into a 529 plan. 529s have no age limit.

Note: special considerations are given to disabled and special needs beneficiaries.  The contributions and age limitations are lifted for these individuals in most cases.