Growth in retail sales in Maryland was less than half the national average last year, with sales of big ticket durable goods such as cars and washing machines suffering the most, according to a recent Commerce Department report.

The government reported that retail sales increased 2.49 percent in Maryland last year, compared with a 5.07 percent national growth rate. The slower pace reflects a slowing in consumer spending and home building that has continued into the first half of 1990, the government said. A decline in sales of durable goods, especially cars, was responsible for the slower growth in overall retail sales last year. Sales of durable goods dropped 2.98 percent; by comparison, sales of nondurables were up 6.53 percent.

However, Tom Saquella, president of the Maryland Retail Merchants Association, said weak durable goods sales masked an otherwise healthy retail outlook. "Where we've really suffered is durables. O other than that, we really didn't have a bad year," he said.

Sales dipped 0.19 percent in Maryland in the first six months of 1989 and rebounded strongly rising 5.05 percent in the second half. That compares with a national increase of 2.02 percent in the first half and 4.85 percent in the second half.