The Growth Fund of Washington, which will invest in the stocks of about 20 Washington-area companies, received clearance to open for business yesterday with indications that area investors will put in almost $30 million.

The fund, a creation of Johnston, Lemon & Co., a regional Washington brokerage house, raised the $30 million in five weeks during June and early July, according to Harry J. Lister, fund president. Until the fund received final approval yesterday from the Securities and Exchange Commission, it was barred from accepting money but was permitted to take "indications of interest" from investors.

Although Johnston, Lemon had the help of 25 area brokerage houses in selling the fund, Johnston, Lemon brokers took in more than half of the $30 million, Lister said. Other major players included A. G. Edwards, Dean Witter, Thomson McKinnon and Smith Barney. Indications of interest came from between 4,000 and 5,000 investors, including some institutions, said Lister.

Lister said he was surprised with the pace of the sales. "I thought it would take until the end of the year to get to where we are today," he said.

The Johnston, Lemon fund has been competing with another Washington-based fund, the Washington Area Growth Fund (WAG), sponsored by the Calvert Fund, a subsidiary of Acacia Mutual Life Insurance Co. The WAG fund opened on June 3 with $1 million invested by Acacia. It has since taken in another $1.8 million for a total of $2.8 million. Calvert has the support of 40 area brokerage houses. The WAG fund, which opened at $15 a share, was selling at $15.48 yesterday.

Underlying the drive to create the new funds is growing evidence that the Baltimore-Washington-Richmond region is home to many public companies whose stocks have outperformed the market. The Johnston, Lemon index of 30 area stocks has risen since 1980 by 364.6 percent. During the same period, the Standard & Poor's 500 was up 70.1 percent and the Dow Jones industrial average up 55.5 percent. During the first six months of this year, the index was up 30.1 percent, compared with 14.7 percent for the S&P 500 and 10.2 percent for the DJIA.

The WAG fund has invested its money thus far in 22 stocks. They are: Martin Marietta, Marriott, Giant Food, Hechinger, The Washington Post, Pepco, USAir, PHH Group, Atlantic Research, McCormick & Co., James River, Overnite Transportation, Radiation Systems, Vie de France, Universal Leaf, Best Products, Circuit City, Entre' Computer, Maryland National Corp., Robertshaw Controls, Student Loan Marketing Association and General Physics.

Investment services for the Johnston, Lemon fund will be provided by Geico Investment Services, a subsidiary of Geico Corp. of Washington, which sells auto and homeowners insurance. Geico Investment Services already runs a preferred stock fund and a money-market fund.

Richard A. Ollen, president of Geico's two funds, is chairman of the Growth Fund of Washington, and Billy N. Joyner, vice president of the Geico funds, is its vice president. Joyner will oversee stock purchases for the Growth Fund. The Geico officials said it would take them about three months to get the nearly $30 million of Growth Fund money invested.

Working from a universe of about 50 area stocks with good track records, Joyner is expected to buy about 20 stocks for the fund. Joyner described his investment approach as "relatively conservative" and said he would emphasize companies that had "demonstrated their ability to survive for a few years."

Joyner acknowledged that, with many Washington-area stocks at all-time highs, some of the stocks looked "pretty pricey," but said the price-earnings ratios did not seem to be out of line.

Joyner said he did not think the fund's relatively large purchases would produce a major movement in the stock prices of the local and regional companies. He noted that many of the companies are quite large, and thus relatively immune to the impact of block purchases. "We're going to try to avoid moving the market," he said.

A third regional fund is the Southeastern Fund, sponsored by Wheat, First Securities Inc. of Richmond. That fund covers a universe of 365 companies in a 13-state region. It attracted $18.5 million when it first opened for business in April. The fund is now up to $35 million, and its share price, which began at $10, was quoted yesterday at $10.84. Wheat, First also has attracted more than $20 million in individual corporate accounts, which are being invested according to a similar philosophy of finding undervalued stocks, said Huntley G. Davenport, president of Wheat Investment Advisors.

The Southeastern Fund is invested in the following stocks:

Chesapeake Corp., Exposaic Industries, Nucor Corp., Reynolds Metals, AFG Industries, Ryland Group, Bruno's Inc., Marriott Corp., Pantry Pride, Aaron Rents, Heilig Meyers, Universal Furniture, A. L. Williams Corp., American Security, Dominion Bankshares, First Virginia Banks, Riggs National Bank, Suburban Bancorp, HBO & Co., System Associates, Figgie International, Fuqua Industries, Kinder-Care Learning, Best Products, Circuit City, Hechinger, Atlantic Research, BDM International, Intelligent Systems, Atlantic Southeast Airlines, CSX Corp., Carolina Freight, Overnite Transportation, Piedmont Aviation and USAir.