A Feb. 10, 2012 photo shows Matthew Huron, owner of two medical marijuana dispensaries and an edible marijuana company in Denver, examining a marijuana plant in his grow house. Medical marijuana is legal in 17 states, but the industry has a decidedly black-market aspect — it’s mostly cash-only. That’s because banks won’t touch pot money. (AP Photo/Ed Andrieski)

They’re scrambling for space to grow marijuana in Denver.

The demand is so great that warehouse space is renting for four times the price it fetched before marijuana sales began in Colorado, the Denver Post reports.

“Commercial real estate tracker Xceligent Inc. estimates that marijuana cultivation and manufacturing facilities in the city occupy about 4.5 million square feet — the equivalent of 78 football fields.

This industry has come on so fast that initially I was uneasy — it seemed like a fad,” said Brad Calbert, president of the Colliers International brokerage in Denver. “But what’s making it sustainable is supply, demand and capital. Supply is deficient, demand is excessive, and capital is abundant.”

But recreational marijuana sales brought in only $2 million in tax revenue in January, according the figures from the state’s Department of Revenue.

That represents about $14 million worth of pot, sold from about 59 businesses.

According to the Washington Post’s Niraj Chokshi:

When compared to expectations for the first six months of the year, January sales appear discouraging. If they hold for the remainder of the fiscal year, the state will see about $21 million in revenue. A mid-2013 fiscal analysis of the proposal that became the law, however, foresaw an additional $33.5 million in revenue generated in the first six months of the year. An estimate last month from Gov. John Hickenlooper’s (D) budget office predicted revenues of about $35.2 million.

The new tax figures are the first official accounting of pot sales since they began on Jan. 1 under a new Colorado law enacted in 2012.

The state of Washington has also legalized marijuana sales but legal retailing hasn’t started up there yet. There are numerous reports of pot being sold via Craigslist and other sites, however, with customers ordering it up as if it were pizza.

Washington issued its first legal marijuana growing and processing license last week, according to the Associated Press.

It was issued to Sean Green, who has previously operated medical marijuana dispensaries in Spokane as well as the Seattle suburb of Shoreline.

Green is the chief executive of Spokane’s Kouchlock Productions.

The state is set to issue retail licenses later this spring, with sales expected to begin in June or July.