Concerns that a recession is coming have not been good news for financial markets. The S&P 500 index has declined 16% so far in 2022, yet the index's dividend yield is still only a meager 1.6%. 

This simply isn't going to be enough to please income investors. This raises the question: What can yield-oriented investors do? Real estate investment trusts (REITs) can be great investment vehicles to consider. This is because they avoid corporate taxation as long as they distribute at least 90% of taxable income to shareholders. 

Here are two fast-growing REITs with 4%-plus dividend yields for income investors to think about adding to their portfolios. 

A businessperson prepares a report.

Image source: Getty Images.

1. Innovative Industrial Properties: The leader of the cannabis real estate industry

Public policy often lags behind public opinion. This is arguably no more abundantly clear than when it comes to cannabis. In support of this point, 93% of Americans support patient access to medical-use cannabis, and a full two-thirds (68%) support full legalization of cannabis. Yet, the drug remains federally illegal.

As more states legalize cannabis, the U.S. regulated cannabis industry is expected to nearly double from $24 billion in 2020 to $46 billion by 2026. Few companies will benefit from this unstoppable trend as much as the cannabis REIT known as Innovative Industrial Properties (IIPR 1.22%)

With 111 properties in 19 states worth $2.6 billion, Innovative Industrial is the most established cannabis REIT. Because it is the most well-known and trusted name in the industry, it's no surprise that the company has made $368.6 million in new investments through the first nine months of this year. This has resulted in double-digit percentage rent revenue and adjusted funds from operations (AFFO) per share growth so far in 2022. 

Innovative Industrial's 6.4% dividend yield is quadruple the S&P 500 index's 1.6% yield. And with the dividend payout ratio coming in at 82.2% in its most recent quarter, there is an adequate margin of safety to endure tenant defaults like that of Kings Garden. 

The REIT may have to deal with tenant defaults from time to time in the years ahead. But with a trailing-12-month (TTM) price-to-AFFO-per-share ratio of 13.5, this risk is arguably already priced into the stock. Given Innovative Industrial's robust growth prospects, a valuation multiple in the low teens makes it a no-brainer buy for income investors. 

2. Crown Castle International: A bet on growing mobile data consumption

In developed economies such as the U.S., you will see people with smartphones around practically every corner. And the infrastructure of the pure-play U.S. cell tower REIT named Crown Castle International (CCI -0.90%) makes it possible for Americans to use their phones every day to browse the web, check emails, and shop online. 

To get an idea of just how big Crown Castle is, the company owns a staggering 40,000-plus cell towers, 115,000 small cells, and 85,000 route miles of fiber optic cable. Major telecom companies such as Verizon (VZ 0.79%) lease these cell towers and small cells to provide mobile data to customers. Given that U.S. average monthly mobile data consumption by individuals is expected to surge from 21.9 gigabytes (GB) in 2022 to 54.2 GB by 2027, more cell towers, small cells, and fiber will need to be constructed in the future.

Along with annual lease escalators on existing infrastructure, this should lead to 7% to 8% annual dividend growth in the years to come. Paired with a 4.5% dividend yield, this is an excellent combination of starting income and growth potential. And with the dividend payout ratio set to come in at 81.2% in 2022, the dividend is reasonably well-covered. 

The cherry on top that makes Crown Castle a buy for income investors is that the stock is trading at a forward price-to-AFFO-per-share ratio of about 19 at the current share price of about $143. That's hardly an expensive valuation for the high-single-digit annual growth that Crown Castle can offer its shareholders.