You may have heard the pithy investing mantra to “sell in May and go away.” Because stocks tend to underperform during the summer months, the idea is to sit them out and wait for better opportunities in the fall. I don’t invest that way. I prefer to put my money to work at regular intervals all the time.

Buying dividend growth stocks is one of the best ways to do that. Studies show dividend stocks outperform non-payers by a wide margin during almost all periods. They also show that stocks that initiate dividends and then raise them are the best stocks to buy overall.

I like stocks that regularly raise their payout by a healthy margin but also have the financial wherewithal to support those payments. So while I look for dividend growth, I also seek out stocks that have excellent free cash flow (FCF) growth as well.

Free cash flow is the money that’s left over after a business pays its bills. It can only use that money for certain things, such as paying a dividend, buying back stock, making acquisitions or investing in the business. Healthy FCF growth is a key consideration in my investment decisions.

The seven stocks below all offer both of those conditions in spades. Some I own and some are on my watchlist. All of them, though, are worth considering for your own portfolio.

Chubb (CB)

If it’s good enough for Warren Buffett it’s good enough for me. Property and casualty insurer Chubb (NYSE:CB) is the hidden stock Buffett bought that he didn’t want anyone to know about. Regulators give him and other big bucks investors special privileges to buy stock without telling anyone so they can get the best price before everyone piles in.

Chubb stock was trading around $252 per share before it was revealed Buffett bought $6.7 billion worth of the insurer. That was enough to land it as his ninth largest holding although it accounts for just 2% of the Berkshire Hathaway (NYSE:BRK-A, BRK-B) portfolio.

The insurer’s dividend history is actually not quite what I look for though that may be changing. Over the past decade, Chubb has raised its dividend at a compounded annual growth rate (CAGR) of 2.2% and over the last five years it is only slightly better at 4.1%. What I do like is Chubb has expanded FCF over the past 10 years by an eye-opening 13% CAGR. It also just announced a dividend increase that jumped 6% letting the payout yield a respectable 1.4% annually.

Maybe because it has so much FCF available now it will start focusing on increasing its dividend more. It is why the insurance company may deserve a spot in your portfolio.

Realty Income (O)

Any dividend growth investor worth their salt is familiar with real estate investment trust (REIT) Realty Income (NYSE:O). The REIT pioneered the monthly dividend payment and it has not disappointed. Since listing on the NYSE in 1994, Realty Income has made 647 consecutive monthly dividend payments. More impressive, it has raised the payout for 107 straight quarters, including its more recent increase where it raised the dividend 2.1% to 26.25 cents per share.

Although the increase might seem on the low side, remember, this happens every three months in perpetuity. This is about as solid of a dividend growth stock as you can find. As a REIT though, you don’t want to look at its FCF but rather its adjusted funds from operation (AFFO), a metric similar to FCF for REITs. For Realty Income, its AFFO payout ratio stands at just under 75%. While that may look dangerously high, recall REITs are required to pay out 90% or more of their profits as dividends. It means Realty Income’s dividend is both safe and sustainable.

REITs like Realty Income have been hurt by the high interest rate environment we’re in. The stock is down 12% over the past year. It is comforting to know, though, you can get paid a healthy yield (5.9% annually) while you wait for the Federal Reserve to cut rates again and for Realty Income to resume its growth trajectory.

UnitedHealth Group (UNH)

Another dividend-paying insurance stock to buy is UnitedHealth Group (NYSE:UNH). This one, as its name implies, is a health insurer. Because healthcare is a critical expense for people and one they typically won’t or can’t go without no matter market conditions, it makes UnitedHealth an all-weather stock.

The insurer has used its premier positioning to reward shareholders. UnitedHealth has grown its dividend at an 18% CAGR for the last decade while increasing it by almost 13% over the last five years. FCF has widened at an equally impressive CAGR of 16% for the past 10 years. Although its FCF payout ratio has been climbing steadily for several years running, it still sits at an extremely low 26%, meaning the insurer’s dividend is sound.

The company has been expanding its outlook and reach through acquisitions, especially in home healthcare. It previously acquired LCH Group and is trying to acquiring Amedisys (NASDAQ:AMED). The purchase, however, is being scrutinized by regulators and may cause the stock to sumble if denied. But UnitedHealth doesn’t need the care facility to thrive so any weakness in the stock should be seen as a buying opportunity.

Parker-Hannifin (PH)

Parker-Hannifin (NYSE:PH) has been around since 1917 and has been paying dividends for almost just as long. It has made 295 consecutive quarterly dividend payments, or nearly 74 years worth. Moreover, the motion control systems manufacturer has raised the dividend for 67 straight years making it a Dividend King.

It’s often the case that such stalwart dividend stocks don’t exhibit the sort of growth you want to see in their payout. These are large, mature businesses that can’t increase the dividend the same as younger companies. That doesn’t apply to Parker-Hannifin though. It has a 12.6% CAGR for the past 10 years and a better-than 13% CAGR over the last five. Equally impressive is Parker-Hannifin growing FCF at double-digit rates over those same time frames as well.

Investors also benefit from capital appreciation. In just the past year the motion control specialist stock is up 63% and offers a 10-year total return of 400%. That’s well ahead of the S&P 500’s 228% return. For a venerable industrial stock like Parker-Hannifin, that’s an impressive result.

Apple (AAPL)

Apple (NASDAQ:AAPL) continues to surprise Wall Street and the stock market. When many were leaving it for dead due to slowing sales in China, the tech giant put together back-to-back months of growth. Bloomberg reports the iPhone maker saw 52% shipment growth in April following a 12% gain in March. Shipments had been down in the first two months of the year, lending credence to the analysts’ concerns.

However, CEO Tim Cook recently flew to China to meet with its partners in the country and smooth over any rough spots in their relationship. It apparently worked as sales are accelerating now.

Shareholders were also heartened by Apple’s massive $110 billion stock buyback program it announced. At the end of the first quarter the consumer electronics company had $67 billion in cash and equivalents available to it on its balance sheet.

Many dividend stock investors dismiss Apple out of hand as an investment because of its paltry 0.5% dividend yield. That would be a mistake. While it has grown its payment at an 8% CAGR over the last decade, its FCF payout ratio is just a super low 15%. It suggests dividends are not a priority for the tech star. What has it been doing with its FCF? Stock buybacks like the massive program just mentioned. Apple prefers to reduce its share count, which helps bolster and grow earnings and revenue per share. That even occurred last year when revenue fell!

Because Apple does throw off a lot of cash, the dividend will always receive attention even if it is not the top priority.

Zoetis (ZTS)

Zoetis (NYSE:ZTS) is one of the world’s largest animal health providers offering a portfolio of therapies, vaccines, diagnostics and technologies in use in over 100 countries. It is a recession-resistant business because pet owners tend to ignore family pet health issues even less than their own no matter the economic conditions.

According to the American Pet Products Association, pet owners spent $147 billion on their four-legged friends last year, 7.5% more than the year before. They are expected to spend another $150.6 billion this year. Of that amount, fully 26% was spent on vet care and products. It’s a very profitable business for Zoetis, which generates gross margins north of 80% in the U.S. and around 70% internationally.

Zoetis has produced near 500% total returns for investors over the past decade, double the broad market index. It has also grown its dividend at a 20% CAGR over that time frame. In the last five years, it has increased 21% annually with a 23% FCF CAGR.

Visa (V)

Leading payments processor Visa (NYSE:V) is the last dividend stock to buy on this list — though definitely not the least. There are some 4.3 billion Visa cards in circulation and they generated $14.5 trillion in total payments and cash volume for its full fiscal year. 

Visa’s dividend yields less than 1% annually, which might dissuade some investors from buying. Yet the payments processor has a hefty record of increasing the payout every year. In 2013, Visa paid about 35 cents per share. After hiking the dividend last October, it now pays $2.08 per share, a 20% CAGR. As FCF grows at a 22% CAGR and the FCF payout ratio is a miniscule 19%, Visa has plenty of gas left in the tank for further generous dividend increases in the future.

A recession could impede Visa’s growth as people cut back on their spending habits. The move to a more digital payments environment, however, means the payments processor has more opportunities to capture transactions. As recessions tend to be measured in months but bull markets go on for years, any slowdown will be temporary and a buying opportunity.

On the date of publication, Rich Duprey held a LONG position in O stock. The opinions expressed in this article are those of the writer, subject to the InvestorPlace.com Publishing Guidelines.