When Emma Cunniff, 25, started her own farm three years ago, she got a crucial infusion of capital by creating a community-supported agriculture program, or CSA. It let backers pay up front for shares of produce through spring, summer, and fall - and supplied Cunniff with money to buy seeds and tractors, and to eventually expand her Kneehigh Farm in Pottstown from two acres to seven.

That's how it's worked ever since the CSA movement began 30 years ago.

Now, though, small farmers like Cunniff are finding themselves in competition with a slew of subscription-based food vendors, from meal-kit boxes like Blue Apron to mail-order produce boxes like Farmbox Direct to aggregators who mix local produce with stuff from Florida or Mexico.

For consumers, it means more choice than ever, including options to customize shares or pay à la carte, or subscribe to fun offerings like ice cream or beer. But it also means those who care about supporting local farmers have to pay more attention to the fine print.

Cunniff, who delivers to Chester County, Philadelphia, and Swarthmore (831-331-7086, kneehighfarm.com), said it's changing the business.

"I've noticed so many cooperative-buying clubs; they're not CSAs, but they have adopted that title because it's really hot and sexy right now. Some of their farms are up to 250 miles away. That's not local agriculture," she said. "They're doing great things to get fresh produce into cities, but it definitely hurts small CSA farmers."

She's had to find ways to keep up, such as offering a swap box at each pickup site and partnering with other farmers to offer add-ons to her CSA: fruit, gourmet mushrooms, and eggs. Still, she said: "It feels impossible to compete sometimes. I can't customize your share. And I can't do week-to-week payments. I need the money up front."

Mary Seton Corboy, founder of Greensgrow Farms - which runs a 14-year-old CSA with pickup sites around the city (215-427-2780, greensgrow.org) - said she'd been contemplating "the purity of CSAs" lately.

Greensgrow, a nonprofit urban farm in Kensington, was one of the first aggregated CSAs, meaning it gets vegetables, fruit, eggs, and dairy from numerous farms. Corboy said that when she started, "some people felt it was exploiting the original concept. But what's the point of a CSA if not to get local fresh food into the city and support regional growers?"

She often contracts with farms in the fall for the next season and pays in advance to cover up-front costs. With about 800 members, Greensgrow is the largest account some of its farmers have. But Corboy worries some consumers have forgotten the meaning of a CSA - including that it comes with shared risk if crops fail.

"I wouldn't be surprised to see a ShopRite CSA," she wrote in a note to members recently.

After all, the boutique mini-chain Green Aisle Grocery (267-687-2398, greenaislegrocery.com) started a CSA in January, offering boxes of fruits, vegetables, meat, eggs, yogurt, and treats such as honey, hummus, or pickles.

Co-owner Adam Erace said his CSA was a fit for those who find a standard farm share overwhelming. "We saw a need for a hybrid," he said. Besides, small businesses, just like small farms, benefit from creating predictable demand in slower seasons.

There's clearly demand.

Philly Foodworks, a two-year-old company that lets shoppers customize shares of produce, dairy, meat, and more each week - and pay either up front or à la carte - already has about 800 members.

Cofounder Dylan Baird said it evolved from his own urban farming experience. "We ran a traditional CSA, and heard people's frustrations with it."

He buys mostly from farms within 150 miles and uses advance payments to give out loans, totaling $40,000 in 2015. That was enough to buy two farmers greenhouses and give others seed money. Baird said Philly Foodworks (215-221-6245, phillyfoodworks.com) has, for example, revolutionized business for Amish farmer Reuben Ridhil.

But it's not all local. He does sometimes buy from distributors or order Florida citrus to make it through the winter.

"What we're doing is blurring the lines [between a CSA and other grocery services]," he said, "and I think that's what's powerful about it."

smelamed@phillynews.com

215-854-5053

@samanthamelamed

10 CSAs You Wouldn't Expect

There are more - and more specific - CSA options than ever. Shares are limited, so order early.

Farmstand share: Germantown Kitchen Garden invites members to pay $75 to $625, and then use that account to shop for produce and live plants all summer. Farmer Amanda Staples said the model provides flexibility for her and her customers: "The thing that's important to me is the 'why' of it, that the farmer and the customer have a partnership." 610-505-4881, germantownkitchengarden.com

Meat: Ironstone Creamery & Farm offers several pickup sites for whole chickens and five-pound pork shares. It's a way for those committed to nose-to-tail eating to put their money where their mouths are, farmer Joe Albano said. 610-952-2749, ironstonecreamery.com

Flowers: Jig-Bee, in Kensington, offers a loose-flower subscription service and a bouquet CSA, starting in July. 267-777-9636, jig-bee.com

Bread: Chris DiPiazza of Mighty Bread Co. sells his naturally leavened, slow-fermented bread via subscription. The share includes weekly loaves like rustic olive or rosemary peppercorn, and a monthly treat like local jam. mightybreadco.com

Housewares: Heidi Barr, the maker behind the Kitchen Garden Series of aprons, tea towels, and market bags, borrowed the CSA model for CSArtisans, a quarterly subscription box. The fall share is an apron by Barr, a porcelain tart plate from Heirloom Home Studios, and local artisanal nut butters. A portion of sales goes to local nonprofit farms. TheKitchenGardenSeries.com

Beer, pastries, jam: The aggregated CSA West Philly Foods offers pickup spots for a range of shares available as add-ons or alone. Buy a Dock Street beer share, a Spruce Hill Preserves jam share, or a Fakira pastry share. westphillyfoods.com

Cheese: Yellow Springs Farm in Chester Springs produces up to 30 unique cheeses each season, from an herbed chèvre to a cheese infused with fresh berries, for a 13-week cheese CSA. 610-827-2014, yellowspringsfarm.com

Ice cream: Weckerly's fans can sign up for a mix of pints and ice cream sandwiches, either as an add-on to a local CSA or as a stand-alone subscription. It provides access to short-lived seasonal flavors, such as honeysuckle ice cream. 215-882-9958, weckerlys.squarespace.com