Valley Tissue Culture produces elite seed potatoes using 'in vitro' technology

A Halstad, Minnesota, family has created a business of producing early-generation potato seed for potato seed producers. The business is a two-generation effort, with numerous employees here on H-2A visas.

A couple in their 60s, and children and spouse in their 30s, who together run an in-vitro potato seed business at Halstad, Minnesota, stand near their Valley Tissue Culture signage at their office and greenhouse headquarters.
Key people at Valley Tissue Culture Inc., of Halstad, Minnesota, are, from left, co-founders Randy and Sandi Aarestad, flanked by their son, Charles Aarestad, and daughter, Alexandra “Alex” Bare, and her husband, Michael. Photo taken June 29, 2022, Halstad, Minnesota.
Mikkel Pates / Agweek
We are part of The Trust Project.

HALSTAD, Minn. — Valley Tissue Culture, Inc. is a Red River Valley business that has grown from an experimental concept in the 1980s into a multi-generational potato seed company today.

Today, Sandi Aarestad, 65, runs the business with a daughter, Alexandra “Alex” Bare, 35, and a son, Charles “Charlie,” 34. They grow and sell low-generation seed potatoes for farmers who produce seed potatoes sold to commercial growers. Other key people are Sandi’s husband and co-founder, Randy, as well as Alex’s husband, Michael Bare.

A collection of potatoes lie on a table, in various colors and flesh colors. These "gourmet" spuds are among 125 varieties Valley Tissue Culture provides seed for.
Valley Tissue Culture Inc., maintains some 125 varieties of potatoes for seed-producing customers. Potatoes come in numerous descriptions, many with “gourmet” flavors, flesh colors and some with unique nutritional attributes. Photo taken June 29, 2022, Halstad, Minnesota.
Mikkel Pates / Agweek

The Aarestad family and their crew raise seed potatoes started in test tubes in the lab, and then grow them out in greenhouses. Valley Tissues sells to 40 customers — primarily in North Dakota and Minnesota, but also in Canada, and as far as the states of Washington and Idaho.

Harvest typically runs from mid-August to mid-October. Two-thirds of the harvest is inside the greenhouse. Outside harvest is done only after the vines are dead, and the seed is no longer vulnerable to insects or pathogens.

H2A visa temporary employees from South Africa at Valley Tissue Culture harvest seed potatoes that had been grown indoors but whose vines have died and are no longer vulnerable to disease or insects. Photo taken Sept. 19, 2022, Halstad, Minnesota.
Trevor Peterson / Agweek


Rocks, lunch

Sandra “Sandi” Charles acknowledges she did not plan a career farming, especially in a sophisticated corner of agriculture. She grew up on a farm near Hancock, Minnesota. Her family raised pigs, corn, soybeans and some wheat. The girls helped with rock picking, but mostly brought lunch.

Sandi went on to study home economics at North Dakota State University, where she met her future husband, Randy Aarestad, a farmer from Hallock, Minnesota.

Sandi Aarestad prepares a gelatin/nutrient mix that will nourish young plantlets that will be grown to be being multiplied into seed potato plants.
Sandi Aarestad, longtime chief executive officer and co-founder of Valley Tissue Culture Inc., at Halstad, Minnesota, three or four times a day prepares a gelatin/nutrient mix that will nourish in-vitro potato cuttings that will be grown into seed potatoes for elite seed growers across the country. Photo taken June 29, 2022, Halstad, Minnesota.
Mikkel Pates / Agweek

Randy and his brother, Larry, then ran Aarestad Farm Products. The company produced a half-dozen certified seed potato varieties and washed potatoes from other producers from November to February. Since 1949, the Aarestads also ran Red River State Bank at Halstad.

Initially, Sandi busied herself roguing fields and driving truck and combine. The Aarestad brothers specialized in iconic Red River Valley red varieties. They bought “foundation” seed but a bacterial ring rot infestation in the 1980s was devastating, economically. Their entire production had to be thrown out.

A large greenhouse is filled with growing potato plants, and at right is a woman who co-owns the seed potato enterprise, tending the plants with a machine that provides water and nutrition.
Alexandra Bare checks the greenhouses twice a day, and uses a water-driven chemical injector, a water-soluble fertilizer, and applies it through the drip tape irrigation or through a mister. Photo taken June 29, 2022, Halstad, Minnesota.
Mikkel Pates / Agweek

About that time, Florian Lauer, a University of Minnesota potato breeder, started promoting “in vitro” tissue culture seed production. With the new test tube method, Lauer would propagate from a plantlet (cutting) — the meristem — or sprout. He’d clean the sprouts with sterile water, a diluted bleach and sterile rinse, and then grow them in a “media” — a gelatinous mix with vitamins and nutrients.

Hands dig into a peat soil mix, to find yellow, shooter marble-sized seed potatoes at the end of June that will be harveted in mid-August.
Seed potatoes, initially grown in the laboratory, are transplanted to one of 13 greenhouses at Valley Tissue Culture Inc., near Halstad, Minnesota. They grow in a peat mix, changed annually, and are harvested from mid-August to mid-October. Photo taken June 29, 2022, Halstad, Minnesota.
Mikkel Pates / Agweek

Sandi remembers Randy traveling to one of Lauer’s demonstrations at Williams, Minnesota, near Lake of the Woods County, and coming home with the exclamation:

This is the future!

‘The future!’

In 1984, the Aarestads started with four test tubes in a small greenhouse. By 1985 they’d set up a second small greenhouse. While Randy focused on the fields, Sandi, with a toddler and pregnant, did lab and greenhouse work, helped by ladies in town. They continued to expand, building new greenhouses in 1987, 1988 and 1989.


Boxes filled with container supplies are kept in any free space, an effort to prevent shortages as happened during the pandemic.
Sandi Aarestad of Valley Tissue Culture Inc., at Halstad, Minnesota, prepares a gelatin/nutrition “media” in which potato seed will be grown in the laboratory, prior to transplanting into a greenhouse and then being sold to seed potato producers. Some hallways are partially filled with stacked box materials -- an inventory the company built up to counter the supply shortages felt during the pandemic. Photo taken June 29, 2022, Halstad, Minnesota.
Mikkel Pates / Agweek

In the early 1990s, Randy and Larry split their farming enterprise. Randy primarily focused on the family’s other business interests.

Sandi ran Valley Tissue Culture day-to-day as tissue culture seed took over the industry. Seed growers paid more for seed than under the old system, yes, but their seed yields doubled. The Aarestads became known for diversity — producing seed for russets, chip potatoes and table stock varieties.

A quartet of test tubes are headed at right by the "mother" tube, from which cuttings are taken to maintain a variety in a library of about 125 varieties at Valley Tissue Culture, Inc.
Alexandra Bare, holds a test tube at right that is the “mother plant” for one of the company’s 125 varieties. The mother tube holds the plant from which cuttings were taken to make the other three test tubes, updated once a month. Photo taken June 29, 2022, Halstad, Minnesota.
Mikkel Pates / Agweek

In the mid-1990s, the U.S. Department of Agriculture deregulated (legalized for commercial sale) varieties that Monsanto had genetically engineered to resist Colorado potato beetles. Valley Tissue was the first private tissue culture company to do work for the ag-bio giant.

In 2010 they built four more greenhouses for the total of 13 they still have today.

A woman tends potato plants in a greenhouse, flanked by the large fans that pull cool air through water-fed "cool cells."
Large fans on the east end of a greenhouse pull air through a water-infused “cool cell” on the western wall, as Alexandra “Alex” Bare checks potatoes for nutrients in late June 29, 2022, at the Valley Tissue Culture of Halstad, Minnesota.
Mikkel Pates / Agweek

Seed potatoes in the greenhouses grow in rectangular trays of about 2-by-4-feet, in virgin peat mixture, watered with “drip tape” irrigation fed by well water. Alex checks growing spuds at least twice a day in person and ensures they have enough water or nutrition.

Most of the greenhouses on Valley Tissue Culture, Inc., at Halstad, Minn., are shown in the foreground, with a farm home at left.
Valley Tissue Culture, Inc., was created in the early 1980s to propagate seed potatoes from a laboratory and in a greenhouse environment, to ensure the seeds don’t carry diseases that can harm production. The company has 13 greenhouses. Photo taken Sept. 19, 2022, Halstad, Minn.
Trevor Peterson / Agweek

Every three to five years, Valley Tissue Culture must “re-skin” the greenhouses, replacing the double-layer of plastic. Greenhouses prevent any intrusion from disease when potatoes are growing to create mini-tubers.

“We try to keep everything neat around here — nothing out — because that gets picked up in the wind,” Sandi said.

Some varieties aren’t placed near each other. Many red breeds grow 60 to 80 days, while a brown-skinned frying potato might be 100 to 140 days. The plants die down naturally at the end of their life.


A corrugated cardboard-like "cool cell" at left, is at left, as a woman feels the temperature difference.
Alexandra “Alex” Bare, shows explains how water flows from a PVC pipe through a heavy-duty cardboard “cool cell.” Air pulled through the cell with fans keeps temperatures friendly to plants in a greenhouse at Valley Tissue Culture, Halstad, Minnesota. Photo taken June 29, 2022.
Mikkel Pates / Agweek

The Valley Tissue greenhouse employs a kind of air conditioning they call a “cool cell” — essentially a long PVC pipe with holes in it. The “cell” is corrugated, durable cardboard. Water trickles down through the kind of corrugated, durable cardboard. Fans on the other east side of the greenhouse, draws cool air through the cool cell, normally keeping the greenhouse in the mid-70s

Close, yet far

The Aarestad family includes three daughters and a son, born in four succeeding years. The eldest is Cristina, born in 1985; Danielle, 1986; Alexandra, 1987, and Charles, 1988. Sandi strove to get all four out in the greenhouse to work in the summers. Alex worked in Valley Tissue in high school and college.

Small, mini-tuber russet seed potatoes grow in a test tube at Valley Tissue Culture, Inc., at Halstad, Minnesota.
A mini-tuber russet potato variety grows in a test tube at Valley Tissue Culture, Halstad, Minnesota, a company that produces in-vitro disease-free seeds for elite seed potato producers, who sell subsequent generations to commercial growers across the country. Photo taken June 29, 2022.
Mikkel Pates / Agweek

All four graduated from Oak Grove Lutheran School in Fargo, North Dakota. All took education and careers, but eventually returned to live and raise children within five miles of home, all with careers nearby, relating to family businesses and agriculture. There are 13 grandchildren, and another on the way.

    A plastic container filled with disease-free cuttings potato leaf parts and terminal stems that eventually will become plants that grow seed potatoes.
    Potato node (leaf) and tips, cut by six employees – women from South African H2A temporary visas – are placed into containers the Valley Tissue Culture, Inc. “Terminal” cuttings, meaning the top of the plants, grow faster than a ‘node’ cutting,” which is further down the plant, but are needed to get enough to multiply to sell to potato seed growers. Photo taken June 29, 2022, Halstad, Minn.
    Mikkel Pates / Agweek

    Alex’s world

    A woman stands next to a  "maintenance bank" of sets of four test tubes with potato varieties that are maintained in a room full of white shelves, every few weeks.
    Alexandra Bare stands next to a shelf that holds a “maintenance bank” for 125 varieties that can be supplied by Valley Tissue Culture of Halstad, Minnesota. Photo taken June 29, 2022.
    Mikkel Pates / Agweek

    It turned out, Alex was a natural fit at Valley Tissue.

    She graduated high school in 2006. She went on for a biology degree at the College of St. Scholastica in Duluth, Minnesota. She briefly pondered a career in health care. In 2010, while considering graduate school options, she came home to help Sandi. Three years later, she knew she’d stay. In 2014, she married Michael Bare, who she’d met earlier through track and field.

    Several women in hairnets and masks sit at laboratory hoods, working on trimming potato vine nodules and meristems.
    Valley Tissue Culture, of Halstad, Minnesota, annually hires seven H2A temporary agriculture employees, who work from January to November. Part of the work is taking cuttings from potato plants to multiply in-vitro into potato plants that are then transplanted to 13 greenhouses, and later harvested to sell to elite seed potato growers. Photo taken June 29, 2022.
    Mikkel Pates /Agweek

    At Valley Tissue, Alex and her mother grappled with finding workers who could handle the long hours, and keep all the “detail work” straight. Eventually they started using the federal H2A temporary visa program to bring in employees from South America. Valley Tissue started with two, then four and now hire seven a year.

    A woman in white laboratory coat, hair net and mask, cuts up pieces of a potato plant for propagation.
    A temporary employee from South Africa, in the U.S. on an H2A visa, takes cuttings from potato varieties to be grown in the laboratory and then transplanted into a greenhouse, to be grown and sold to potato seed producers. Photo taken June 29, 2022, Halstad, Minnesota.
    Mikkel Pates / Agweek

    Alex does all the hiring. She works with a Tulsa, Oklahoma, agent and two agents in South Africa. Alex views a video that comes with each candidate. She spends time online, talking with each potential candidate, learning about their previous work experience and goals.The South Africans come in late January and stay through November 15. Most are white women in their 20s and 30s. Some have a little farm experience. Valley Tissue hires only people who speak English.

    Valley Tissue pays for the worker’s visa, their air travel, housing, local work transportation, and competitive wage. (North Dakota’s “adverse effect wage rate in North Dakota is $16.47 per hour, higher than Minnesota’s $15.37 per hour, but Minnesota businesses must pay overtime.) The U.S. farm pay is about two or three times what they can make back home in a market where they say the indigenous workers often get preference.

    A stem of a potato plant from a test tube is trimmed of leaf nodes, left, and terminal buds to multiply into greenhouse plantings to meet customer orders.
    An employee takes cuttings from potato stems as thin as toothpicks, in laboratory work at Valley Tissue Culture at Halstad, Minnesota. The tool at left holds a leaf “node” which will grow into a potato, and the one at right holds the “terminal” tip which is the strongest part of the plant for growing a new potato. Photo taken June 29, 2022.
    Mikkel Pates / Agweek

    Mothers, clones

    Public and private potato breeders provide send clones of new potato varieties in a clean test tube. Valley Tissue gets “mother plants” tested ensure they don’t have any of the 16 pathogens she needs to be clear of to be certified to sell “pre-nuclear” seed to farmers.

    Customers declare their needs for potato seed volume 18-months in advance. Most varieties are protected under the U.S. Plant Variety Protection Act (PVPA), which allows the developer to collect royalties. “Pre-nuclear status is the top of the elite of the elite in the ‘generation system,’” Sandi said. The goal is to eliminate viruses and viroids that mutate.

    • Valley Tissue takes orders for “ seed, and pay by the pound in increments often ranging from 50 pounds to 300 pounds, which plants roughly one acre. Valley Tissue sells seed in small, medium and large seed size.
    • The seed farmer plants this as  “G1” (generation-one) or “Field G1.”
    • Seed farmers plant G2 the next year.
    • In years 4 and 5, the seed producer sells G3 and G4 to “increase growers” or  commercial farmers who want lower generation seed.
    • G5 potatoes go to “wash plants,” where processors mostly are concerned that
      potatoes are free of bacterial issues.

    Sandi has always been wary about making the business too large, concerned about keeping it under sufficient control.
    As it is today, Alex said the only “down time” is in November through mid-January, which is focused on maintenance, buying supplies and organizing, and making tags for seed going out.

    Sandi sees opportunities in the business, especially in organic production.

    “There is no organic, high-quality seed out there, for potatoes,” Sandi observed.

    Organic producers — because they’re a small industry — have ways of skirting certain U.S. Department of Agriculture laws regarding seed potatoes.

    “If Randy and I were younger, we’d be farming and having an organic seed farm — commercial — for selling seed to organic producers,” Sandi said.

    A lineup of greenhouses are flanked by a yellowing Red River Valley soybean field on the outskirts of Halstad, Minnesota.
    Valley Tissue Culture Inc., grew with demand for disease-free seed potatoes. Greenhouses were built from the early 1980s to 2010. Photo taken Sept. 19, 2022, Halstad, Minnesota.
    Trevor Peterson / Agweek

    But at ages 65 and 68, Sandi and Randy are happy to be transitioning to the “kids,” whose plates are already full. Alex and her brother, Charlie, are becoming the new owners.

    Alex is enthused about the future.

    ”I think people will always eat potatoes,” she said.

    There are satisfactions in meeting customer needs, and personal satisfactions.

    “I hope that my kids — all my kids, and especially girls — will look at me someday, and think, ‘Wow, I want to be like mom — hard-working agriculture professional who wants to get something done and make a difference.’”

    Mikkel Pates is an agricultural journalist, creating print, online and television stories for Agweek magazine and Agweek TV.
    What To Read Next
    Shoppers of a bridal and tuxedo retailer were met with confusion Wednesday as the long-running store closed suddenly.
    Owner and designer Daniel Johnson Jr. closed his Levels store in Rochester’s Apache Mall as well as his shop in the Mall of America on Jan. 31. However, both will reopen in new spaces in March.
    You voted. We tallied. Now we’re going to eat at every single one. It’s our 24th annual Best Restaurants results.
    For years Rochester lacked authentic Cuban and Jamaican Food. Francisco's broke into the restaurant scene eight years ago but has finally settled in as a sit-down restaurant across from Saint Marys.