At 79, the matriarch of the Missoni clan, Rosita Missoni, is a force to be reckoned with.

Though she stepped down in 1997 as head of the iconic knitwear line that she started with her husband Ottavio (Tai) over half a century ago, placing her daughter Angela at the helm, she couldn't stay idle for long.

In 2004, she launched the Missoni Home collection, and in 2009 she oversaw the opening of the first Hotel Missoni, in Edinburgh. A second property, in Kuwait, opens in March, and she has three more luxury boutique hotels—in Oman, Brazil and Turkey—in the works.

Ms. Missoni is responsible for designing the interiors of each, outfitted with furniture by Eero Saarinen, Marcel Wanders and Arne Jacobsen, and featuring the line's dizzying zig-zags, stripes and flowers throughout, mostly done in black and white but with bursts of bright pinks, teals and purples.

"I cannot stay away from color!" she said. After all these years, her eye is as meticulous as ever (for a Missoni fashion show in 1967, she famously removed the models' bras because she felt they clashed with the color of the dresses), and she's still willing to do anything in the name of good design.

In Edinburgh, for example, the doormen sport Missoni-print kilts. Here, Ms. Missoni offers her perspective on everything from the perfect lightweight chair to her favorite smell.

I realized I had a knack for interior 
design when I was a child. My favorite game was to create a house or living room in the heath forest of my village, Golasecca.

I would never have a decorator do my house, though I have many friends who are decorators, whom I respect. I think people little by little should find their own way, then ask a decorator for help, but not give your project to somebody who doesn't know how you live, what your habits are. A house must have the personality of the people who live in it.

If you're going to invest in one big piece for the home, it should be an extremely comfortable, well-designed couch; a huge mirror; or a funny-shaped, colorful rug to light up a forgotten corner.

In a hotel, I want to be surrounded by nice and comfortable things. For instance, in my hotels, I wanted to have very comfortable dining chairs that are easy to move. I hate when you are stuck in your chair. So I chose the same chairs I have in my homes, Hans Wegner's Wishbone Chair. In my main home, right outside of Milan, I have cherry wood, and in Sardinia we have oak. They last forever. My grandchildren—they are giants—like to stretch their legs out on the chairs, and they haven't been able to break them after 15 years!

The most wonderful house is La Maison Picassiette in Chartres, which was done entirely by this crazy man who decorated every surface with small fragments of ceramic tiles. It's very full of patterns. I took my granddaughter Margherita there when she was 14.

On the same day, I took her to visit Villa Savoye by Le Corbusier—a very modern house, with big windows, lots of light—so she could see the opposite sort of house. These are the two spectrums of my taste.

My favorite smell is a kind of bush called Cestrum nocturnum. It grows tiny insignificant flowers, but they open at sunset and smell all the night. It's incense and honey mixed—it's fantastic.

Right now I'm inspired by an outsider art museum that just opened in London called the Museum of Everything. It's run by Peter Blake and James Brett. It's a place that I like to get lost in.

My favorite store in the world is Rossana Orlandi in Milan. It's a fascinating space in an old building of an abandoned factory. It sells arts and crafts and fashion and hosts the best Milanese parties.

My guilty pleasures are crossword puzzles, wine and food.

As a housewarming gift, I bring a basket of fresh eggs from my chicken house with herbs and flowers from my garden.

The most treasured item in my home is a coffee table painted by my granddaughters, Margherita and Jennifer, when they were 12 and 10. I had seen a nice table in Paris and had our carpenter recreate it in plywood.

My granddaughters asked to paint it—we always have paint around the house. Their little brothers were allowed to paint the underside. One day my son Luca came over and goes, "God, this is a work of art!" So he took it away, and had someone put some surface on top of it, and it became the most special object in the house.

Edited Interview by Alexis Swerdloff

Missoni family portrait by Douglas Neill for Purple Magazine.