We’ve all been there: you fall in love with your Mexican Creeping Zinnias (also known as Sanvitalia) and wish you could keep those cheerful little yellow blooms going all year long. Whether they’re lighting up your flower beds or spilling over your balcony boxes, it’s tempting to try and bring them inside once the temperature drops. Unfortunately, this little plant has other plans—it’s strictly a “one-season-only” kind of guest.
Mexican Creeping Zinnias are not winter-hardy at all
During the summer, these plants live for the sun. They want to be front and center in a full-sun spot, soaking up every ray. But as soon as autumn rolls around and things get chilly, their time is up. These beauties can’t handle even a light frost; even if the thermometer dips below freezing for just a short burst, it’s usually game over. That’s why, in most climates, they won’t last past the first frost of the season.
Why overwintering isn’t an option
You might be thinking, “What if I wrap the pots in burlap, set them on styrofoam, or move them against a warm wall?” While those are great tricks for many perennials, they won’t save your Sanvitalia. Even if you have plenty of space in a heated greenhouse or a sunny windowsill, bringing them inside isn’t worth the effort. It’s not just about the cold—after a marathon blooming season and producing seeds, the plant has simply spent all its energy. It’s naturally reached the end of its life cycle, so overwintering just isn’t in the cards.
Wait for frost-free days to plant outside
Because they aren’t winter-hardy, we have to treat these as annuals. Their outdoor season typically kicks off in mid-May, once the danger of a late spring frost has passed. They’ll happily stay in their sunny spot as long as the weather stays mild—usually right up until the end of autumn.
How to start fresh every year
Since you can’t keep the old plants, you’ll need to buy new starts every year or, better yet, propagate them yourself! If you let your plants go to seed in the fall, you’ll have plenty of material to work with. You can also find seed packets at any garden center in early spring. To get a head start on those blooms, start your seeds indoors as early as February. They need a bright, warm spot to germinate:
- Sow seeds in pots during early spring.
- Use a high-quality seed-starting mix.
- Barely cover them with soil (they need light to germinate!).
- Prick them out into individual pots once they grow a bit.
- Move them outside only after the last frost.
Quick Tip:
If you live in a particularly mild area, you might be able to get them in the ground by late April. For potted plants, feel free to give them “day trips” out to the balcony on warm afternoons, just be sure to tuck them back inside before the nighttime chill hits!
