Nemesia (or “Cape Jewels,” as some call them) are absolute favorites for balcony boxes and hanging baskets. Because overwintering them can be a bit tricky, most gardeners just treat them as annuals. Plus, many modern varieties are actually bred to have a short, one-season lifespan. That said, if you’ve got a green thumb and a “never say die” attitude, you can definitely try to keep them going through the winter!
Nemesia Species vs. Hybrids
In the botanical world, these beauties belong to the genus *Nemesia*. There are about 65 different species out there, but only a handful are used as ornamental plants. On top of the natural species, you’ll find a ton of hybrids. The two most common types you’ll run into are:
- Nemesia strumosa
- Nemesia fructicans
Most of the hybrids you see at the garden center are a cross between these two. Since both the pure species and the hybrids come in a wild array of solid colors and bicolors, it’s almost impossible to tell them apart just by looking at them. However, knowing which is which is key to their lifespan—some are strictly annuals, while others are perennials.
Overwintering Your Nemesia
Since annuals aren’t designed to live past one season, there’s no point in trying to overwinter them. Most of the fancy hybrids fall into this category. The pure *Nemesia* species, on the other hand, are usually perennials.
Most big-box stores only sell the annual varieties. If you’re specifically looking for a Nemesia that you can keep year-round, your best bet is to head to a specialty nursery and ask for perennial varieties.
The Overwintering Process
If you’ve managed to snag a perennial Nemesia, it has to come inside for the winter. You might see some labeled as “semi-hardy,” but don’t let that fool you—they still can’t handle frost. It just means they aren’t quite as dramatic when the temperature dips.
Ideal Conditions
Nemesia and cold weather just don’t mix. They have zero tolerance for frost. In fact, for these plants, 60°F (15°C) feels like a bitter cold snap. If the thermometer hits 55°F (13°C), you’ve reached their absolute limit. Before you move them into their winter home, give your Nemesia a good pruning. After that, they should spend the winter in a spot that is:
- Bright and sunny
- Warm
Keep the temperature at a minimum of 55°F. Watch out for cold drafts, too—opening a window for some fresh air near your plant can be a death sentence in the middle of January.
Now, you might think a cozy, heated living room is the perfect spot, but that’s actually a bit tricky. When it’s warm, the plant wants to grow, which means it needs a lot of light—way more than our short winter days can provide.
Moisture Control
Nemesia like to keep things on the drier side. Even in the summer, they get grumpy if they get rained on too much, which is why good drainage is a must for potted plants. During the winter, they are even more sensitive to moisture. Be extremely careful with the watering can—overwatering by even a little bit can lead to root rot and a dead plant before spring even arrives.
