This one won’t require space on your windowsill.
Most of us think of begonias as either annuals or houseplants, but one variety is garden hardy from zones 6 through 9. Begonia grandis subsp. evansiana can reach 2 feet or more in height with pink or white blooms which appear from mid-summer through mid-autumn.
This plant prefers a position in partial sun to full shade and rich, moist but well-drained soil. Its foliage—green with red undersides and flower stems—turns orange and dies back to its tubers in the fall to reemerge green again in spring or early summer. The culture is very similar to what hostas prefer.
In the coldest parts of hardy begonia’s range, it may not appear until June. Therefore, you can place it near spring-flowering bulbs if you want. It won’t overshadow their blooming, but can help cover up their yellowing foliage. Small bulbils often drop from the begonia’s leaf axils in autumn, so you may have more plants than you expected the following year.
Since I live in Zone 5, I’ve always wanted to try hardy begonia here, but hadn’t had much luck with a previous effort to start it from seed. So, when I saw both seeds and bulbils listed in a November seed swap, I grabbed both to hedge my bets.
The trader who was offering them suggested sowing the bulbils on the surface of soil and placing them in the refrigerator for one to two months. Since our refrigerator always is overcrowded with other things, I set my bulbils—with their container encased inside a plastic bag—under plant lights in our chilly back room instead. Placed there in December, they began sprouting in February.
If I recall correctly, the seedlings—er, bulblings—that were supposed to be white-flowered also had white flecks on their leaves, which the pink-flowered ones did not. The flecks faded after I moved the plants outdoors in spring.
I sowed the seeds in February by pressing them into the surface of seed-sowing mix and placing their container under grow-lights in our cool basement where the temperature stays in the 60s or below. The seeds took eleven days to germinate.
I definitely would recommend the bulbils, if you can get them, since the tallest of the plants grown from them stands at about 10 inches at the moment, while the tallest of the seedlings is just a little above 2 inches. Though, granted, that could be because I haven’t gotten around to transplanting the latter! Hardy begonia reportedly roots easily from cuttings too.
And, yes, you can keep it in a pot if you like. The fact that it will grow in the ground doesn’t mean that you have to grow it there. The huge specimen pictured above reportedly is occupying a very large container.
I’ll probably have to mulch my tubers well if I want them to survive here in zone 5. Those of you in warmer zones may find all that seed and bulbils dropping makes this begonia a bit invasive. But plants that bloom well in the shade are not common enough for us to spurn this one for its profligacy!
Photos: The banner photo is by Gabrielle, the second photo by htop, and the third photo by Beverlyhy, all from the Dave's Garden Plant Files.