Grow Your Own: Ground Cherries
Ground cherries are a fun and unique fruit to grow that are as delicious as they are rare in this era.
You won’t find this cousin of the tomato at the grocery store, and I’ve never spotted them at my local farmer’s markets. Luckily they’re easy to grow, they take up little space in the garden, and they’re very prolific.
The name “ground cherry” actually refers to many species within the genus Physalis, in which the tomatillo is also found. The Physalis genus is a member of the Solanaceae (Nightshade) family along with tomatoes and potatoes.
The most common cultivated ground cherry species found today is P. pruinosa, also known as the strawberry ground cherry. Other common names include husk cherry and husk tomato.
The majority of the 80 or so species in this genus are native to North, Central, and South America, with nearly half originating in Mexico. They prefer warmer climates, and will generally do well under the same conditions in which tomatoes, peppers, eggplants, and similar crops thrive.
Ground cherry plants are small shrubs with leaves that somewhat resemble a potato plant, often with a purplish tint to the stems. They generally won't get more than two or three feet tall, but they can spread out a couple feet in all directions. In my experience, two plants can fit comfortably next to each other in a four-foot-wide raised bed.
The ripe fruit is golden yellow to light orange in color, about the size of a blueberry, and encased within a papery husk like a tomatillo. The texture is much like a cherry tomato, and the taste is reminiscent of strawberry and pineapple. I'm told they're great in jams, pies, preserves, and salads, but every ground cherry I've ever grown has gone straight from husk to mouth!
Where to find ground cherry seeds:
Ground cherry seeds can be found from many of the more popular organic and heirloom seed purveyors. My seeds came from Baker Creek; other varieties are available from High Mowing and Seed Savers Exchange.
How to grow ground cherries:
1. Start seeds indoors in late winter/early spring.
Much like tomatoes and peppers, ground cherries need to be started indoors early in the season, then transplanted out in the garden when it’s sufficiently warm. Grow lights are your best option, but an especially sunny window (minimum 4 hours daily) will work if you don’t have anything else. Start your ground cherry seeds about 6 to 8 weeks before your last frost date – here in Kentucky (Zone 6), this is generally in March.
A note on germination: I’ve had low success rates with germination in the past, and I’ve heard similar reports from others. I’m pretty sure I’ve discovered the problem, at least for me, and it doesn’t have anything to do with the viability of the seeds. The problem lies in the fact that ground cherry seeds are so very tiny.
It’s crucial (as I’ve learned the hard way) to sow your seeds in potting soil that has been thoroughly saturated beforehand. There are many good reasons for this, but in the case of ground cherries, you need the “stickiness” of the wet potting soil to hold the seeds up at surface level. If you add the seeds to dry soil, they can easily slip through to the bottom of your flats, and you won’t see them popping up anytime soon.
It’s also worth noting that ground cherries take quite a bit longer to germinate than many other seeds. Expect 12-16 days minimum, but I’ve seen it take more than 20. Be sure to keep your flats evenly moist for the duration.
2. Transplant outdoors well after last risk of frost.
Ground cherries need warm soil temperatures, like peppers or eggplants. Wait until at least 2 to 4 weeks after the threat of frost is gone, when temperatures outdoors are consistently in the mid-60s F at night. This translates to mid/late May here in Zone 6.
It’s a good idea to harden off your seedlings for at least a week or so before transplanting by taking them outside during the day and bringing them back in at night. Much like tomatoes, ground cherries appreciate good drainage, so raised beds are ideal. And as with their Nightshade relatives, they prefer not to get their foliage wet when watering.
Be sure to add a good handful or two of compost to the hole you plant into. Ground cherries will sprout new roots along the stem if given the opportunity, so transplant them as deep as you can, like you would with tomatoes, to encourage a strong, sturdy stem.
3. Wait for the husk cherries to fall to the ground.
Common varieties of ground cherries take about 70-75 days from transplanting to reach maturity and yield fruit. Here in Kentucky, this tends to happen in mid to late July. They're extraordinarily easy to harvest – just wait until the fruits fall to the ground (hence, ground cherry) after the husk has dried out and turned from green to pale brown.
The berries may be a little on the green side when they fall. In that case, let them sit for a few days, until they turn to a pale, creamy yellow-orange all the way through.
Be mindful to pick up every fruit that falls – ground cherries can be very weedy volunteers in following seasons. As with other Nightshades, their production will come to a halt around the time of your first frost in the fall.