The Ground Cherry is a species of Physalis plant. These are not cherries. Ground cherry plants are related to the tomatilo. They are a nightshade, like a tomato, and originate from Central and South American. A common variety you might come across is Aunt Molly's which is what I've grown. The Ground Cherry is not the same as the Cape Gooseberry but closely related with similar taste and growing habits.
I have never seen them offered for sale as transplants but you should be able to find seeds for sale from a few of the larger mail order seed companies. Basically, if you grow them like tomatoes, they'll turn out fine. The seeds are very small and can be hard to get started. Start them indoors around the same time you would normally start tomatoes. Don't cover the seed with too much potting soil. I always over-plant Ground Cherry plants when I start them because I don't have much luck getting them started. But once they pop up I find they do ok. Plant them out a couple of weeks after last frost, just like tomatoes.
Container grown ground cherry plant.
Flowers form everywhere the vines fork.
They grow into short, wide bushy plants. I've heard that in some places they grow along the sides of highways and roads like weeds. Because they produce so much fruit with so many seeds, once established they continuously re-seed their growing area and continue to thrive year after year. My plants will spread out to over a 1m in width but never grow much more a 1/2 meter in height. The fruit form inside a loose papery husk from small flowers that appear on the plant anywhere the branches fork. The plant likes to sprawl which means lots of branching and that means lots of fruit. I would say up to 100 per plant.
Being on a balcony, naturally I grow my Ground Cherry plants in containers and I haven't had any problems. They seem to do ok even without full sunlight and are not very demanding of anything really. They are rather resilient considering how beaten up the plants on my balcony get from the wind. I had a Ground Cherry plant fall over once and partially uproot itself. I propped it back up with a stick for support and it did just fine. I've had branches bend and drop but never break clean off, unlike some Cape Gooseberry plants I've grown. The branches grow rather woody and can bend easily.
A Ground Cherry plant will typically provide ripe fruit in 70 days. That's about how long the Aunt Molly's plants I grow take to mature. When ripe, the fruit will just fall off the plant. Sometimes I give my plants a little shake to see what falls off. As the fruit ripens, the husk will turn from green to light brown and the berry inside will turn from green to golden yellow. I find that they aren't quite ripe enough just after falling from the plant with lots of green remaining in the husk. I keep them inside in a bowl and within a week the husk is dry. Some of the berries retain a green tint or veining but they seem ok. Don't eat the husk. And don't eat the unripened fruit - they don't taste all that great. Apparently ripe Ground Cherries in their husks can keep for up to a month.
Some gound cherries I collected. Some are ripe and others need a bit more time.
Inside a Ground Cherry. Meaty. Lots of seeds.
Ground Cherry fruit has a taste that is a little tart, somewhere between citris and pineapple, with a bit of acidity. The actual taste will depend on the variety grown and the growing conditions. The ones I have sitting in a bowl by my computer right now taste kind of like cherry tomatoes. The ground cherries I grow are rarely very sweet and I think my cape gooseberries usually turn out sweeter. Once you get them started, they take off and don't seemed bothered by too much neglect or abuse. But they do take up a lot of real-estate on the balcony, being a low lying spreader. I prefer Cape Gooseberries though. You get lower yields and bigger plants but unlike the Ground Cherry, they grow vertically which makes them more manageable on the balcony.