Ground Cherry

Sow a quarter inch deep in sterile mix and set the flat on a heat mat held at 75 to 85F until seedlings emerge, then grow them on at about 70F soil. Once true leaves appear, thin or prick out so seedlings stand two inches apart, and harden off before they go outside. Ground cherry germinates on warmth, not on calendar date, and a cool flat gives slow, ragged emergence. Counting back from your own last-frost date is what makes this portable from Zone 3 to Zone 9.

Wait until all danger of frost has passed and the soil has genuinely warmed, then plant into rich, light, well-drained ground in full sun at pH 6.0 to 6.5, allowing 18 to 24 inches in every direction. Plants run 1.5 to 3 feet tall and spread laterally, so a cage or short stake helps keep sprawling fruit off wet soil. This crop is a warm-season nightshade that sulks in cold soil, and the extra wait past your last frost costs nothing while a chilled transplant stalls for weeks. The lateral spread is why spacing matters more than the modest height suggests.

Spread two to four inches of straw or other organic mulch around the young plants while you can still reach the soil, keeping it just off the stems. Beyond holding moisture and smothering weeds, mulch is what makes this crop harvestable at all. Ripe ground cherries drop, and they land on straw instead of mud, so you can see them and pick them clean.

Work in a modest general application at planting the way you would for other garden crops, and skip the side-dressings. In decent garden soil ground cherry plants may need no more fertilizer at all. These plants carry strong root systems and pull what they need from ordinary soil. Push nitrogen and you buy lush foliage at the direct expense of fruit, which is the whole point of the crop.

Lay spunbonded row cover or netting over the bed the day you transplant, before three-lined potato beetles find the planting, and site the bed away from where tomatoes, tomatillos, peppers, potatoes or eggplant grew last season. Pull the cover once plants begin flowering so bees can work them. The beetles overwinter in or near last year's nightshade ground and walk to the nearest host in spring, so a cover only works if it goes on before they arrive and the bed is not sitting on their emergence site. Ground cherry is self-pollinating, so an early cover costs you no fruit set.

Keep moisture regular and sufficient once plants are established, and deliver it by drip or soaker rather than overhead sprinkling. The plants will survive drought and heat on their root systems alone, but fruit quality is what suffers first when they are made to tough it out. Wet foliage is how the fungal problems of the nightshade family get started, so keeping leaves dry is free disease control.

Check plants at least weekly, and daily during an outbreak. Look for adults a little larger than a quarter inch with cream to reddish-yellow wing covers bearing three black stripes, then turn leaves over and crush the elongated orange egg clusters on the undersides. Drop adults and the green, shiny-black-headed larvae into a pail of soapy water. UNH Extension reports a second generation appearing in August, though UMN notes it is unclear whether the insect has one or two generations per year, so keep checking after the first wave. This beetle is usually found in low numbers and is not considered a pest except on tomatillo and ground cherry, where it can be abundant and cause significant defoliation. It is the larvae, not the adults, that strip a plant. They cement their own excrement onto their backs as a shield, which is why they get overlooked until the foliage is gone.

The crop tells you when it is ready: the husk goes dry and papery, the berry turns from green to golden, and the fruit falls on its own. Walk the bed every few days and collect the fallen fruit with husks left on. Left in the husk they keep a week or two at room temperature; refrigerate only if you must, as cold storage figures for this crop are not well established. Nothing you pick off the plant by hand is ripe. Ground cherry sheds its fruit at maturity, so the ground under the plant is the harvest, and fruit left lying there rots or reseeds itself into next year's weed problem.