Maypop (Hardy Passionflower)

Set out at least two maypops that are not clones of each other - two separate seedlings, or a named plant plus a seedling from another source. Suckers off one plant are the same plant, so a patch that spread from a single crown will not pollinate itself. Give each a trellis, fence, or tree trunk to climb. Passiflora incarnata is self-sterile: its own pollen will not set fruit, so a lone vine flowers all summer and drops every bloom. Fruit only forms when a large bee carries pollen from a genetically distinct vine.

Lay mulch around the base of the vine after the shoots emerge, keeping it off the stems. Mulch cuts weed competition, keeps the roots cool, and holds water - maypop is drought-tolerant but fruits best with steady moisture.

In early spring, cut around a sucker with a shovel, lift it with its roots attached, replant it where you want it, and water it in immediately. Early spring is also the moment for stem cuttings: strip the lower leaves from a 6-8 inch cutting and set it in rooting medium. Maypop spreads by root suckers, so the plant hands you free divisions every year - and lifting them is the same cut that keeps the patch from running, which is the standard way to control its spread.

The top growth dies to the ground each winter - pull and cut away the dead vines in spring, then clip and direct the new shoots onto their support as they appear. Pull suckers coming up outside the bed at the same time. Do not panic if nothing shows early; maypop is a late riser and often waits until the soil is thoroughly warm. The vines are killed to the ground by freezing weather every year while the roots live, so all of next season's growth is new - the old canes are just dead litter, and the plant will run 12 feet or more once it wakes.

While the vine is in flower, check it in the early morning or evening when beetles are cool and sluggish, and knock or hand-pick them into a bucket of soapy water. Leave the caterpillars alone. Skip Japanese beetle traps - they pull in more beetles than they catch and increase the damage nearby. Maypop is the larval host of the gulf fritillary butterfly, so the caterpillars chewing the leaves are the reason to grow it - they slow growth but the vine survives. Japanese beetles feed heavily where they occur, but an established vine tolerates the loss.

Fruit is ready two to three months after the flower it came from. Watch each hen's-egg-sized fruit turn from green to yellowish, then let it wrinkle and soften - that is ripe. Scoop the pulp around the seeds; that arillate pulp is the edible part. Because the vine blooms for months, fruit ripens over a long stretch, so pick repeatedly rather than all at once. Maypop keeps flowering while earlier fruit is still filling, so ripeness tracks each individual flower's date, not the calendar. Green firm fruit is simply unfinished - the sweetness arrives with the color change and the shrivel.

Collect seed in fall after the fruit has begun to shrivel - mature seed is brown with no traces of white. Sow it directly into an outdoor seedbed; that is the best method. If you are holding seed rather than sowing it now, wash the gelatinous covering off first, which is what keeps it in storage. Move seedlings once they have three or four leaves. Seed left in the fruit until it shrivels is fully mature, and an outdoor fall seedbed leaves it in place for spring germination. Sowing several seedlings also gives you the genetically distinct vines that fruit set depends on, since a lone vine is self-sterile.

In the colder end of its range, pile a thick winter mulch over the crown after the tops are frosted down. Make sure the site drains - do not let the crown sit in wet soil over winter. The vine is reliably hardy to about zone 6 and survives further north only where a heavy mulch insulates the roots, which are the part that carries the plant to spring. Root rot is the real winter killer in soils that stay wet.