HEAT? DROUGHT? NO PROBLEM.
Physiological Workaround
Portulaca is a genus that gives us a vegetable, a weed, and a flower. All flourish undaunted by heat or drought, a comforting thought as I drag the hose or lug a watering can around to keep beebalm, an Edelweiss grapevine, and some marigolds and zinnias — all planted within the last couple of weeks — alive.
Portulaca employ a special trick for dealing with hot, dry weather, which presents most plants with a conundrum. On the one hand, should a plant open the pores of its leaves to let water escape to cool the plant, as well as take in carbon dioxide which, along with sunlight, is needed for photosynthesis. On the other hand, the soil might not be sufficiently moist or the pores might end up jettisoning water faster than roots can drink it in, in which case closing the pores would be the ticket.
Portulaca gets around this conundrum by working the night shift, opening its pores only in darkness, when little water is lost, and latching onto carbon dioxide at night by incorporating it into malic acid, which is stored until the next day. Come daylight, the pores close up, conserving water, and malic acid comes apart to release carbon dioxide within the plant. I describe this specialized type of metabolism in my book The Ever Curious Gardener: Using a Little Natural Science for a Much Better Garden.
From the Pampas to my Garden
Let’s start with the flower Portulaca, P. grandiflora, which goes either by a common name that is the same as the generic name, or by the name “moss rose.” In truth, the plant is neither a moss nor a rose. But the tufts of lanceolate leaves do bear some resemblance to moss, a very large moss. And portulaca’s flowers, which are an inch across, with single or double rows of petals in colors from white to yellow to rose, scarlet, and deep red, are definitely rose-like. The plant grows to a half-foot-wide mound, with stems that are just barely able to pull themselves up off the ground under the weight of their fleshy leaves.
Moss rose is native to sunny, dry foothills that rise up along the western boundary of the South American pampas. As might be inferred from its native habitat, this plant not only tolerates, but absolutely requires, full sun and well-drained soil. Such requirements, and low stature, make the plant ideal for dry rock gardens and for edging.
Moss rose is easy to grow from seeds sown at their final home, or started in flats for transplanting. Some gardeners mix the extremely fine seed with dry sand before sowing, to ensure uniform distribution.
Once blossoming begins, it continues nonstop until plants are snuffed out by frost. Moss rose is an annual, but sometimes will seed itself the next season. However, double varieties (plants with double rows of petals) grown this year will self-seed single varieties (plants with a row of petals) “volunteers” next year.
Plant It or Not, It Will Be There
The vegetable and the weedy Portulaca can be dealt with together; they are one and the same plant, P. oleracea. Somewhere in your garden now, you surely have this plant, whose succulent, reddish stems and succulent, spoon-shaped leaves hug the ground and creep outward in an ever-enlarging circle.
The common name is purslane, though it has many aliases, including pussley, Indian cress, and the descriptive Malawi moniker of “the buttocks of the wife of a chief.”
Tenacity to life and fecundity accord purslane weed status. Pull out a plant and toss it on the ground, and it will retain turgidity long enough to re-root. Chop the stems with a hoe, and each piece will take root. Even without roots, the inconspicuous flowers stay alive long enough to make and spread seeds.
My one consolation with having this weed in my garden is that it’s easy to remove, robs little nutrients or water from surrounding plants, and, being low-growing, casts little or no shade. Perhaps it even protects the soil surface from sun beating down on it or pounding raindrops from washing away soil. On the other hand, left unattended, it could take over a garden this time of year.
You Could Eat It
What about purslane, the vegetable? Take a bite. The young stems and leaves are tender and juicy, with a slight, yet refreshing, tartness. Purslane is delicious (to some people, admittedly not to me) raw or cooked, and is much appreciated as a vegetable in many places around the world besides its native India.
I have actually tasted the result of the plant’s specialized metabolism in summer by nibbling a leaf of purslane at night and then another one in the afternoon. Malic acid makes the night-harvested purslane more tart than the one harvested in daylight.
There are cultivated varieties of purslane for planting(!) in the vegetable garden. These varieties have yellowish leaves and a more upright growth habit than the wild forms. Wild or cultivated, the plants can be grown from seed or, of course, by rooting cuttings from established plants.
As far as actually planting purslane in my garden, I agree with the view of another garden writer who said “it is a reckless gardener who would plant purslane.” That does not mean that I do not grow purslane, though, for plenty keeps appearing despite my weeding.
Every once in a while, I again try eating it. I have enjoyed it in salads in restaurants to such accompaniments (or taste and texture disguisers) as feta cheese, olive oil, vinegar, and other strong flavors.
If you do opt to plant purslane, you must replant it yearly. Like the moss rose, purslane is an annual plant. Once established in the spring, both purslane and moss rose need no further care. Now, if only moss rose were a bit more weedy . . .
GROWING FIGS IN COLD CLIMATES video recording now available.
Watch, listen, and learn — on your own time — about GROWING FIGS IN COLD CLIMATES, with a recording of a webinar with Lee Reich. Now available online.
Learn about the nice quirks of figs, subtropical plants native to hot, dry climates, that make it possible to grow and harvest fruit from them even in cold climates. With that covered, I detail some practical applications of this information. Winter care, pruning, varieties, and speeding up ripening will all be covered. If you already grow figs, this webinar will help you grow more or better figs, and be able to manage them more easily. If you haven’t yet experienced the rewards of growing figs, you have a treat in store.
To access this video, go to www.leereich.com/video
TWO DISAPPOINTING FAILURES, TWO DELICIOUS SUCCESSES
Help!!
As flaming red petals drop to the ground beneath my pomegranate bush, I’m not hopeful. Sure, the flowers are beautiful, but the plant is here to give me fruit.
To survive winters here in New York’s mid-Hudson Valley (Zone 5), my plant’s home is in a large flowerpot which I cart into cold storage in late December and back outdoors or into the greenhouse in late winter or early spring. Even my cold-hardy variety, Salatavski, from western Asia, would die to ground level if planted outdoors. The roots would survive that much cold because of moderated below ground temperatures, but new stems that would rise from ground level would need to be more than a year old before flowering.
Potted pomegranate, but NOT mine
Growing in a pot, my pomegranate (and other potted fruit plants) need regular pruning and repotting. To prune the pomegranate, I snip off young suckers growing from ground level, shorten lanky stems, and thin out stems where congested. I repot the plant every 2 or 3 years, cutting off roots and potting soil from around the root ball to make room for new potting soil.
When flowers do appear, which they do over the course of a few weeks, I dab their faces with an artists’ brush. Going from flower to flower spreads the pollen from male flowers to the female parts (stigmas) of the hermaphroditic flowers.
Male pomegranate flowers
Hermaphroditic pomegranate flower
Then I wait, my eyes concentrating on each flower and hoping to see the base swelling. Problem is most, some year all, the flowers open and then drop. Occasionally, in past years, a flower or two has swelled into a mini-pomegranate. Then also dropped.
Swelling pomegranate fruitlet
I’ve ministered to this plant for years and it has never rewarded me with a single fruit. Help! Any suggestions?
Not So Idle Threats
Every summer, as my pomegranate drops its last flowers, I’ve threatened it with the same fate I wrought upon another of my subtropical fruit plants, pineapple guava. Beneath the thin, green skin of this torpedo-shaped fruit lies a gelatinous center with a minty pineapple flavor.
Pollinating pineapple guava
Over the course of growing this fruit for many years, I did harvest a few, small fruits from this plant, but not enough to keep me from reincarnating it as compost. (The flowers, however, reliably produced, sport the most delicious, fleshy petals of any that I’ve taste, with a strong, sweet minty flavor.)
A Most Delicious Fruit
Not all has been failure with my growing subtropical fruits.
My most recent success has been with Pakistani mulberry, Morus macroura, native to Tibet, the Himalayas, and mountainous regions of Indochina. I first tasted this fruit a few years ago at a nursery in Washington State and was swept away by the delicious flavor, sweet with enough tartness to make it interesting, and a strong berry undertone. (Yes, mulberry does have “berry” in its name, but botanically, it’s not a berry; it’s a “multiple fruit.”)
Besides having great flavor, Pakistani fruit is also notable for its enormous size, each one elongating, when ripe, to between three and five inches!
Pakistani mulberry is easy to grow and needs no particular coaxing to bear plenty of fruit, which it does over the course of a few weeks. Mine grows in a pot measuring a little over a foot wide, with the tree rising about four feet high. Fruits are borne on new shoots that grow off older stems, which keeps the tree very manageable. Shortening those older stems each year makes it easier to muscle the plant through doorways to move it indoors for winter and then back outdoors when weather warms a little.
Very Easy, Very Successful, Very Delicious
My longest term and greatest success with subtropical plants has been, of course, with figs. (I write “of course” because I’ve written a whole book whose content is described by its title, Growing Figs in Cold Climates, and now is available as a video of a webinar I have presented on that topic.)
Like mulberries, to which they are related, figs — most varieties — can bear fruit on new shoots that grow off older branches. 
So, like mulberry, the plants can be pruned back some so they’re more manageable to be protected from bitter winter cold. An in-ground plant, then, could be protected from bitter winter cold by being swaddled upright or lowered to the ground, even trained to grow along the ground; a potted plant is more easily maneuvered into a garage, unheated basement, or other cool location for its winter rest.
Right now, there’s nothing for me to do with my figs except watch them grow. Small figlets now sit in the plants’ leaf nodes. They’ll just sit there, doing nothing, for a seemingly long time. Once ripening time draws near, the figs suddenly puff up, becoming soft and juicy and developing a honey sweet, rich flavor.
