HOUSEPLANTS THRIVE DURING MY CUBAN GETAWAY
Water In Air, In Soil, In Reserve
My houseplants enjoyed my absence more that I expected. I thought it might be harder on them. After all, with spring in the air (indoors) for a few weeks now, they were all pushing out new shoots from the ends and along stems that had lain dormant all winter. Citrus, avocado, and amaryllis were even flowering, and rosemary was getting ready to flower.
Lack of water was going to be the threat, 5 days of it, while I was far away wandering up and down streets and in and out of alleys of Havana, Cuba.
Through winter, I had eased my houseplant watering chores by using “water siphons” (aka “hydrospikes” or “self-watering probes”). These porous ceramic probes, filled with water and pushed into the potting soil, have the thin, flexible tubes coming out of their caps plunked into mason jars filled with water. I knew well just how thirsty the plants were, watching the water in the reservoirs into which the tubes that connect to the ceramic cones drop daily, in some cases a cup or more per day.
Plants cool off by letting water evaporate through little holes in their leaves, called stomates. So leaving the house thermostat set to cooler temperature was going to help slow water loss.
Evaporation is faster, whether through stomates or from the potting soil, the drier the air. Heat from radiators is less drying than that from the wood stove, our usual source of heat — also helping plants that might be pining away in my absence.
I poured water into the saucers in which each pot sits. As this water evaporates it creates a microclimate around nearby plants, a microclimate slightly more humid than that of the rest of the house, cutting down water loss from the potting soil and through the leaves. The humid microclimate was made more so by cozying plants in a cluster right up next to each other. Pebbles in the saucers bumped up this benefit by increasing the evaporative surface area.
To further help plants through their period of neglect, I filled the saucers with more water than usual, with the water level a smidgen above the bottom of the pots. As the potting mix dried, it could suck this water into the pot by capillary action. I don’t usually let water sit in the saucers above the level of the bottom of any resident pot because then the bottom of the pot becomes waterlogged, eventually leading to dead roots. I figured a few days would do no harm, and surely less harm than would drying out of the whole plant.
My final ministration was to cut open a clear dry cleaner bag and drape it loosely over the clusters of plants to maintain even higher humidity.
The upshot: The plants did not miss me even a little. They looked healthy and happy upon my return, perhaps even more so than with five days of constant attention!
Visitando El Jardín Botánico Nacional
One day in Cuba I ventured beyond Havana for a tour of the Jardín Botánico Nacional, or National Botanical Garden, which is adjacent to Parque Lenin (Vladimir, not John) Park. We bounced along on a tractor-pulled wagon through a landscape devoted to plants native to Cuba, then on into a savannah of plants of African origin, to groupings of plants indigenous to Latin America, and on through other tropical climates and ecosystems.
A few greenhouses there create special environments. One was a tropical rainforest greenhouse, with humidity kept high with frequent, automatic watering. A houseplant such as maranta formed an expansive groundcover there, and other familiar houseplants, such as peperomia, philodendron, begonia,, and spathiphyllum, either spread all over the ground or reached heights you would never see in a house.
A dry greenhouse, the covering, this time, to shed rainfall, was home to succulents and cactii. One cactus that caught my attention, especially so with Cuba’s connection to the Soviet Union, was the “Russian soldier cactus.” The upper portion of this upright cactus was furry and brown, just like a Russian soldier’s hat. (As far as cool, common names the Cubans have for plants, another one was “tourist tree,” so-named for its red, peeling bark, just like the skin of pale tourists that get too much tropical sun.)
Another Orchid!?
I’m very happy with my two orchid plants — Dendrobium kingianum, the pink rock orchid, and Odontoglossum pulchellum, lily-of-the-valley orchid. Both bloom reliably once a year, in winter, for over a month.
But one of the orchids at the Jardín Botánico Nacional caught my attention for more than its beauty. Spathoglotis plicata, sometimes called Phillipine ground orchid, blossoms all year ‘round. It’s a terrestrial orchid that’s also easy to grow, not needing an excess of light. I’m going to get one to add to my collection.
Orchids can become an obsession; I hope I’m not about to fall down a rabbit hole.
BLEEDING PLANTS, WHAT ABOUT RABBITS?
Bleeding Is Okay
Everyone wants to prune this time of year. And rightly so. It’s a good time to prune most trees, shrubs, and vines, as it was a couple of months ago and, looking forward, will be until about when these plants come into bloom. Or, finished blooming, in the case of those plants whose pruning gets delayed until after we all get to enjoy their early blossoms.
A reader wrote me about her Japanese maple, which needed to have one of its multi-trunks cut off. Should she do it now or in autumn? If lopped back now, would the tree bleed to death? Would the gaping wound get infected, possibly leading to the demise of the whole tree?
Japanese maple in fall
Bleeding sap generally does more harm to gardeners’ psyches than to plants’ physiologies. My grape and hardy kiwi vines bleed when I prune them this time of year, with no harm done. So why worry about harm to a maple?
(The bleeding of grapevines that climb the arbor over my patio does have one downside. It’s very pleasant to sit outdoors on that patio on warm, spring days; it’s very unpleasant to sit where sap drips on my head.)
Root pressure of water being forced up the vines is what makes grape and kiwi vines bleed. Once leaves unfold, they take up that pressure and bleeding ceases.
Root pressure is not what forces sap (which sounds more benign than “bleeding”) out of wounds of maple trees. With maples, cooling temperatures cause gas bubbles in xylem cells (the inner ring of trees’ cells in which liquid is conducted upwards from the roots) to shrink and to dissolve. Something’s got to fill that newfound space, so more liquid is sucked up from the roots and into the cells. As temperatures drop further, ice forms and gases are locked within the developing ice. Come morning, pressure builds in the cells as rising temperatures melt the ice and release the gases. The expanding liquid is forced out any holes in the bark, whether from a maple sap spile or from a pruning wound.
Although maples bleed for a different reason than do most other plants, the bleeding itself causes no harm to the plants. The reason small maple trees, with trunks narrower than 6 inches in diameter, should not be tapped is because the wound left by the tap hole extends within the trunk beyond the hole; sap will never again travel past the wounded area. A tap hole is large in relation to the size of a small tree’s trunk, so significantly restricts liquid flow.
Of course, there’s no need to conduct sap up a trunk that’s been lopped off. So, Barbara, go ahead and prune, now, when the gaping wound can soon begin to heal. Autumn, which leaves a gaping wound exposed to the elements and pests until spring, would be a very bad time to prune.
A Wabbit!!!!
I looked out the window awhile ago to see a rabbit crouched against a backdrop of pure, white snow. How cute. NOT! It’s the same old story. Farmer McGregor and Peter Rabbit, and now farmdener me and some other rabbit.
A few days previously I had noticed that some bark had been nibbled off the pencil-thick “trunks” of some young, grafted trees — the handiwork of those awful furballs. That nibbling probably won’t kill the small plants but will set them back a year, or more, if the nibbling kills the scion down to the graft.
As for the rabbit and its probable kin, I’m setting traps. Unfortunately, my Peter Rabbit seems to enjoy my plants more than anything I put in the trap.
Rabbit, At Bay
I’ve kept my Peter Rabbit at bay from all my older trees this winter with diligence and hardware cloth and or commercially available plastic spiral tree guards. The protection goes 2 feet above ground, or higher, not that a rabbit could reach that high — except when there’s snow to give it “a leg up.” The light-colored spirals also protect the thin barks of young trees from sunscald, which results when sunny, cold winter days warm the bark, whose temperature then plummets as the sun drops below the western horizon.
I remove all the spirals in spring so insects can’t find shelter from birds beneath the spirals.
Monthly, throughout winter and into early spring, I also sprayed plants with Bobbex, a mix of “putrescent whole egg solids,” garlic, and cloves that is repellant to rabbits, as well as deer (and me).
And finally, there’s Sammy, my trusty dog who would chase away any rabbits if he happened to be awake, happened to be on the right side of the house, and happened to see them.
MOVING ALONG, INSIDE AND OUT
Figs Awakening
Even in the cool temperature (45 degrees Fahrenheit) and darkness of my basement, the potted figs can feel spring inching onward. Buds at the tips of their stems have turned green and are just waiting for some warmth to burst open. Or, if the plants just sit where they are long enough, the buds will unfurl into leaves and shoots. Which would not be a good thing.
My goal is to keep the plants asleep long enough so that they can be moved outside when they will no longer be threatened by cold temperatures. How much of a threat temperatures pose depends on how much asleep the plants are. Fully dormant, a fig tree tolerates temperatures down into the low 20’s. Even now, as they are just barely awakening, they can probably laugh off temperatures into the mid-20s.
If the buds expand into shoots and leaves, they’ll be burned by any temperature below freezing. And especially so if those new shoots and leaves get started indoors, where warm temperatures and relatively low light makes for overly succulent growth. Bright sunlight, even without freezing temperatures, can then cause damage.
Fig plants that start growing in earnest indoors get presented with two options. The first is to get them to the sunniest window in the coolest room so that growth is more robust, then move them outdoors after any threat of frost has passed — about the same time as tomato transplants get planted out. (Around here, that’s about the third week in May.)
The second option is to move them outdoors as soon as temperatures won’t again fall below the mid-20s. Temperatures below 32 will burn the succulent, new shoots and leaves, but plants will push forth new growth well-adapted to the great outdoors. If an Arctic blast is predicted, with lower that usual temperatures — that is, below about 25 degrees Fahrenheit — the plants need to be moved temporarily to the garage, mudroom, or other convenient shelter.
Different Strokes For Different . . . Figs
A fig’s treatment depends on the variety. Genoa, Excel, and Ronde de Bordeaux are three new varieties that I hope to taste this summer. They’ll get first-class coddling: Moved outside soon, then put into temporary shelter at the slightest hint that damaging temperatures could arrive. I might just put the others outside, and leave them there.
The Kadota fig gets planted, in its pot, right in the ground. Its roots will grow out through all the holes I drilled in the side and bottom of the pot so the plant becomes self-supporting, waterwise, until fall. I’ll plant it out soon, even though once it’s planted, it’s staying put all season long. (I have a backup plant.)
Too Weird To Eat
Moving forward into spring — on into late spring — brings dogwoods into bloom. Blossoms of our native flowering dogwood (Cornus florida) will soon be followed by those of kousa dogwood (C. kousa), and also called Japanese or Korean dogwood), native to east Asia.
The flowers of both species are very small and pretty much green. “Not so!,” you say, thinking back to last spring’s show of large white or pink petals. Those large white or pink things are, in fact, not petals, but bracts, which are modified leaves that, admittedly, serve pretty much the same function as petals, that is, to look pretty, attract pollinators, etc.
Over the years, the spring show from flowering dogwoods has become sparse because of powdery mildew and other diseases. Which is why kousa dogwood, which is disease resistant, has been increasingly planted.
Flowering dogwood can have either pink or white flowers — whoops, I mean bracts. Until recently, kousa dogwood came only in white. But now, breeders at Rutgers University, after decades of work, have introduced Scarlet Fire kousa dogwood, a cold hardy (Zone 5 to 8), disease resistant variety bearing pink bracts.
The flowers of kousa dogwood, whether pink or white bracted, are followed by edible fruits. The round fruits are the size of a quarter, dark pink, and very weird-looking. To me, they look like water (naval) mines, not a very friendly association for a fruit. Their appearance has also been described as that of a sea urchin shell, also not very gustatory. Inside, the flesh is sweetish and mealy, something like a cross between mango and pumpkin — not my two favorite flavors, but even if they were, those dark pink water mines are too off-putting in appearance for me to more than sample them (just so I could report on their flavor).
Still, kousa fruits add to the show from the flowering bracts and the healthy foliage.
