MIX POTTING MIX
Coconutty Coir
For a couple of years, a block of coir has sat atop my bale of peat moss.
Peat moss, the product of slow, anaerobic decomposition of organic materials, accumulates, at a snail’s pace, in bogs: an inch or so depth per thousand years. To mine peat, the bog must be first drained. Besides upsetting bogs’ unique ecological habitats, draining the bogs aerates them, sending some of the carbon wafting into the air.
But peat is good stuff for potting mixes. My mixes are made up of equal parts peat moss, soil, compost, and perlite, along with sprinklings of soybean meal (for nitrogen) and kelp (for insurance against lack of any trace elements). Peat’s contribution to the mix is a long-lasting source of organic matter that helps cling to moisture and to nutrients, important in the relative confines of a flower pot.
Coir is marketed as a substitute for peat in potting mixes. A sustainable substitute, made from the fibre left around coconut husks after they’ve been cracked open to remove their meat.
This spring it was time to put that block of coir to the test, with a head to head comparison to peat. (I’ve tried this comparison before, but more casually.) The block, after slurping up a large volume of warm water, was ready to mix with the same ingredients as I mixed with the peat moss.
Some potting soil components
Both mixes went into their separately labelled , 5 gallon buckets. Each mix then was used to fill one-half of a few GrowEase Seed Starter Kits. Into one of the kits went lettuce seedlings, another got tomato seedlings, and a third got pepper seedlings. The 24 cells of each kit are automatically watered via a capillary mat that sits atop a water reservoir, providing very uniform moisture to all cells within a kit and from one kit to the next.
Peat, Coir Standoff
Drum roll . . . and the winner is . . . well, as I recently wrote, some of this year’s seedlings grew very poorly, perhaps, I’ve hypothesized, due to the soil I used, or the compost, both of which vary some from batch to batch. The overcast, cool conditions in the greenhouse during critical growth periods also could be to blame.
Differences in growth between coir and peat based mixes were not great, but tipped slightly in favor of the peat based mix. This, incidentally, jives with my previous, more casual observations. It also jives with more rigorously planned and executed, published research.
Coir Still in the Ring
The results of all this testing don’t spell continued destruction of peat bogs. Coir might still be a viable alternative.
Peat and coir are not the same material. I perhaps should not have used the same ratio for coir as I’ve long used for peat in my mix. There’s some evidence that coir, as it slowly decomposes in a potting mix, can suck up nitrogen at the expense of plants. If so, more soybean meal in my mix could solve that problem. Other nutrients, or lack thereof, could also come into play, as could anti-growth factors, such as phenolics, known to be present in coir.
More playing around is needed with coir.
Peat and Coir Substitutes
No need to put all our eggs in one coir basket. Other organic materials can and have fulfilled the niche of peat (and coir). And our culture has no lack of organic “waste” products. Composted bark has been used in commercial mixes for many years, as has sawdust. More exotic, around here, at least, would be rice hulls.
Home-grown and readily available “organics” for a potting mixes would be compost and leaf mold, both of which I’ve used in rougher mixes, such as for temporarily repotting small trees.
The point is that any of these organic materials, including coir, could make a good potting mix if ratios and amounts of other materials are adjusted accordingly.
Gardening (and farming) should be, and could be, sustainable; even the potting mixes used to raise seedling or grow potted plants.
Now Perlite, Hmmmm
The other major component of any potting mix is some aggregate, for providing good drainage. My mixes use perlite. Not sustainable. More on that another time.
SUMMER WEATHER, PLANT THE GREENHOUSE
Ginger on the Way
Now that summer-y weather has blown in and is here to stay, it’s time to plant the greenhouse. Plant the greenhouse?! This time of year? Yes. No reason to let all that real estate go to waste through summer.
Ginger plants that I started from supermarket tubers a couple of months ago were crying out to be released from the confines of their 4-inch pots. Warming their bottoms on the seed-starting heating mat pushed them along even when early spring skies were overcast and the greenhouse relatively cool. Ginger is a tropical plant that shivers even when temperatures drop below 55°F.
I never could see the rationale for the current interest in growing ginger in northern regions. That is, until I tasted freshly harvested, baby ginger. This far north, ginger rarely has time to develop the mature, tan-skinned roots you see in supermarkets. No matter, because immature, or “baby,” ginger, which is ginger harvested before it matures, is better — a white, tender, tasty tuber. It doesn’t keep or ship as well as mature ginger, which is no problem for backyard growing or local sales.
So 4 ginger plants went into two greenhouse beds. I’ll dig up the ginger in September, freeing up space for lettuce, celery, kale, and other cool weather salad makings that will inhabit the winter greenhouse.
Early Curcurbits
One can eat only just so much ginger. (We’re still using last year’s harvest which, for long term storage, was sliced thin and put into jars with vinegar.) What about other greenhouse beds that are being vacated as the last of winter’s lettuce, celery, kale, and chard get harvested and cleared away?
Cucumbers and melons love heat, so a few extra plants that I started back in early May went into beds.
The permanent fixtures in the greenhouse, the plants that really help the greenhouse earn its keep, are the four fig trees — Bethlehem Black, San Piero, Brown Turkey, and Rabbi Samuel — planted right in the ground. The largest of these has a trunk 7 inches in diameter. All yield bountiful crops daily in August and September, and less bountiful ones going into October.
Tropicals and Subtropicals Summer Vacation
In a reversal of fall, tropical and subtropical plants that had been moved into the greenhouse and house are now lined up outdoors, ready to offer fresh black mulberries, Pakistan mulberries, pineapple guavas, pomegranates, Golden Nugget mandarins, olives, dwarf Cavendish bananas (probably no fruit from this one, just a very tropical look), and a few other varieties of figs, in pots.
(My black mulberry is the species Morus nigra, one of the best-tasting of all fruits, but is not cold hardy here. Black-colored mulberries that grow all over the place outdoors here are, despite black fruits, species of red or white mulberries, or their hybrids.)
Any of my tropical and subtropical plants, given their druthers, would reach 8 feet, 10 feet, or even more feet skyward, and spread their roots many feet in all directions. Here, they can’t do that or they would be too big to move or to house in winter.
So I mixed up a batch of potting soil, and started root pruning. It sounds brutal, and it is, but plants recover nicely and then happily have new soil to explore. Basically, I slide a plant out of its pot, stand it upright, and then start slicing off the outer edges of the root ball. Pruning shears take care of any roots too large to slice with a knife.
The finished root ball is an inch or two smaller in diameter than it started out. How much to remove depends on the initial size of the root ball — larger plants get more removed — and, to a lesser degree, the kind of plant. Figs, for instance, tolerate especially brutal treatment.
So much for the roots. To keep it manageable, the plant also needs stem reduction. Some stems get shortened, some are removed in toto, and some are left untouched. Who gets what treatment depends, for fruiting plants, on their fruiting habit — just where and how they bear fruit. Figs that bear on new shoots can be pruned rather severely; pineapple guavas bear on new shoots growing off older stems, so only moderate pruning is tolerated so that some older stems are preserved, etc.
After root and shoot pruning a thorough watering, plants are ready for a year or two of good growth before they will again feel constrained.
WINTER’S LEGACY, STILL
Half a Pear, Tree
Perhaps last winter’s weather — extended cold, but not frigid temperatures, and hardly any snow — is still playing games with us. Perhaps it is mischief from the early, extended, very warm weather in early spring that was followed by plummeting temperatures and our biggest snowfall (4 inches) of the year. Whatever the reason, some weird things are going on this growing season.
Look at one of my old pear trees, for instance. This tree might be called my “sample” or my “first cut” pear tree. When I hear tell of a pear variety that might be worth growing, I get a scion and graft it onto this tree. The scion bears quickly, in theory, at least, and, if it passes the “first cut,” perhaps it will warrant its own tree. There’s not enough time or space to put every Tom, Dick, and Harry of a pear variety on its own tree.
The tree now has about a dozen varieties of pear growing off various branches. That’s not weird, though. What is weird is that, right now, the top half of the tree is fully leafed out while limbs on the bottom half of the tree are leafless.
A disease? Doubtful. A disease killing that much of a tree at once would probably originate in the trunk or roots, in which case the whole tree or only the upper portion would be leafless. And anyway, those leafless limbs are not dead. Cutting beneath the bark reveals living, green tissue.
My hypothesis — a weak one — is that the cold snap in spring, where temperatures in the ‘teens followed a spate of temperatures in the 70’s, is the culprit. Warm temperatures in late winter and spring cause plants to rapidly awaken and lose the cold-hardiness they maintained through the coldest parts of winter. The pears seemed quite awake when that cold spell struck.
But why was only the bottom portion of the tree affected? (Here’s the weakness in my hypothesis.) Windless, clear nights, such as during spring’s cold snap, bring a temperature inversion. Under such conditions, denser cold air can settle down near ground level. Even a few feet of elevation can make a difference, one that’s evident when riding a bicycle or motorcycle on a clear summer night on rolling terrain.
So maybe the bottom half of the pear tree experienced temperatures just below the tipping point where enough damage occurred to delay leafing out.
Other Pear Trees, Still Whole
No other plants, including other pear trees, experienced this bifurcation. Then again, the “sample” pear is all by itself where the microclimate might be slightly different.
During that cold snap, the other pears were quite awake, seemingly just about ready to spread their blossoms. I was braced for a total crop loss. Weirdly, the trees went on to blossom just fine and now have what’s shaping up to be a decent load of fruit on them.
Seedling Troubles
More weirdness: Every season I sow vegetable seeds according to a schedule I’ve developed over the years. I sow the seeds in mini-furrows in flats of potting soil or potting soil topped with a mix of peat moss and perlite. Every season I make my own potting soil from a mix of equal parts peat moss, perlite, compost, and garden soil, with everything sifted together through half-inch mesh hardware cloth.
And every season I’ve had sturdy, lush green transplants to set out over the past few weeks. Not this season. Too many of the transplants are stunted, with flaccid leaves that are not uniformly lush green. Some have slight, interveinal yellowing of oldest leaves, some have slight reddening of veins, hinting, respectively, at insufficient nitrogen and phosphorus uptake .
As usual, the weather could be blamed. Those auspicious, sunny days of late winter gave way to a long period of overcast days. Rain or not is not the issue because seedlings were in the greenhouse, watered as needed. Overwatered? Underwatered? Cool greenhouse temperatures could limit root growth, in turn limiting uptake of nutrients even if they are in the soil.
The potting soil could be the culprit. Although ingredients of my mix are always proportionately the same, the compost isn’t exactly the same from year to year. Same goes for the “garden soil” that goes into the mix. I scrape it up from various places around the yard: the bottom of a finished compost bin, from my catch-all extra soil bin, from top layers of a pond I’m occasionally hand-digging.
A couple of other gardeners and farmers have concurred with their seedlings’ poor growth this year. Perhaps it was the weather? Do you want to weigh in?
And the Winner Is . . .
Very few people offered hypotheses on why only one limb of my plum tree was in bloom. Neither the weather nor any other environmental condition was to blame. In fact, I had grafted the tree a few years ago to four different varieties in order to spread out the harvest date and offer a greater variety of plum flavors.
The bulk of the tree had already flowered.The one blooming branch was that of beach plum, the least reliable, smallest, and, to my taste, least flavorful of the lot. Perhaps I’ll graft that limb over to yet another variety.
Congratulations to Tom, tkjazzer@gmail.com, on winning a copy of my book Grow Fruit Naturally.
