Thursday, February 28, 2013

Excitement in some Seeds

There's still some space left in the March 10th lecture/workshop in Philadelphia. In the morning, I'll do a photo presentation about pruning fruit trees, shrubs, and vines and then, after lunch, we'll go out into the real world, at the Awbury Arboretum's Agricultural Village. For more information and for registration for FRUIT PRUNING SIMPLIFIED, please visit:

And now, on to what's happening up here on my farmden in New York's Hudson Valley . . .

Some inch-long, tapering white sprouts -- roots -- caused quite a stir today. For me, at least. The first was spotted inside a baggie of moist potting soil that I put in the refrigerator a couple of months ago. That sprout was attached to a marble-sized, brown yellowhorn (Xanthocerus sorbifolia) seed. Giving the bag a shake brought more seeds to the surface, all with emerging sprouts.

The other sprouts were in a Clementine tangerine box that, last summer, I had filled with potting soil in which I had sown seeds of Nanking cherry (Prunus tomentosa). The box sat outside along the north wall of my house until a couple of weeks ago, when I brought it indoors to warmth.

Without doing time in the cold, whether outdoors or in the refrigerator, neither batch of seeds would have sprouted. They needed, as do many tree and shrub seeds, a period of stratification, that is, time kept cool and moist. After a certain number of hours under these conditions, typically about 800 hours for hardy trees and shrubs, the seeds can sprout unless temperatures are too cold.

I chose my words carefully when I wrote “cool and moist” above; temperatures below freezing contribute nothing to this so-called cooling “bank.” So, outdoors, those Nanking cherry seeds put time into their chilling bank this past autumn and during any of winter’s warmer days. If that time hadn’t been sufficiently long, hours in the “bank” could have been topped up in late winter and early spring.

A refrigerator is just the right temperature for stratification, too right in some ways. The consistently cool temperatures there fill up the chilling bank hours quickly, so quickly that seeds collected in late summer and stratified there often sprout in December, which means indoor planting at a time when growing conditions are at their worst. That’s why my yellowhorn seeds didn’t get a good soaking and then tucked into the bag with potting soil in the refrigerator until late November.

Forget about the nuts; yellowhorn is worth
growing even just for its flowers
The yellowhorn seeds came from a tree I planted many years ago. I planted it because yellowhorn was billed as a small, hardy tree with a nut very similar to a macadamia nut. Yes, the nut does look like a macadamia, inside and out, and it’s about the same size. But yellowhorn nuts taste nothing like macadamia nuts. The yellowhorn nuts from my tree are barely edible, roasted or raw.

So why am I so excited about the nuts (seeds) sprouting to give me additional plants. Yellowhorn is a beautiful tree with ferny leaves and drooping, large clusters of purple-throated, white flowers that rival and resemble orchids.

Run-of-the-mill, seedling macadamia nuts are not as tasty as named varieties that have been selected over the years. No named varieties of yellowhorn exist. Perhaps a tasty clone may one day be discovered. Perhaps one of the sprouting seeds in my baggie will grow into a tree that will be the one that bears those tasty nuts. 

Nanking cherry is another story, as far as taste. Like yellowhorn, no named varieties of Nanking cherry exist. But I’ve tasted the fruits, which are small, sweet-tart cherries, from many different plants in many different places over many years, and they all taste good.

Like yellowhorn, Nanking cherry also sports beautiful flowers. Each year in early spring, my Nanking cherry shrubs are drenched in such a profusion of pinkish-white blossoms that you can hardly see the stems.

Nanking cherry stems are hidden behind
the oodles of fruit this plant bears 
Another plus for Nanking cherry is that it is pest-resistant and bears reliably every year. The usual pests of cherries -- curculios, fruit flies, brown rot, leaf spots, borers -- are insignificant on Nanking cherries. And the plant laughs off extremes of temperature: It’s native where winter lows plummet to minus 50°F and summer highs soar to 110°F, and even though the plants’ blossoms open early in spring, spring frosts are never a problem. Did I mention that the plants also grow quickly and bear young, typically a couple of years after planting?

All this is not to say that Nanking cherry could not be improved. Some selection or breeding could slide flavor more towards the sweeter end of the sweet-tart scale. Larger fruit would be welcome. Mostly, the cherries are a mere one-half to five-eighths inch in diameter.

So last summer I collected seeds from fruits that were a little bigger and a little sweeter than the rest. Those were the seeds I planted in that Clementine tangerine box. I’m going to let these plants grow until warm weather settles in spring, then move them outdoors. In 2 or 3 years, I’ll be sampling fruits from these seedlings. I’ll save and plant some seeds from shrubs bearing the largest and tastiest fruits, and plant them. Perhaps I’ll eventually have some better Nanking cherries. At the very least, I’ll have lots of them. 

Thursday, February 21, 2013

It's Bulbing Time


Mar 2: Miami Valley (Dayton, OH) Garden Conference: WEEDLESS GARDENING

Mar 9: Philadelphia Flower Show: FRUIT GROWING SIMPLIFIED


Mar 16, Thetford, VT: FEARLESS PRUNING


April 10, Rosendale (NY) Library: BACKYARD COMPOSTING


April 28, WV Master Gardener’s Assoc (Flatwoods, WV): MY WEEDLESS GARDEN

May 11, Margaret Roach’s Garden (Copake Falls, NY): BACKYARD FRUIT LECTURE (morning), GRAFTING WORKSHOP (afternoon)

May 16, Brookside Gardens (Wheaton, MD): MY WEEDLESS GARDEN


The official start for this year’s growing season, which I count as the day when I sow my first vegetable seeds, will begin momentarily. Actually, the season should have already been underway, as of February 1st,  but I put in my seed order a little late so am tapping my foot and (im)patiently waiting for the seeds to arrive in the mail. That first sowing is, of course, indoors, and the seeds will be onions, leeks, and celery. The most interesting of the three, as far as growing, is onion.

Sowing onion seeds indoors would not be a necessity, except that I want to grow onions that will keep until this time next year and that are reasonably large and that taste good. Onion sets -- those mini-onion bulbs available everywhere in spring -- would be the easiest way to grow onions, but you get little choice of varieties. The best-keeping onions are the so-called American-types, which are relatively firm and pungent. European-type onions are large and sweet, but don’t keep as well.

I’ll soon be sowing seeds of New York Early and Varsity, two American types, and Sedona, a European type. New York early is only mildly pungent, so is good in salad, medium size, and stores well. Varsity has good storage and large size to recommend it. And Sedona, although a European-type, store pretty well; I’ll eat them first. You won’t find any of these varieties as sets in local or mail-order garden stores.

There’s one more wrinkle in my selection of an onion variety. The plants, whether bulbs, seedlings, or direct-sown seeds, grow well, pumping out leaf after leaf, under cool, moist conditions. But as the growing season moves on and the sun stays above the horizon for a certain number of hours per day -- just how long depends on the specific onion variety -- a “switch” in the plant flips that tells the plant to stop making new leaves and start pumping energy to making bulbs. In the South, onions are planted either in autumn or midwinter to mature in late winter or early spring. Varieties adapted there are “short-day” varieties that bulb up when days have only about 12 hours of sunlight. Here in New York’s Hudson valley that would happen sometime in March so even if the plants were outdoors, they’d have grown so few leaves that the bulbs would be very puny.

Northern onion varieties are “long-day” types, not bulbing up until daylength is 15 or 16 hours. Here in the Hudson Valley, those daylengths occur in June. The more leaves my onions grow before then, the bigger the bulbs. I could sow the seed outdoors in April and they’ll grow some before that switch flips on. By planting now, more greenery has more time to develop, and the more greenery on the plant before June, the bigger the bulbs.

A Clementine tangerine box is just the right size for sowing 6 rows of onions sees. Once those seeds arrive (tomorrow, I hope), I’ll fill the box with potting soil, make six furrows, and drop 7 seeds per inch into each furrow. Once the seeds are covered and the box watered, the box needs to be kept warm and moist until green sprouts poke through the surface.

Onions aren’t the only bulbs that should be getting under way around here.

Two big, fat amaryllis bulbs arrived as mailorder gifts a couple of weeks ago. I’m not a big fan of giant amaryllises, so they just sat in their opened box. They’ve been sprouting and even showing signs of big, fat flower buds. I couldn’t torture them anymore so finally potted them up.

Down in my cold basement I dug last season’s begonia bulbs (actually, they are tubers, or thickened, underground stems) out of storage. I tucked them in among some wood shavings in an old aquarium last autumn. In contrast to the big, fat amaryllis bulbs, the begonia bulbs didn’t look like much more than rough, brown clods of soil. Moved to warmth, with the sawdust kept moistened with a bit of water -- too much and the tubers will rot -- those lifeless-looking lumps should sprout leaves, and then, by June, flowers. The appeal of the begonias, which I grew from dust-like seeds a couple of years ago, is that the foliage is attractive and the fire-engine red flowers are, in contrast to those of amaryllis, proportional to the size of the leaves and the plant, and they’re borne nonstop right up until autumn.

Thursday, February 14, 2013

Disease & Smelly Plants

You perhaps missed last summer’s plant plague, which might be back this summer. My garden was spared because last summer I happened not to have planted the particular host plant: impatiens (Impatiens walleriana), that workhorse of the shade garden, one of the few brightly colored flowers that thrive with little sunlight. 

Downy mildew disease was the cause of last summer’s plague, which descended on impatiens throughout much of the northeast and parts of the rest of the country. Leaves of infected plants turn pale green at first, then develop downy, white growth on their undersides, and finally collapse. Stems also can eventually pick up infection. Needless to say, infected plants flower little or not at all.

Impatiens in Puerto Rico rainforest, El Yunque
But let’s look forward rather than wallowing in the past. Downy mildew can be expected this year wherever it reared its ugly head last year. Same goes for next year, and the year after, and . . . the spores survive for years in the soil. Downy mildew might even show up where it wasn’t last year, coming in on infected seedlings (early stages of infection are not very obvious) or on spores which, under good conditions, can travel hundreds of miles.

Downy mildew thrives under cool, wet conditions, so the very least that can be done would be to keep fingers crossed and hope for the best. Even better: avoid watering impatiens late in the day or in the evening, and thoroughly clean up everything at the end of the season. Better still: Grow your own plants from seed and/or grow New Guinea impatiens (I. hawkeri), a resistant species parading under such trade names as Fanfare, Divine, Celebration, Celebrette, and Sunpatiens.

The surest bet against downy mildew of impatiens is to not grow the plant. Not being able to grow brightly colored flowers in the shade need not leaves these areas dark and lugubrious. Consider plants with brightly colored leaves, such as caladium, begonia (which also has flowers), and coleus.

By the way, impatiens downy mildew is caused by a different organism than the ones that cause downy mildew on sunflowers, zinnias, and some other plants, so no need to worry about the disease spreading from or to these plants.

P.U.! What an olfactory “good morning” from amorphophallus, about which I wrote a few weeks ago. At that time, a flower stalk was pushing forth from the top of the bare bulb sitting, soil-less, on a plate. Today, the stalk, 18 inches from tip to toe, finally unfolded its skirt-like spathe up the center of which rose the long, fleshy spadix on which the tiny flowers sit. The whole thing is very eerie and interesting but not particularly pretty.

Having grown the plant decades ago, I knew what to expect, nose-wise, from the plant in flower. So I’ve kept a close eye on it and today my nose trumped my eyes. My remembrance was the plant having the aroma of rotting meat. Todays flower was more reminiscent of a horse barn, but perhaps the plant was just gearing up for its full olfactory show. I took some quick photos, then lopped off the flower stalk and tossed it out the back door. Even my dog Scooter showed little interest in the smelly stalk, the aroma of which is meant to attract carrion insects.

Hugo de Vries and amorphophallus, 1937
About 200 species exist of Amorphophallus, the largest being A. titanum, whose flower stalk can soar to 8 feet high and whose spathe is the size of a small bathtub. This species caused quite a stir back in 1937 when a bulb at the New York Botanical Garden, after growing only leaves for a few years, finally flowered. A photo in the New York Times showed the great botanist Hugo de Vries perched next to the enormous flower. How did he stand the smell?

Anyone who thinks gardening is tough, what with weeds, insect pests, and diseases, should feel for the Helvenstons, who garden in Orlando, Florida. Not that they have more pests there than we have here, but they have a different kind of pest, city ordinances. Orlando’s ordinances dictate sizes (25% of front yard area), heights, setbacks, and other aesthetics of front yard vegetable gardens but nothing -- and here’s the clincher -- about water or pesticide use, both of which have environmental repercussions. The Helvenstons’ vegetable garden takes up -- no, makes optimum use of -- their whole front yard.

If the Helvenstons fail to comply with the ordinances, which at present are recommendations and have to go to the city council for vote, they could face fines of $500 per day. “Our Patriot Garden pays for all of its costs in healthy food and lifestyle while having the lowest possible carbon footprint.  It supplies valuable food while being attractive”, says Jason Helvenston.  “They will take our house before they take our Patriot Garden.”

The fight for the right to grow vegetables -- or lawn or ornamentals or whatever you want -- on your own property has gone national. To join the fight, or for more information, visit the website

Thursday, February 7, 2013

Pruning Begins

Just because I wrote The Pruning Book doesn’t mean that I always go forth boldly, pruning shears in hand, to prune with speed and with total confidence. This realization hit me right between the eyes as I was staring at and trying to figure out what to do with a row of St. Johnswort shrubs billowing like a wave over the edge of my terrace. Any more billowing and that mass of stems would become a tsunami; the hedge had to be reduced -- attractively.

The problem is that the plants are a bit big for the site. I have excuses. There are 400 species of St. Johnswort, varying in stature, and I lost the tag to my original plant from which I propagated all the others in the hedge. The soil in the planting strip used to be weedy and poor. After enclosing the strip in a wall of hypertufa (a mix of cement, peat, and perlite that ends up like volcanic rock) and topping the bed with compost, plants grew better than expected. And the St. Johnsworts were supposed to mingle and compete with potentilla plants in the bed, each showing off its sunny, yellow flowers at various times through summer and keeping the other in check. The St. Johnsworts overgrew and snuffed out the potentillas, so, lacking competition from weeds or potentilla, grew too well.

Lopping all St. Johnswort stems back by half or more would not be a good idea. For the rest of winter, the hedge would look hacked back (which it would have been). Hardly the graceful, if oversized, tapering, arching branches presented now. Come spring, new shoots would burst forth mostly near the pruning cuts, the ungainly result, year after year, being wild, new growth sitting atop increasingly, fat stems.

After some chin scratching, I chose a different tack. First, I shortened everything to about 18 inches. Then I shortened some of those already shortened stems to various lengths, some to as short as a couple of inches long. Simple.

For now, largish wounds do stare out from the hedge, but next year, and in years to come, such wounds will be less plentiful and less evident. This pruning’s most dramatically shortened stems will sprout just a few, lanky shoots. A greater number, but each less vigorous, shoots will sprout from stems I shorten least severely. Moderately shortened stems will sprout a moderate number of new shoots of moderate vigor, how many and how vigorous related to how much the stem was shortened.

The end result -- I’m hoping -- will be a hedge with shoots of various size and vigor originating at various heights within each shrub. Just like a naturally growing plant. Pruning in subsequent years should be easier.

Although this pruning sounds formulaic, it was fraught with decision-making: whether or not to cut and how much to cut, both to achieve aesthetic results now and for the future. Shrubs readily sprout new shoots naturally and following pruning, so I at least am consoled that pruning rarely harms the plant and that mistakes are soon overgrown.

In contrast to pruning St. Johnswort, pruning red raspberries is a no-brainer. All you have to do is follow a 3 step recipe.

Step 1: Cut to the ground any stem that bore last summer. These stems look old, with peeling bark, and still hang on to a few remnants of fruit stalks.

Step 2: Cut down selected remaining canes. If the swathe of plants is wider than 1 foot, berries are harder to pick and, because of congestion, disease is more likely. I cut down any stems attempting escape beyond that swathe and then, within the swathe, remove enough canes so that none are closer than about 6 inches apart. Sturdiest stems are those most worth saving.

Step 3: Shorten remaining canes to about 5 feet in height. This pruning is just to keep stems from flopping around. The height could be more or less, depending on how and if plants are trellised. I leave mine longer and weave the canes together onto a trellis wire about 4 feet from the ground.

Friday, February 1, 2013

Citrus in New York?

Winters have been warmer here for the past few years and, so far at least, this winter is playing out to be the warmest ever. But even the “global warming” cloud has its silver lining. Snow is great fun and cold is invigorating but one of my regrets in living in a cold winter region has been not being able to harvest fresh citrus fruits from outdoor trees. If things keep progressing in their present direction, as predicted, that situation may change.

The coldest temperature so far this winter has been down around 9° F, and three of my citrus plants still look fine. In the ground, outdoors! Technically, they are a citrus relative, Poncirus trifoliata, also known as trifoliate orange. The leaves resemble citrus leaves, the white flowers resemble and have the fragrance of citrus flowers, and the fruits, orange and an inch-and-a-half across, resemble citrus fruits inside and out. Too bad poncirus is barely edible, although it can be squeezed for juice that is diluted and sweetened to make an -ade.

Flying Dragon poncirus
Even if poncirus was not edible, it would be worth growing for its beauty, especially the Flying Dragon variety with its contorted, green (and thorny) stems and leaves.

My three poncirus plants started out as seeds plucked from a fruit on a plant growing against a brick wall in northern New Jersey. The seeds sprout and grow easily. After growing one year in pots, into the ground they went. The first couple of years, winter lows of -10° and -19° killed them back to the snow line. They’re allegedly cold-hardy below zero degrees F., but that hardiness comes with age. Also, the pattern of cold development and its duration affects cold-hardiness. This year, so far, the plants look fine from top to bottom.

Poncirus is close enough to citrus botanically that its been hybridized with citrus to make more edible, albeit less cold-hardy, hybrids. Like the citrange, from the mating with sweet orange, hardy to 5 to 10°F. A few varieties of citrange have been developed, all billed as “approaching edibility” but, like poncirus, making a good -ade.

Not to give up on true citrus -- yet. Probably the hardiest is yuzu, a hybrid of a sour mandarin and the barely edible Ichang papeda (C. ichangensis). Ichang papeda is the hardiest evergreen citrus. (Poncirus sheds its leaves in winter.) So yuzu is a true citrus and it is quite cold-hardy, down to about 10°F. And it is eaten. The great plant explorer, Frank N. Meyer described it, in 1914, “rind full of oil glands, smelling like a fine lemon; segments separating easily; fairly juicy and of an agreeable sharp sour taste.”

Mandarins (tangerines, C. reticulata) are also among the hardiest of citrus, and they taste very good straight up. The deep orange fruits of the variety Changsha are sweet and juicy, and I actually have a potted plant from which I’ve been trying to coax fruit for more than 5 years -- or so I thought.

Today I checked the original bag in which I received cuttings of the alleged Changsha. Turns out the name scrawled on the bag is Changshou, not Changsha. Bummer, I was looking forward to Changsha. Changshou is another hardy citrus-type fruit, actually a kumquat, from the closely related genus Fortunella. Kumquats are cold-hardy to between 10 and 20°F., and are a fruit I’ve grown -- indoors in winter, outdoors in summer -- for many years. 

Meiwa kumquat
Kumquats, like poncirus, hybridize readily with citrus species. Hmmm, why not combine the hardy kumquat with the hardy mandarin? It’s been done, the result of the mating being the Nippon orangequat, hardy to 10°F. and with a mild flavor, if left to hang on the plant long enough, and, like a kumquat, having an edible skin.

Except for poncirus, I’m not really hoping to harvest any citrus-type fruits from outdoor plants anytime soon, perhaps ever. Surviving the depths of winter cold is one thing. The plant also has to be able to ripen its fruit within the growing season. My Meiwa kumquats, for instance, ripen in February, and I expect even a few nights in the 20s would turn the fruit to mush.

For now, then, I continue growing the more edible citrus-type fruits in pots that winter indoors. Still, poncirus, that citrus look-alike will look cool out in the landscape.