Category — Plant care

In my last post, I discussed Peter Henderson’s 1875 greenhouse/hothouse plans for the wealthy. But Henderson deserves credit: he didn’t just write for the rich, he wanted people of every income to have a chance to grow a plentitude of houseplants and exotics.

After he’s exhausted himself on the subject of the Ideal Greenhouse, his Gardening for Pleasure continues with ideas for attached greenhouses and greenhouse-pits that need no artificial heating to hold the plants you would keep in a cool greenhouse. It’s advice that modern half-hardy and tender plant growers might use, since rising fuel prices make heating a greenhouse an increasingly expensive proposition.

The attached-greenhouse method only works in areas with relatively mild winters; Henderson wrote from Jersey City Heights, where it freezes and snows, but not inordinately. (New Jersey, whose car licenses still read “Garden State”, was at that time a huge market-garden area that served the massive population of New York City.) A small greenhouse attached to a heated building, properly constructed, says Henderson, will keep plants going in places where the temperature doesn’t fall below 25 degrees F (-4 C). It needs to be tightly glazed, and shielded from the north and north-west (if you’re below the equator, change the directions accordingly).

The pit greenhouse (which seems to be a kind of glorified sunken cold frame) is even better, Henderson says. “This is formed by excavating the soil to the depth of from 18 inches (45.7 cm) to 36 inches (91.4 cm), according to the size of the plants it is intended to contain. A convenient width is 6 feet (1.83 meters)…and of such length as may be desired.” He cautions that the ground must be dry enough that water won’t seep into the pit, and advises walling the sides of the pit  4  (10.2 cm) to 8 inches (20.3 cam) high with brick or planks.

“The back wall should be raised about eighteen inches (45.7 cm), and the front six inches (15.2 cm) above the surface, in order to give the nursery slope to receive the sun’s rays and to shed the water.” If glass is laid on top, and light shutters or half-inch boards  laid on top of the glass every evening, “it may be used to keep all the hardier class of greenhouse plants, even in localities where the thermometer falls to zero (-18 C). ”

While plants in such cool greenhouses won’t thrive lustily, they will be ready to go at the first sign of warm weather. That way, you wouldn’t have to grow out tender or half-hardy plants from small slips every year, or buy them new.  If I bestirred myself to make such a pit-greenhouse, I could  have the large collection of scented and flowering geraniums I’ve fantasized about, or keep beautiful brugmansias over winter reliably, and flower them before frost. I wouldn’t have to beg friends to babysit my houseplants when I go away in winter, either. (I don’t have central heating, so if temperatures fall below freezing, my houseplants turn to mush.)

Older technology has a lot to teach us. While we may not have the stay-at-home lifestyles or cheap help of past eras, many of these antique ideas make better sense than energy-eating options we are offered today.

It’s the time of year when I visit old haunts, figuratively and literally. One of the oldest (literally speaking) is the Providence Atheneum, a library that’s been around so long that all the reading desks and chairs are antiques, and gardening books from the 1800s are still on the shelves, waiting to have their depths plumbed by people like me.

Plumbing, it turns out, is the mot juste. On this year’s expedition, I was surprised to discover that radiant floor heating was the heating system of choice for hothouses in 1841.

But as I started writing this post about it, I remembered a long-ago visit to the Alhambra, where I found radiant floor heating systems much older than that. Eight hundred years ago, the architect had caused a bath area to be built, and I remember the guide saying that the hot water was piped under the floors above, as heating. (Why is it that I can remember this comment from over thirty years ago, but I can’t recall the name of someone who introduced themselves five minutes earlier? Memory is indeed like a sieve, as a friend of mine used to say.) Since the entire palace is out of stone, the heating was probably welcome in the winter.

I am not sure if radiant floor heating was invented by the Arabs, but it seems likely. They were leaders in water engineering, likely due to their development of mathematics. I still remember the water in the gardens of the Alhambra, because they amazed me: though the place was neglected and crumbling around the edges (it was the very end of the Franco regime), all the fountains and pools and watercourses still worked: they had been designed to run on gravity alone, no pumps needed. On one staircase, where railings would normally have been, there were channels in the tops of the sidewalls, cascading water down to yet another pool and fountain. The flumes in my goldrush area sent timber from the mountains to port cities on the same principle, but they didn’t last nearly as long as the watercourses of the Alhambra gardens.

If anyone knows the history of radiant floor heating, or cares to speculate, I’d be interested to read your comments. But for now I will jump ahead to 1841, and Robert Buist’s The American Flower Garden Directory.

Garden writers of the mid-eighteen hundreds usually ran nurseries. They also bred plants, traveled long distances to see what other breeders were doing and to find new stock to introduce into their lists and breeding programs. Any aspect of gardening was their purview; there was much less specialization than there is today.

That’s because in 1840s U.S., gardening and plants were undergoing a huge boom. For the first time, the newly monied middle class could afford the ornamental plants and gardens that had been a rich person’s privilege in the century before.  Farmers wanted to know what the latest crops and plant techniques were. Literacy had become common, so there was a large readership for the books nursery owners began putting out, books that covered everything from the poetic values of tilling the soil to how to deal with the Rose slug, one of the catastrophic insect invasions of the 1800s.

Hothouse building was definitely on the agenda, and in The American Flower Garden Directory,  Buist tackles the construction of hothouses and greenhouses. He describes the siting of the hothouse: “…set the front directly to the south. Any deviation from that point should incline to the east.” And he gives a detailed description of the heating system.  “As workmen are not generally conversant on the subject, nor yet understand the effect or distribution of heat in these departments, we will give minute details on their construction.”

Coal- or wood-fired furnaces were the basis of the heating system  (wood-fired furnaces had to be built twice as big as the coal ones). The cheaper way was to run flues from the furnace through the greenhouse.

“Where capital, taste, and practical science can be united, a more elegant disposition of heating conveniences can be adopted: an excavation should be made for the flue to pass along under the pathway, which pathway may be a casting of iron, or wooden slats, fancifully put together, and at least six inches above the flue.”

But the flue system created problems with smoke and coal gas–dangerous to humans as well as plants. By adding a small boiler to the furnace (he recommend a size about 2 feet (about 61 cm) by 2 feet, and 4 inches (10.2 cm) wide), hothouse owners could have fumeless heating that was better for them and the plants.The boiler was built of cast iron or copper, with a zinc or copper lid. Two pipes were attached to the boiler, one to run hot water through the flues, the other to take the cold water back to the boiler for reheating–a simpler version of the way a boiler works in a steam-heated apartment building.

Clearly, it was the day of different manufacturing methods and abundant cheap skilled labor. Buist expected the incipient hothouse owner to easily find workmen who could build not only the boiler and the plumbing system, but the many wooden frames needed for the 6 by 6 inch (15.2 cm) panes of glass he thought were ideal. But a handy person today could easily rig a similar system for a hothouse, using modern materials.

Next post: How to Heat Your Hothouse: 1841 and Later

References: 

Robert Buist, The American Flower Garden Directory, Philadelphia, Carey and Hart, 1841

Great Buildings website

Years ago, I read something in a Dave Wilson catalogue that changed my understanding forever: cold air is like water. It sinks.

Since heat rises, this makes sense. (Cold air molecules are more tightly packed than the molecules in warm air. This is what makes cold air heavier. ) These physical facts make a lot of difference to your plants.

If you live on a slope, like everybody in my area does, you can imagine the cold air running down it just as water does. If there are depressions in the ground–bowls or valleys–the cold air will pool there.  If there’s a steep downslope, the cold air will keep on flowing until it finds a place to rest.

When you understand how this air flow works, it’s easier to take advantage of it–or to mitigate it, if it’s a problem. Cold air can back up behind houses and fences, the way water gets backed up in a dam.  (Check the bottoms of fences, hedges, and walls for frost; if you find it, that’s a sign that this may be happening in your garden.)

All this can mean the difference between frost and no frost, which can mean the difference between a dead plant and a live one, or a bearing plant and a fruitless one.  In my area, almonds (and often peaches and plums) don’t bear, because their flowers are way too early for the climate. They bloom, frost hits, boom.

Some people recommend planting these marginal early-blooming trees on a north slope: that way their sap stays cold and sluggish for awhile longer, and they bloom later, maybe late enough not to get frostbit. We live in hope.

If you allow for ‘drainage’, you can warm up those areas: an opening along the barrier will act as a kind of sluice, letting the cold air drain down the slope, and keeping the planting area by the barrier marginally warmer.

Even people who live in flat areas generally have some contours in the ground; dips and streambeds surrounded by trees; a slight grade to the ground behind the house. This allows cold air to back up in the same way. (Since it’s been a long time since I’ve been in a flat place, maybe someone else can answer this question: does a flatter gradient mean fewer degrees of frost, or not?) Just look at your ground and imagine water flowing over it, or a big rainfall. Where would the puddles and pools be? These are your cold spots.

Besides “draining” your cold spots, you can also just avoid them when you plant something that thrives on heat, or really should be growing in a warmer climate. I’ll have to test this, but it seems possible to me that it also works the other way around: if you have a plant that really prefers a cooler climate than the one you’ve got, doesn’t it make sense to try putting it in the cool spots?

Anyway, back to mitigating cold–besides draining, you can do it in the time-honored way, by wrapping plants in burlap and bundling them up with leaves, pine needles, or straw. Or, you can do it the modern way-with a spray that protects leaves from sunburn, or with hot caps, water walls, frost blankets, and other coverings.

Another possiblity is using passive solar heat by putting up a west-facing stone or concrete wall. The wall will absorb the sun in the day, and release it gradually at night.  As long as the wall is “drained”, it will keep plants next to it just a little warmer . Warning: if you are in the shade (or in a cloudy climate) it doesn’t matter what direction the walls face; they will always be cold and clammy. There’s nothing quite as chilling as really chilled stone.

If you’ve played with this idea in your garden, I’d be interested to know how it worked for you. I don’t care if it was a success; I just want to know what you learned.

References:

ancient Dave Wilson catalogue, since buried in the archives (read: piles of printed matter)

and from my local nursery: Weiss Brothers Master Nursery newsletter, Nov/Dec 2008

I have no-name chrysanthemums, the ordinary garden type: one in a satisfying deep red, another in yellow-brown tiger shades.  And very grateful I am for them.

But I can’t help liking some chrysanthemums them better than others. The ones I’m particulary attracted to are spoons and quills.

Quill chrysanthemum petals roll up like tiny tubes–the flowers at the top of this post.

Spoons have petals that widen and dip at the end, like (as you might guess) spoons. Here’s a picture of ‘Emperor of China’.

The shape of the petals is general theory, of course. In actual life,  not all of the petals make these perfect forms. But enough of them do to change the personality of the flower.

I have only one each of spoons and quills; for some reason, these varieties seem to be less popular than others. My quill chrysanthemum is nameless, even though I bought it at a good local nursery. As you can see, it was in gorgeous flower when I got it, and I enjoyed it on my porch and in the vase for a couple of weeks.

The spoon chrysanthemum, ‘Emperor of China’,  is a longer-lasting relationship. I got from a White Flower Farm catalogue some years ago. It has taken quite a bit of abuse–drought conditions, semishade–and still flowers. Its flowers last, I swear, a month in the vase–and they’re quite beautiful on the plant as well. The foliage is a  clear green, and some of it turns brilliant red when the weather cools.

In my researches on the Internet, I found out why my ‘Emperor of China’ won’t  give the abundant bloom my nursery-bought  (and anonymous) quills do: I didn’t pinch them. Pinching means taking off the growing stem tip and the first set of leaves, starting from the time the new growth is four to six inches (10.2 to 15.2 cm) long, and stopping in early summer. This allows the stems to branch out and form more budding stems; you stop the pinching in early summer in order to avoid decapitating nascent flowers.

While I rather like the exploded-fireworks look of my biggest ‘Emperor of China’, and the happy juxtaposition of its pale-pink blooms flopping on  grey-green lavender leaves, it would be fun to have more flowers, so I could cut more bouquets. Sun is also another big factor in getting flowers; since I moved the ‘Emperor’ where it gets a bit more sun, it has definitely filled out. But in less-than-ideal situations where it gets only a few hours of light, the Emperor’s shade-skinny length can be slipped in amongst other plants and still give you a few rewarding flowers.

Chrysanthemums were imported from China into Japan somewhere around 710-793 CE. They were brought in as medicinals-they are still important heat-clearing herbs in Chinese medicine-but the Japanese rapidly began to practice their horticultural magic, and soon came up with many breeds and colors. Chrysanthemums make fantastic displays in seasonal festivals in Japan. Their categories for chrysanthemums are different than the European ones, but ours are most likely derived from theirs.

It’s not easy to find spoon and quill chrysanthemums. I know. I’ve looked for them locally, in catalogues, and in pretty exhaustive searches on the web. If anyone has suggestions as to where I can get more of them, I’d be grateful. Meanwhile, I’ll just keep on enjoying the ones I have.

References/more reading on chrysanthemums:

Human Flower Project  - Masachi Yamaguchi’s very interesting writeup on chrysanthemums, gardening, and changing Japanese culture

Bluestone Perennials catalogue, spring 2008

By googling “chrysanthemums”, you can find and download .pdf files from Purdue U,  Cornell, Reiman Gardens, and Utah State–all great resources for horticultural information.

One of my garden correspondents from the UK writes that Prince Charles has given up on planting tens of thousands of tulips every year along the drive at–I forget which dwelling. Instead, he is substituting fritillaries, which come back year after year.

What a lot of people don’t know is, that if you plant the right varieties, tulips are very likely to come back year after year. Most of the ones that come back are species tulips (types that are selected from the wild and cultivated), so they don’t look like the typical florist’s tulip. But they can be appreciated on their own merits.

There’s a caveat here, though: no matter what variety of tulips you plant, if they don’t have good drainage (especially in summer, when they would have a dry spell in their native haunts), tulips will rot instead of flowering.

That taken care of, here are categories of tulips with a good return rate.

Fosterianas or “Emperor”  - Purissima, or White Emperor, is the tulip at the head of this post; it’s the size of a typical garden tulip.  One of my tulip books says they had a stand that lasted twenty years; I had a stand for several years, until I dug it up; they didn’t like the new location as much.  ‘Sweetheart’ and ‘Apricot Emperor’ show every sign of lasting as long, but ‘Flaming Purissima’ went down for the count after one season with me (twice). ‘Red Emperor’ is a selection of the wild species, so it should be persistent–but I haven’t grown it.

Batalinii  - The tulips above are the ‘Apricot Jewel’ variety–there are several of these tall, species-like tulips in various shades of yellow, peach, and rose. In full sun they are about as tall as most garden tulips, but the flowers and stems are much slimmer. In semi-shade they flop rather appealingly on whatever other foliage you have going on.

Greggi - These are short tulips with mottled foliage and many varieties of color in the rose/pink/white/yellow spectrum. They bloom in tulip midseason.

Kaufmannia - These early bloomers are also known as water lily tulips, because their short-stemmed flowers open out like stars. The flowers are disproportionately large for their stem size, and come in various hybrids in the red-and-white spectrum.

Cluisana-type  -  A real clusiana is hard to find, but it’s easy (and cheap) to get ‘Lady Jane’, below. These trouble-free tulips are about ten inches high, and last well in the garden or vase.

Be sure to check out the species section of your bulb catalogue (or nursery) for more possibilities. Species bulbs are usually cheap, so it doesn’t cost much to experiment a little.

Some other older garden varieties of tulips seem to come back well, too: ‘Prinses Irene’ and ‘Insulinde’ have been good repeaters for me. ‘Crème Upstar’ was for a while, then petered out.  If anyone’s had good results getting other varieties of tulips to come back, I think a lot of us would like to hear about it–maybe even Prince Charles.