Wednesday, September 26, 2007

Fall Isn't Only About Foliage

As summer flowers fade, and October themes of harvest, fall and Halloween predominate, gardens are getting more subdued, and more orange. If your gardening energy isn’t flagging, you could fight this with a huge infusion of late annuals, and almost recreate the riot of color of early July. But for those of us who are over age 25 and eschew the use of stimulants more powerful than coffee, it may be more practical to accept the general trend of softer and browner tones, livening them up with perhaps a few points of late-blooming or long-lasting perennials or shrubs (especially roses, such as the ‘The Fairy’ I showed two posts ago).


Gladioli (the magenta spikes seen at left above) are not very long-flowering plants. Their flower spikes look good generally for just a week or so, which period can be stretched slightly if you deadhead the lower flowers (which bloom and fade first) while the topmost flowers are still opening. They are available in any color, but the yellow-to-red spectrum predominates.

Although they are individually short-flowered, you can plant them at any time from the start of May to the end of June or even into July, and they will then flower reliably, if not exactly predictably, about 2½ to 3 months later (by late July, or as late as right now). Their spiky foliage also looks pretty good and healthy for a long season.

My late-planted (6/29/07) Gladioli are almost peaking today. They did not appear affected by the near-freezing morning temperature we experienced the week before last. Late plantings are of course at some risk of freezing off before they get a chance to bloom. On the other hand, in the absence of hard frosts, cooler daytime weather and shortened days should extend any bloom period.

As seen here, I have a clump of Gladioli in my lawn. Gladioli do not mind the low-fertility conditions apt to be found in an unfertilized lawn. You do need a tough step-on bulb-planting tool to get this effect in turf. I think this feature will work better visually if I put a bigger clump next year. In the lawn they stand up vertically; it can be hard to get Gladioli planted in flower beds to do so. You can stake them, or use any awkwardness as an excuse for cut flowers on the table.

Gladiolus corms are not difficult to overwinter, their skin keeping them in good shape under a range of reasonable conditions (unlike Dahlias, whose tubers can shrivel and die if too dry, or get moldy and die if too moist – of course, Dahlias are larger plants, with a much longer bloom season). Late-planted corms are less likely to build up enough strength in their new corms before frosts shut the plants’ photosynthesis down, but like most bulbs Gladioli are fairly cheap as garden plants go.

After frosts have killed off the foliage (or indeed, right now, for earlier-planted ones which flowered more than 6 weeks ago), dig up the corms (or even pull them up slowly by the stem, if they’re in fluffy cultivated earth). To keep them through the winter you should rinse them off, dry them out for 2 weeks on a tray in your basement or garage, then tidy them up by cutting off straggly roots and pulling off last year’s corms. You can store the corms in a mesh bag or panty hose, hanging them up in a dark cool spot such as in your basement. Only the larger corms are likely to flower next year, but you can also save the numerous smaller corms, to plant out next year in some place like a vegetable bed, to bulk up for flowering the following year.

I’ve met a gardener in this area who regularly left her Gladioli to overwinter in the ground. They came back some years and not others, presumably depending on how hard and deep the ground froze in a given year. If you are going to take this gamble, I’d at least recommend putting about 4 inches of loose mulch over them to increase their chances. (We’re in zone 5b in most of the Northern Berkshires, while most Gladioli are reported reliably hardy to zone 8, with thick loose mulch and a position up against your house making them hardy to zone 6, according to my American Horticultural Society A-Z Encyclopedia.)

Hardy Mums

The most common – if not ubiquitous – flowers at this time of the year include the “Hardy Mums,” a form of Chrysanthemum. One can certainly overdo them, but they are healthy and reliable, and available in almost any color except for blue.

Why are Mums always left in pots? Mostly because they’re cheap enough to treat as annuals. Some are not in fact reliably winter hardy here, although they earn their name by holding up well to early frosts. I planted two in the ground a year ago, giving no special coddling or mulching. One survived into this year, and is just now starting to bloom again. I like its orangey contrast with pinky-mauve Sedum ‘Autumn Joy’ as seen here.

Mums like ideal positions, namely full or mostly sun, and moist but well-drained soil. Whether you intend to overwinter them or not, Mums will do at least as well for now in the ground as in a pot, without the need for the regular watering or fertilizing of a pot plant. They are also more likely to survive the winter if they are planted now, rather than after another month in their pots. The only downside to putting them in the ground is if you would consider a death there a demoralizing failure. But if it’s a plant you would otherwise nonchalantly kill off by leaving in a pot outside, why hold on to such a cautious attitude?

Saturday, September 22, 2007

Last Chance To Plant, Until...

Southview asked me in the previous post:
"I bought a couple of lilac bushes (just stems with a couple of leaves) and they just arrived. Should I stick them in the ground now or pot them till spring then plant them?"

Here's my quick advice:

Stick the lilacs (or any plant you have) in the ground now. Preferably in a spot somewhat sheltered from the wind, but that isn't essential with most lilacs, as they are very hardy (mostly to zone 3 or zone 4; we are in zone 5; there are more tender lilac species, but I don't think anyone around here would be selling them).

The notion of a fall planting season isn't only a marketing gimmick, although in a colder climate like ours, the spring season is a slightly safer one for marginally hardy plants. The heat of summer does provide a real gap between these seasons, even in the Berkshires. But it's late enough in the year for this area that heat stress is no longer a factor.

Certainly by now we're in the fall season here (and the first official day of fall is September 23 this year), and the earlier in the fall you put your plants in, the better established they will be when the ground freezes hard (roots grow even after leaves fall, but not once the soil nears freezing).

Last year I don't believe the ground really froze until about January 10, so even November plantings of Zone 5 plants should have done fine, but you can't count on such a mild early winter. Basically, we have a couple more weeks of likely good planting season, although I might consider an October shrub purchase if the price is radically cheap (like 60% off a fair initial price).

Lilacs are not houseplants. Keeping them in the house in pots is actually more risky than planting them out, perhaps even if you have a cold greenhouse. And keeping plants in pots outside would be the one way cold could kill them. Effectively, being in pots tends to reduce hardiness by 2 zones. I believe that nurseries holding potted trees will bury even the hardiest of them in foot-deep piles of mulch.

I do recommend that, after some cold weather, when the top half-inch or so of ground is frozen, and rodents have found other places to spend the winter, you spread 2 inches of mulch around the new shrubs, keeping the mulch a couple inches from the trunk. The mulch layer is primarily meant to reduce sudden freeze-thaw cycles, but will also somewhat reduce the depth of hard freezing.

Most winter deaths for plants claimed to work in your zone, especially of new plantings, aren't due to absolute cold, but rather to dehydration, as frozen roots can't supply water to a dessicating plant. This is a bigger problem with evergreens, especially broad-leaved evergreens like Rhododendrons (I recommend Wilt Pruf or other antitranspirant spray for new plantings). You should note if there's a fall drought (which isn't as obvious as a summer drought) and if so keep the plants well-watered.

But ironically, good drainage actually helps prevent the frozen-dehydrated problem. Soggy ground freezes solid, while soil with proper drainage has air pores, freezes less deeply, and allows meltwater periodically to percolate in.

Naturally, I have not done extensive experimentation on all of this (i.e., with randomly selected plants and placebos), but am reporting the collected wisdom of botanists, arborists and other authors whose expertise I trust. I have seen Wilt Pruf-treated rhododendrons looking much happier than nontreated neighbor plants, and have noted the tendency of well-drained and amended beds to not freeze as hard as other spots.

[One last tip. Don't fertilize any plants other than annuals now, or after about mid-August for most zone 5 areas. Fertilizing will encourage soft new growth -- which will be killed off in cold weather -- and should be held off until next spring, generally when Forsythia blooms.]

Sunday, September 16, 2007

Cuttings For My Garden

Personally I find nothing more thrilling in gardening than the successful propagation of plants. While growing from seed is pretty good, especially for perennials, taking cuttings of plants is positively magical. It is, after all, cloning.

This year I have taken cuttings from two shrubs. The first is a friend’s red-flowering Weigela, which blooms at least twice each summer, fairly unusual in Weigelas. I don’t know if it’s a known or named cultivar, or a lucky find in a seed-raised plant. (Weigelas aren’t known for great foliage or branch or fruit interest when they’re not in flower, so rebloom is an important feature.) The cuttings were taken in late June. I cut off several branch tips, keeping them in a Ziploc bag with a damp paper towel for a few hours before getting to my garden.

Most of the Weigela cuttings had two leaf nodes. For each, I made a fresh cut just below the lower leaf node, removed the lower leaves, and trimmed back the upper node to two half leaflets (i.e., I cut each leaflet in half). I used a single-edge razor blade, but a knife will do if it is sharp.

I inserted the cuttings in some seed starter mix, in 3-inch Jiffy peat pots, and kept them damp and under a clear plastic cover, with perhaps an hour of morning sunlight each day. Basically a cutting is a race to grow roots before wilting or a fungus takes over, but you can’t try to rush the growth with heavy sun or fertilizer, or you will uniformly fail.

As soon as a cutting starts visibly growing, it is also growing roots, and it can be put where its humidity-sealing cover is removed gradually, perhaps an hour a day for a few days, until it is always uncovered. Once uncovered, you will have to water or mist it daily. And then you put it into successively sunnier locations until it is acclimated to where you want to plant it, and you’ll only have to water when the soil is dry.

As of now I have three strong Weigela plants, which have rooted and more than doubled in size, four more plants whose future is in question, as they haven’t grown and are looking rather tired, and about four which succumbed to rot. (You must throw out any rotting ones lest the fungus or whatnot spread to the others.)

The beauty of cuttings is that with access to a healthy bush it’s trivially easy and cheap to take a dozen of them. And with most plants, most of the time, and a modicum of care, that’s usually enough to guarantee a few successes. If you can get Rootone®, TakeRoot® or a similar hormonal rooting product, that often increases your success rate to a clear majority, but with some plants like willows (various Salix species) you can put a stick into the ground just about anywhere, even upside down, and be almost guaranteed of success. (They are harder to keep alive when rooted in a pot.)

Weigelas aren’t quite as vigorous as willow cuttings, but they are known to be easy, so I didn’t bother tracking down Rootone, which I was surprised to learn is not carried by all garden supply stores and nurseries. Of my three successes, I put two into my garden in late August. The third is in a fairly large (perhaps 5-gallon) plastic pot which I aim to bring inside for the winter and place in a window. Hopefully at least one plant will survive cold, snowfall, and/or neglect (the oversized pot will last longer between waterings), making it to spring, and clear sailing for a shrub.

This year I purchased the rose known as ‘The Fairy’ – a smallish but very healthy, adaptable and long-flowering rose with many small pink double flowers. It is known to root fairly easily, with spreading canes which often layer spontaneously where they touch the ground. The Fairy dates from 1932, and so is not under patent.

On the 13th I decided to experiment with this plant, to see if I would have any success under, if not the worst of conditions, then certainly a half-assed attempt to maximize success -- late in the season, with no rooting powder, and using no cover, relying instead on shade, cooler weather, and the harder wood of later-season cuttings being more resistant to wilting.

I trimmed off a disproportionately long cane (partially seen in the top center of the first photo) and made about ten cuttings.

I had used a gloved finger to pop the thorns off to the side, making the material easier to handle, but while the Weigela had been softwood in late June, this roses’ hardwood cuttings were, indeed, quite hard to slice through with a razor blade. I was almost surprised I didn’t get myself sliced in the process. Note the sticky pad, which is a 3-inch square; a fully prepared cutting is to the left of the pad.

Most of the cuttings have three nodes; some have two. I removed the lower two nodes’ leaves, and half or more of the leaflets in the top node, and inserted most of the cuttings, untreated, into the ground. This was in a very well-drained area, a raised bed, which I had double-dug and amended with compost a month previous when I was planting a (rooted) Weigela. It is important that the cuttings area be such well-drained and yet moisture-retaining material, free of competing roots, loosened, but also firmed down. Ideally, experts such as Christopher Lloyd recommend a mix of 1 part loamy soil, 2 parts peat moss, and 3 parts coarse sand or grit (1/16 to 3/16 of an inch).

Four of the cuttings I inserted along the rim (shaded side) of the large pot with the rooted Weigela in the middle. This pot is still outside, getting morning sun on the Weigela, but it will go inside for the winter.

Certainly these late, unbabied rose cuttings are at greater risk than the already-rooted Weigelas. But even fully rooted cuttings are not as winter-hardy as larger, established plants. Altogether I will be happy if I get at least one Weigela and two roses to survive into next year’s growing season; after all, they cost me nothing (I did use about $6 worth of supplies I already had, as noted). I may put something cage-like on top of the outside plants so heavy snow won’t crush them.

How late in the season can you do all this? Softwood cuttings are best taken by early July, so as to be strongly rooted by end of season. Hardwood cuttings are supposed to be doable even into November. But in that case, you can’t expect any growth or rooting until spring. (The cuttings will probably survive, dormant, since having no leaves that late they won’t be losing much moisture.) The limiting factor then may be frozen ground. You could, if planning cuttings, prepare the ground ahead of time and keep it unfrozen with a thick layer of mulch.

Any questions?