5/31/13: In the garden this week

A vegetable garden in late spring is nothing but promise. We’ve been picking delicious greens for several weeks, the borers have not attacked the squash plants yet, and the fungal diseases have not splotched and distorted the tomatoes.

Here’s what you should do in your garden this week:

— plant tender vegetables such as tomatoes, squash, eggplants, basil, and cucumbers if you haven’t already done so. Every few days, wipe down the stems of summer squash plants to remove the eggs of squash vine borers.

— continue to seed beans, chard, kale, beets, carrots, and turnips as space becomes available. I try to put in at least half a row of beans every couple of weeks to ensure a continuous harvest. Within the next few weeks, I will be pulling out arugula and other greens that have gone to seed, and this will free up some space for summer crops.

— prune spring-blooming shrubs after they finish blooming, and remove spent flowers on lilacs and rhododendrons so the plant puts its energy into making new flower buds for next year.

— when the weather gets hot (and it got very hot this week), I stop planting perennials and woody plants. In general, plants like to make new roots when it’s cool and top growth when it’s warm, so it’s difficult to establish new plants in hot weather.

— we had several inches of rain this past week, so avoid watering the lawn. It really, really doesn’t need it. And the more you water, the more you will have to mow.  The only things that need watering are newly established plants, which need supplemental watering for a whole season or, in the case of trees, sometimes longer.

Enjoy the first taste of summer and, especially, the expectation of summer tomatoes and basil.

The names of plants, and why they matter

All living things have scientific names made up of two parts: genus and species. That’s “genus,” not “genius” or “genii.” A genus is a group of closely related species. It’s an organism’s surname (Chinese style): we are Homo sapiens (genus Homo, species sapiens). Many of the names we use to refer to familiar plants are actually genus designations: echinacea, viburnum, aster, rudbeckia all refer to a number of closely related species.

If you’re interested in learning about plants, genus is a useful level of classification. It’s fairly easy to learn to recognize a dogwood (genus Cornus) or a maple (genus Acer) and to learn to distinguish members of that genus from other plants: most dogwoods are shrubs or trees whose smooth leaves have parallel veins, most maples are trees that have 3- or 5-pointed, deeply serrated leaves.

Knowing a plant’s genus gives you some valuable general information about its appearance and growth habits, but it does not tell you what kind of site is most appropriate for that particular species. Within a genus, you can, and you generally do, find species adapted to widely varying conditions. There are viburnums and dogwoods adapted to wet, sunny sites, to dry, shady sites, and to everything in between. So to understand if a plant is right for your garden, you must know the species.

Scientific names are useful because they’re much more precise than common names. If I say “viburnum,” I might mean any one of a dozen native trees and shrubs or any one of a hundred species worldwide. But if I say “Viburnum dentatum,” I can only mean a mid-height shrub with white flower cluster, toothed leaves, and slender stems that lives in wet places throughout the eastern United States–a shrub that will bloom within the next week or so in northern New Jersey.

Plants sometimes have names that include the symbol “x” or words in quotation marks. A plant with a name such as Viburnum x juddii is a hybrid–it was created by crossing plants from two or more closely related species. I tend to avoid hybrid plants, because they are often sterile, and I want pollen to attract butterflies to my garden and fruit to attract birds.

Single quotation marks in a name indicate that a plant is a cultivars (for example, Viburnum dentatum ‘Autumn Gold’). A cultivar is a plant that has arisen in cultivation and been selected for some desirable characteristic, such as larger flowers or cold tolerance, that can be maintained in propagation. Cultivars will cost more than pure species, and it is often illegal to propagate them (kind of like a copyright on a book). They often have undesirable characteristics along with desirable ones. For example, extra-large flowers may mean that the plant can’t stand up straight. Or extra-bright colors may mean that pollinators can’t recognize the flowers. Again, I stick with species whenever possible.

In this blog, in all my writing, in my own garden, and in my horticultural practice I recommend using pure species of plants that are native to this part of the United States. Seek out nurseries that label plants precisely and correctly, and you’ll be more likely to wind up with the right plant for the right place.

How about growing this: Penstemon

Penstemon digitalis is always the first prairie plant to bloom in my perennial border. Lovely, isn’t it? It’s also well-behaved and completely carefree, so I really, really don’t understand why you don’t grow it. And I’m pretty sure you don’t, because no one I show it to has ever heard of it.

There are three or four native penstemons; most of the others have purple flowers. This species, Penstemon digitalis, also called smooth penstemon or smooth beardtongue, has white flowers, sometimes with purple throats. It is the easiest penstemon to grow and the longest lived. All it needs is full sun and reasonably well-drained soil. Individual plants gradually grow wider and fuller, but the height never exceeds 3 feet. The plants self-seed happily but not aggressively, and they do not spread by rhizomes, so they are easy to keep in check.

Penstemon begins blooming at the very end of May or the beginning of June and keeps going through July. By that time, many prairie plants are in full bloom, so it’s a nice bridge from spring to summer.

There is a naturally occurring form with burgundy leaves. In my garden, some of the seedlings come up green and some red, but all the plants I originally purchased (long ago, from Prairie Nursery in Wisconsin) were green. This next picture shows two plants, one green and one burgundy, growing next to each other. Notice how nice and straight the flower panicles stand. The bright green foliage in front belongs to a Rudbeckia that will be taller than the Penstemon in a month or less, and to the left of the Penstemon you can see junegrass (a native prairie grass, Koeleria macrantha), about to bloom.

To me, when penstemon blooms, that means it’s summer in my garden. Get yourself some summer as well.

How about growing this: ninebark

Ninebark, Physocarpus opulifolius, is in bloom right now, and I’ll bet anything you’ve never seen it. In fact, I’ll bet you’ve never heard of it and that when you first saw this picture, you thought it was spirea. If so, you made a good guess, because ninebark and spirea are related, both members of the rose family. But the spirea you were thinking of was an Asian species, and ninebark is native to the mid-Atlantic and mid western United States.

Ninebark is a pest- and disease free shrub that is adaptable to a variety of conditions. I grow it in part and full sun; my site is dry, but Dirr’s Encyclopedia of Trees and Shrubs says that it grows wild along stream banks in Virginia and North Carolina and occurs north to Quebec. If you have a problem spot where nothing seems to do well, try it there. It is deciduous, and the leaves are three-lobed, rather like maple leaves.

Ninebark will grow up to about 12 feet high and wide, but you can easily keep it  smaller by removing the largest canes. Allowed to grow to its maximum size, it would have a mounded shape and would make a nice specimen plant for a mid-size front lawn; kept smaller, it makes a lovely hedge, which is now it’s used in the photo above. You could use it in a mixed hedgerow with other native shrubs such as grey or silky dogwood and blueberries. If you are partial to deep red or gold foliage, cultivars with those colors are available (so you could plant it instead of the red form of Japanese barberry, which is a highly invasive plant). Some individual plants have pink flowers, which are quite lovely. The fruits are  usually tan or green, but many plants have red fruit capsules, which are very attractive against the yellow fall foliage.

But I’ve saved the best for last. Ninebark flowers are a magnet for red admiral butterflies. I sometimes see upwards of a dozen on a single plant. Wouldn’t you like to go right outside your house and see this on a sunny day in May?

The evil forces that surround us (or, baby bunnies)

By “evil forces,” I am of course referring to baby bunnies. You’re a gardener, so you knew that, right? These horrible pests are now about the size of my fist, and there is one hanging out in each of my perennial beds.

Here is a list of the native plants rabbits most  like to eat, in order of preference, as I have discerned it over 20 years of gardening on this spot: asters and phlox of all species (tied for first place), boltonia, rudbeckia, Culver’s root (Veronicastrum), spiderwort (Trandescantia), coreopsis, liatris, and, of course, strawberries (only the fruit). I didn’t even include echinacea, because it’s been years since I’ve been able to keep one alive, they love it so.  We also have deer and woodchucks, among other wild critters, but the rabbits, due no doubt to their to propensity to multiply like, well, rabbits, seem to do the most damage.

However, I am smarter than they are, so I do manage to grow all these plants, with varying degrees of success from year to year. Last year was the worst I ever experienced. The preceding winter was exceptionally mild, so relatively few critters had been killed off. They repeatedly ate perennial plants to the ground, so not a single phlox or boltonia  or Culver’s root bloomed. I did get a few asters, mostly from plants in pots or tucked far back in the borders. But last year was very unusual.

This past winter was quite cold, and this season is more typical: the rabbits are enjoying my garden, a bit more than I think they should, but most plants are doing fine. (And note that even the plants that didn’t manage to bloom last year are back this year on their own–I didn’t replant them. Native perennials are tough.)

I do have several strategies for minimizing rabbit damage to perennials, and I’ll share three important rules with you. But first, here’s how I figured this all out: My first foray into native plant gardening involved planting 7 grey dogwood shrubs across the backyard. All were immediately eaten down to the ground. My next attempt involved many more plants–upwards of 100 woody plants, all very small. Most survived. So Elaine’s first rule of outwitting furry critters is to plant lots of plants and many of each species.

Those 100 plants were scattered randomly, not planted in neat rows or groupings by species. That’s now nature does it, and I like the random look. But it also helps outwit the pests: if a rabbit likes phlox, I want to make it really hard for him or her to find all the phlox. And these furry guys aren’t really that smart–they tend to return to the same plant over and over, leaving the rest of that species to grow undisturbed. So Elaine’s second rule is to mix it up.

Note that some plants don’t get eaten. These include milkweeds, penstemon, native grasses, sundrops, ferns, and columbine. I tuck the most attractive plants among these distasteful ones as a kind of camouflage–a couple of phlox in the center of a group of milkweeds. So the third rule is to use the critter’s tastes to your advantage.

Notice that I haven’t mentioned poison, or traps, or dynamite, or firearms, all of which have crossed my mind (they are illegal here). I have tried repellents, including our own dog, who spends lots of time in the backyard, but none seem to work. Rabbits invariably make their nests just outside the range of the dog’s chain, and they are not repelled by the scent of fox urine or dog hair or anything else I am aware of.

And then there are the critters in the vegetable garden and herb plot. Don’t get me started.

5/24/13: In the garden this week

Memorial Day weekend promises to start out cool and rainy but to improve by Monday; next week will gradually heat up. In this climate zone, Memorial Day is the traditional time to plant warm-weather annuals and vegetables. Here are some tips for what to do in northern New Jersey this holiday weekend:

— if the forecast pans out and the weather hits the 70s by Monday, go ahead and set out your tomatoes, eggplants, and squash. I know you can’t wait any longer, and neither can I.

— similarly, if you plant annuals, it’s safe to plant the more tender ones such as begonias. Avoid impatiens this year, which are subject to a new and fatal fungal disease.

— continue to plant perennials and herbs until the weather really  heats up. I love to fuss around in my perennial gardens, moving and dividing plants to fill gaps, contrast colors, improve bloom sequence, or whatever, but I generally stop by the end of May. It’s usually so warm by then that the plants need too much water to recover.

— continue to prune spring-blooming shrubs and trees such as forsythia and rhododendrons; do not prune summer bloomers, or you will cut off this season’s bloom. Now that shrubs and trees have fully leafed out, it’s safe to do nonremedial pruning once again. And now is the optimal time to prune evergreen hedges–while they are in active growth.

— remove spent blooms of lilacs to improve plant vigor and safeguard next season’s flowers

— weed, weed, weed! All this rain will cause the weed seeds to germinate and the existing plants to grow luxuriantly. It’s easier to weed all the time and a little at a time than to let the weeds get out of hand and have to do it all at once. And start soon–weeding is easier when the ground is wet.

— with all this rain, you should certainly not need to water your lawn or anything else

— one traditional lawn-care regimen calls for three applications of fertilizer per season: on Memorial Day, Independence Day, and Labor Day. So if you absolutely can’t live without fertilizing your lawn, go ahead and do it (but please, please use an organic fertilizer). But you’d be much better off not fertilizing at all and using more sustainable lawn-care methods: let the grass grow at least 3 inches tall to maximize photosynthesis, and use a mulching mower so that the clippings fall back on the grass and provide free fertilizer (this regimen requires much less money and work and is better for the lawn and for the environment).

And don’t forget to enjoy the garden this weekend! (To me, all of the above is highly enjoyable–I hope it is to you as well.)

The law of unintended consequences, or serendipity

Today my son sent me a link to an article about a fascinating example of the law of unintended consequences at work. It seems that all that Greek yogurt we’ve been devouring has created a huge waste problem: the whey that’s strained off the yogurt to make it thick is highly acidic. It can’t simply be discarded, because it pollutes both land and water, so no one knows what to do with it.

Life is full of unintended consequences, and gardening has its share: Spray the aphids and kill the ladybugs. Plant a tree and shade the perennials. Turn over the soil and expose the weed seeds, allowing them to germinate.

Our interactions with the environment lead to much bigger and more serious unintended consequences: Pave over a field and create a flooding problem. Plant genetically engineered crops so you can use herbicides to kill weeds and destroy the only food source for monarch butterflies. Burn lots and lots of fossil fuels and overheat the planet.

Sometimes, however, unintended consequences are pleasant ones–we call those serendipity. Gardening is full of these as well. Leave a  narrow strip of lawn unmown and allow a mini-forest to create itself (more about that in a future post). Allow some weed seedlings to grow and welcome an aster species new to your garden. Plant native ginger next to Canada anemone and discover a way to control the spread of an aggressive species.

Lots of happy garden surprises arise from sloppy mowing or weeding. When I didn’t weed one of my perennial beds carefully enough, this lovely white daisy fleabane, a native annual, popped up in the midst of orange butterflyweed and pink bergamot:

Garden mindfully, and help ensure that most of your surprises will be happy ones.

Eight perfect peonies

I planted three peony bushes over 15 years ago, white, red, and pink. I would never plant peonies now–they’re not native (although they do not become invasive). I never amend my soil, so I’ve never added the enrichment–bone meal and whatever–that peonies are supposed to need. Over the years, two of the bushes disappeared. But the site gets full sun, and the soil has improved over the years, because native perennials create rich, black soil. So this plant has hung on, and every year it’s made one or two luscious, perfect, fragrant blooms. But this year, there are eight. I cut them today and brought them into the house to perfume the kitchen.

Enjoy.

How about growing these: Native perennials for dry shade

As a horticulturist, one of the concerns I hear most often is “But my yard is so (fill in the blank here: shady, or damp, or dry, or hot, or whatever) that nothing will grow.” Well, there is no spot on this planet where nothing will grow, and very few where green plants won’t grow. Whatever the constraints of your site, many, many beautiful native plants are adapted to grow and thrive there. This post is about dry shade. Check back for other posts about other types of “difficult” sites.

Let’s start by thinking about our native habitat here in northern New Jersey. What kind of ecosystem is shady in nature? The forest floor. So it follows that most, if not all shade plants evolved in nature as understory plants.

This is a picture of the shadiest part of my garden. It’s planted on the north side of a group of trees, so it gets only occasional dappled sunlight. And it’s a very, very dry site, with sandy soil (I don’t have a sprinkler system, and I water only in extreme drought). But notice how lush and cool it looks. It’s thickly planted with coralberry (a small shrub), ferns, and a number of flowering perennials: Canada anemone, wild ginger, tiarella, white snakeroot, and asters. The tiarella and ginger bloom in spring, the anemone in early summer, and the asters and snakeroot in fall. All these plants are readily available and foolproof to grow. Some of them are “volunteers”: I didn’t even plant them. They are simply natives that arrived on their own.

Each of my shrub islands includes shade-loving perennials. (These “islands” stretch across the front of my property and are planted in the only parts of the front lawn that aren’t completely shaded by two large Norway maples.) The perennials grow at the front of the islands, along the sidewalk, and they get a few hours of direct sunlight in the early morning or late afternoon. So they get more sun than the shade garden pictured above, and they support a greater variety of flowering plants.

Columbines dominate here–so many I have been begging gardening friends to take them off my hands. There are also native geraniums (the pink flowers), asters, wild ginger, corydalis, tiarella, and heuchera. Again, there will be flowers for most of the growing season–the columbines will be in bloom through much of the summer, and the asters will take over in late summer and fall.

I grow some plants that normally grow in wetter sites–all plants thrive in a range of conditions. An example is false Solomon’s seal, which is in bloom right now in two of my shade gardens but generally grows in wet sites.

Lovely, isn’t it? If the rabbits don’t eat all the flowers, the plant will produce a cluster of bright red berries in early fall. Notice the variety of foliage around it–wild ginger on the lower left, asters, heuchera and tiarella at top and center.

For more detail about some of these plants, see my earlier posts about tiarella and columbine. And do consider seeking out some of these lovely natives for your own backyard habitat.

How about growing this: Sweetshrub

Sweetshrub (Calycanthus floridus) is a mid-height shrub native from the southern United States up through the mid-Atlantic states. It is particularly well adapted to shady, damp sites. It has lovely deep red flowers in late spring that smell like strawberries and beautiful, glossy foliage (I took this picture today at the Thielke Arboretum in Glen Rock, NJ).

Sweetshrub is one of those charming old-fashioned plants that people used to grow but that are now disappearing. It is a nice shape and size–usually about 6 feet wide and tall, and easy to control. It is pest- and disease resistant and easily transplanted. If you have a site that’s too wet or too shady for most common landscape plants, take the trouble to seek out sweetshrub. You will have a beautiful plant for your landscape, and you will help bring diversity back to out suburban backyards.