At least in theory this is what's happening. The end of May is Come to Jesus time for gardeners. I can no longer kid myself that the columbine might have reseeded itself, and that the special fern I got last summer is just slow to emerge. It's time to apply the cold eye of judgment and take stock of what's thriving and what's failing. The next step is to figure out why things aren't going well. Here are the most common culprits:

Shade- In our region many gardeners chase the sun. A sunny garden can become shady in less than five years as nearby trees grow up and out. If perennials like iris and Salvia and shrubs like roses aren't getting at least five hours of sun every day, they will become weaker over time, give poor flower performance, and be more susceptible to disease. Rearranging these plants in a sunnier spot (cheap) or trimming and/or thinning trees (expensive) will bring a sunny garden back to vigor.

Plant selection- before you blame yourself for not being a good gardener, do a background check on the plants that aren't doing well. Certain plants are magnets for disease and can be very difficult to grow in our climate. Hollyhocks get rust in about two seconds, and some varieties of zinnia, phlox, and bee balm are very prone to mildew. The biggest dog has to be the hybrid tea rose, which is virtually impossible to grow under regular garden conditions. If you suspect you have plants in this category, throw them in the trash (don't compost.)

Soil- This is the biggest factor in plant success, and the most variable. Good gardeners are mostly good soil engineers, and understand that most plants like soil that is fertile and well oxygenated. Ideally, there shouldn't be any bare earth in a garden. Without a covering of plants, compost, or mulch, soil loses its nutrients and also becomes compacted by raindrops, surprisingly enough. If you've recently had construction, tilled your garden, or had major tree work done, your soil is also probably compacted. Applying gypsum, a naturally occurring mineral, will loosen compacted soil if it's done annually for three years. And although plants will be slower to establish in compacted soil, eventually the roots will break through the compaction and allow much-needed air and water space between soil particles.

Also, soil will become depleted over time, so organic matter should continually be reintroduced. Once mostly composted, leaves and household plant waste can be added back to the garden; no need to dig it in, just spread it around the plants. Heavy feeding plants will benefit from applications of organic fertilizer. And (my opinion here) all plants do better with the addition of some kind of animal manure. The cheapest and least smelly is dehydrated chicken manure, which can be applied a few times in the growing season. By adding compost and manure, I've greatly improved the terrible soil in my garden over the past two years, and it's looking much better.

Although there are hundreds of other reasons plants can languish, these are the most common. And the good news is that all these problems can be fixed relatively quickly, so you can get your garden on!

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I'm happy with what I see, except for all the weeds. When I started planting my garden a few years ago I made it too big, and despite the gobs of money I've spent on plants there's still a lot of open space for the weeds to colonize. I'm one overscheduled weekend away from losing control of the whole thing.

Solving this problem is going to be tricky because I'm on a flower diet. My current financial situation resembles the government's recent sequester. But at least I'm not fighting with myself about it. I have drafted and signed my Budget Control Act, and the automatic spending cuts have already gone into effect. No plant buying this spring.

This doesn't mean no acquisitions, however. Although on a diet I'm not good at self-denial. Besides outright theft, there are ways to get plants for free, and this is how I plan to populate my garden with more of the plants I like, so that fewer plants I don't like will move in.

Seeds- Luckily last year I saved some, so I have envelopes of nasturtium, poppy, and sweet pea seeds ready to go in the ground. And I bought some others before the sequester went into effect so I should have decent patches of nigella, more nasturtiums, and Sweet William soon, and climbing moonflowers on the porch.

Dividing- Some perennials can be divided every year and the chunks will grow to the size of the original within months. Hostas are the best example. A sharp shovel through the center of the clump before the plant leafs out (this is right now) soon results in a handsome reward. The same is true for summer blooming perennials like daylilies, sedum, bee balm, and yarrow, and anything that blooms in the fall. Spring plants like iris and primrose I'll wait to divide until after they're done flowering.

Other means- I said I drew the line at stealing but that's not entirely honest. In the past I've found some very good plants at abandoned and unkempt properties. My best columbine was dug up as a seedling from an unmowed graveyard. A bright yellow scotch broom was liberated from a railroad embankment. And the clumps of daffodils and snowdrops blooming in my garden- let's say they didn't come from the store.

I also plan to hit up my friends for extra plants they may have. In the past this is something I've done gingerly, since it can introduce hitchhiking weeds into your garden. So I'll be picky (sometimes beggars should still be choosers.) But I'm already thinking of which friends I'll generously offer to help thin their overcrowded gardens. I won't be cheating on my diet, and it will be phase one of my horticultural stimulus plan.

The shell had been cracked open to form a tiny cup, the top half severed cleanly from the bottom. It's hard to picture how a baby bird extricates itself like this, but every discarded eggshell is broken the same way.

Above the eggshell there was open sky; it didn't just get shoved out of the nest. When I went inside I did a little research, and found that many birds don't push empty eggshells out of the nest, but instead carry them far away from the nest location. And they don't drop both shell halves in the same place.

Biologists have done experiments showing that empty eggshells in the nest attract predators. In one study, whole eggs near empty eggshells were four times more likely to be found by predators than eggs with no broken shells nearby. It's not clear exactly why this is so, but a theory is that the bright white inside of an eggshell is like a beacon, allowing animals that prey on eggs and baby birds to spot a nest and its contents more easily.

Although flying off from a newborn chick to get rid of its shell is also fraught with danger (especially when it's still cold out) most birds seem to have a genetic aversion to keeping shells around once the eggs have hatched. In one study it was found that birds breeding for the first time removed empty eggshells from their nests, even before they laid their first egg.

A few days after coming across this unequivocal signal of changing seasons- on Easter, no less- I wished I had taken a photo. Rooting around the yard, I eventually found it, a little more crushed but still generally intact. Then it rained and the next day it was mush. Which must be why we're not walking on more eggshells this time of year.

The few flowers out are remarkable for their economy of form and their plucky opposition to the final charge of winter. Some manage by their thick skin, like the hellebores that have been in bloom all winter. Dinosaur-like, their coarse foliage stays above the muck, and the thick-petaled flowers carry themselves hunched over, heads down against the snow and pelting rain.

Snowdrops are ubiquitous right now, seeming to spring from the footprints of those who lived here before us. Here's a patch inexplicably in the middle of the woods, or a colony on the soft crumbly edge of a creek. The little white flowers spring out of neglected patches of ivy and pop up on the shady side of the house. I see them everywhere, almost always the common snowdrop, Galanthus nivalis, more rarely (but often enough that I always have to crouch down to check) one of the old fashioned double varieties. Like the hellebores and other winter flowers, they hug the ground. Their flowers hang down like pearl earrings from impossibly thin green threads and the petals are clamped shut on all but the most mild late winter days.

Other flowers can be tricked like trusting and unworldly children to blossom before their time. The screaming yellow branches of forsythia won't be demanding attention for another month, but a twig snapped off and put in a vase will bloom within days, and will stay in flower for weeks. The flowering quince is a shrub of few merits except for its beautiful, apple blossom like flowers that cover the branches before the leaves emerge. It blooms in the garden at the same time as the tulips and other showy bulbs, but branches stuck in water will flower a month early.

Until the first truly mild days, when the fat dandelion bursts into bloom and the sun feels warm, gardeners and anyone else sick of winter will have to rely on good eyesight, a lot of bending, and maybe even manipulation to make it over the hump.

It might be easiest to describe what it's like to be on the floor of the Philadelphia Flower Show the day before opening by explaining what it's not like.

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Once these related plants were separated by thousands of miles, they continued to evolve independently in response to their specific environments. So the maple became a small, draping tree with fine foliage in Japan, while its North American cousins are much taller and straighter. At the same time, pests and pathogens co-evolved with their host trees.

It was only in the early 18th century that these trees, segregated for hundreds of millions of years, began to reunite. Our own John Bartram was a pioneer of the reunification process, sending crates of American seeds to England, where plants like the Sugar Maple, the Tupelo, and the Red Oak had never been seen. He in turn received many foreign species in return. Asian plants had already made it to Europe on trade routes between England and the Far East, and Bartram gave them the final nudge to the New World.

Desegregating our planet's tree species has expanded the gardener's palette many fold, particularly when considering all the hybrids that have been developed from species native to different continents. We live in a world of endless choices regarding the size, color, habit, and type of bloom of our plants.

There's a collateral cost we pay in exchange for our panoply of choices; we're pretty much surrounded by exotic invasive plants. And now, we're beginning to see that there are some other serious downsides of our plants becoming world travelers. Many of our native trees are extremely threatened by exotic pests that co-evolved to bother but not destroy their foreign counterparts.

This has been happening for over a hundred years. It started with the Chestnut Blight, a fungus that co-evolved with the Japanese Chestnut, its natural host. While Japanese and Chinese Chestnut trees have decent resistance to the blight, our poor native chestnut was undefended and was efficiently exterminated from the American landscape.

A similar story can be told about our bygone native Elms, all laid down by Dutch Elm disease. More recent is the grave threat to American Ash species by the Emerald Ash borer, a beetle that hitchhiked from Asia, where it isn't fatal to their ash. Some biologists think that within ten years every ash tree in America could be gone.

It may be that the trees of our future will be those that have only one species, like the Gingko, the Franklinia, and the Sequoia. Because these trees have no living relatives, there is less likely to be a lurking pest or pathogen that has evolved to feed on them.

In the meantime, planting more than one specimen of any tree in your yard may not be the way to go. While the Ash borer is an immediate problem, there are other exotic pests on the horizon, hungry to prey on our unprotected native plants. Having a diversity of species- some native, some not- may be the best line of defense when the next tiny enemy army arrives.

For all the right reasons, natives have exploded in popularity over the last ten years. Seeking environmentally sustainable lifestyles gardeners have been rediscovering species that we've spent a century ignoring in favor of more exotic plants. Assuming they're used in the right location, many natives are excellent choices for low maintenance, panic-free gardens.

Last week, a reader asked about native plant recommendations for a small-scale Philadelphia garden she wants to renovate. It was a good winter exercise to make a list of native plants that would work in Yvonne's garden, which I'm imagining as mostly sunny, with a few shady corners. The list below includes six native perennials that range from 15 inches to 3 feet in height. As a collection, they will give color and interest in the garden from May to October (but particularly in the later half of the season) and these plants would look great massed all together, one placed about every 18 inches to two feet, shorter plants in the front. All the plants listed are easy to find, not expensive, and tend to either reseed or spread enough to be divided and shared every few years.

Sporobolus heterolepsis- As a flower person, I have had a hard time warming up to ornamental grasses, but this is my favorite because of its delicate texture. Like a fashion model next to a wind machine, the tufts move on the slightest breeze, tossing its foliage back and forth saucily. And like really good hair, it's impossible not to run your fingers through it. Great in a sunny, dry location.

Heuchera 'Autumn Bride'- For a semi-shady location, this is one of my favorite plants. The large, velvety foliage stays apple-green all season, and can be effective as a groundcover. In September white flower wands emerge above the leaves. 'Autumn Bride' is tougher than it looks, and it's reseeded itself in interesting places in my garden, including a rock wall where it looked great growing out of the cracks.

Ascelpias tuberosa- As long as you're a fan of bright orange, the long blooming flowers or Butterfly Weed are this plant's main attraction. Hundreds of small flowers appear in midsummer, set against dark green foliage. Planted in a sunny location, this handsome plant looks better every year, and is one of the preferred larval foods of the monarch butterfly- a caterpillar can almost always be found on the plant in late summer.

Aquilegia Canadensis- Our native columbine has its fifteen minutes of fame in late spring, when it sends up its complicated spurred red and yellow flowers. By mid-July it melts away until it returns the following year. Best in a little shade, columbine can be planted in and around other perennials, and will usually reseed itself into available nooks of the garden.

Eupatorium dubium 'Little Joe'- The species is massive, and it's not referred to as Joe Pye weed without reason; it's a little on the coarse side. But 'Little Joe' is a more dainty variety, with large leaves and big mauve flower heads that start blooming in August and don't stop until October. Besides providing structure, the most interesting feature of this plant is that it attracts pollinating insects like the porch light does at night. Butterflies love it.

Aster novae-angliae 'Purple Dome'- to finish out the season, this fall-blooming perennial blazes royal purple in October and November. It doesn't get mildew and the blossoms blanket the entire plant. On warm days in Indian summer the last bumblebees will be found clinging to the flowers, waiting for the autumn sun to dry the heavy dew off their wings before they can move again.

It took native plant expert Peggy Ann Montgomery to open my eyes to the possibility of exploiting brawny natives for their architectural presence. These robust plants are just what my vertically challenged garden needs, and here are three of her suggestions that I'm going to be using in my garden this year.

One of the few very tall woodland perennials is Actaea racemosa, formerly known as Cimicifuga before it recently underwent a name change. The five foot tall wands of white flowers seem to float above the fernlike foliage in midsummer. The foliage itself is attractive, and the overall appearance is delicate for a plant of this size. I'm going to put a couple of them behind the Annabelle hydrangeas in my shady front yard.

A plant I'm going to try sight unseen is Eryngium yuccifolium, the strangely named rattlesnake master. From photos and descriptions, this perennial looks like the horticultural equivalent of garden sculpture. The blue-green basal foliage resembles yucca, and stiff flower stalks grow to five feet. Many whitish-green thistle-like blossoms are held high, and the plant blooms from June to August, a long time for a perennial.

The fall-blooming perennial Vernonia can reach seven feet (the species) but there are more dainty varieties that top out at half that height, like the variety 'Iron Butterfly', which is still big enough to make a presence. Bright purple blossoms open in late summer, before the fall flush from asters and mums, but after most summer flowers are finished.

Oh, yeah. All these plants are tough, but particularly the Eryngium and the Vernonia. These two are happiest in dry soil, but will weather a hurricane. They don't care for compost, mulch, or rich soil, and have no other particular needs. The pollinators- bees, butterflies, other insects, and hummingbirds- love them.

Although I may have come at native plants more as a plant collector than an environmentalist, far be it from me to deny credit where it's due.

It took awhile, but our area did finally get cold enough for the ground to freeze hard. For now, there's not a lot to do outside. But it's the perfect season to sit on the couch (under a blanket, in a sweater) and fantasize about how this year, my garden is going to be more beautiful and more interesting than it ever has been before. I'm going to try to wean myself from the delicate, fragile, and fussy plants I tend to like, and to embrace the big, bold, muscle-y plants that I admire so much in other people's gardens.

Because what my garden is missing is the structure provided by architectural plants. I've been looking at a lot of pictures of European gardens, and I've been struck by the exuberance with which they embrace the oversized. Upon closer inspection, many of these steroidal plants are native to America, not Europe, and they look fantastic among the clipped boxwood parterres and raked gravel of English and French gardens.

On my side of the pond, I've been overlooking the plants that want to grow here, which in my narrow-mindedness somehow seem too common and coarse to be interesting, in favor of European roses and Mediterranean shrubs that need to be coaxed into tolerating the living conditions of my Philadelphia garden. So this year I'm determined to take a stab at native plants. I know- I'm at least ten years behind the curve on this. And I'm not altruistically considering the main reasons to use native plants; they're much more beneficial to wildlife and they use fewer resources. I just want my garden to look more English.

I asked native plant specialist and gardener extraordinaire Peggy Anne Montgomery, who works for American Beauties Native Plants, to share some of her favorite underused natives with me. In my next post, I'll give you the short list of the plants she suggests for a bold and beautiful garden, that will be testing my design chutzpah in just a few short months.