SHRUBS, I’M SHARPENING MY SHEARS AND LOPPERS
Shrubs are Shrubby
A shrub is a shrubby, woody plant. (Now, that’s profound.) Numerous stems originating at or near ground level are what make a plant shrubby. Usually, no one stem ever gets the upper hand over other stems. For most shrubs, you need to get out there with your pruners to snip and lop every year.
How to prune a shrub depends on when it flowers and on what age stems provide the most ornamental effect. Does the shrub flower early in the spring, or later in the summer? Does it flower on old stems, on those that grew last year, or on new shoots?
Tree peony
And one more thing before we dive in: Here, I’m writing about pruning shrubs growing informally. Let’s shelve pruning hedges and, because they vary so much in their pruning needs, roses for another time.
Deciduous shrubs can be put into one of four categories according to the age of stems that flower or otherwise look their best. Here are some bare-bone guidelines for each of these categories. In my book, The Pruning Book, from which this is excerpted, I offer more detailed guidance with extensive lists of plants in each category (and, of course, details on pruning hedges, roses, and just about any other plant or pruning technique you can think of. Really.)
Old Looks Best
Deciduous shrubs whose old wood flowers or looks best. Included within this category are shrubs — witch hazel, rose-of-sharon, tee peony are examples — that naturally build up a permanent framework of branches. Rarely do they send up new suckers at or near ground level. These shrubs flower directly on older wood, or from shoots that grow from older wood.
Grouping plants always entails a certain degree of arbitrariness, and because of their disinclination to sucker, a few plants in this category could also be considered “trees,” especially if deliberately trained to one or a few trunks..
These shrubs are the easiest shrubs to prune: mostly, just don’t!
Some Annual Pruning Helps
Deciduous shrubs that flower best on one-year-old wood. Because they all flower only on wood that grew the previous season, annual pruning is needed to stimulate new growth, each year, for the following year’s flowers.
Renewal prune each year, removing the very oldest stems to make way for younger, floriferous stems to step in and replace older stems. Cutting a few stems low in the shrubs is also less work than shearing, and creates a more graceful, fountain-like growth habit, and keeps the plant low, neat, and abundantly flowering.
Prune those shrubs that flower early in the season right after their blossoms fade. But now, or just before growth begins, is the time to prune those shrubs that flower from summer onward. Pruning early-flowering shrubs right after they bloom allows you to enjoy their blossoms, but still leaves enough time for shoots to grow and ripen wood sufficiently for next season’s blooms.
The one-year-old shoots on which flowers are borne may grow mainly from older stems up in the shrub, or else mostly from ground level. The location of these flowering shoots determines pruning technique, so I have subdivided this category into two groups, grouped plants accordingly, and follow with instructions for each.
Shrubs such as lilac, forsythia, and mock orange flower best on one-year-old wood originating from older wood up in the plant.
Peer in at the base of the mature plant and you’ll notice wood of various ages growing up from ground level. Begin pruning by cutting away near ground level, some of the very oldest stems. Those oldest stems are also the tallest ones, so these first cuts quickly lower the plant.
Each year also remove at ground level a portion of the youngest stems so they don’t crowd with age.
Abelia and kerria are among those shrubs that flower best on one-year-old wood originating at ground level; they need more drastic pruning. Every year cut away all wood more than one-year-old, either right to ground level or else to a vigorous branch originating low on the plant. You can tell the age of a stem by its thickness and, with many plants, by the color or texture of the bark. 
Blossoms on New, Growing Stems
Deciduous shrubs whose current growth flowers or looks best: Here we have shrubs valued only for their new growth. And yes, in some cases we value the plant for the young stems themselves.
Red-osier dogwood stems in winter
This group of shrubs, which includes red-osier dogwood (whose young, red stems “ignite” with winter cold), butterfly bush, New Jersey tea, and Hills-of-Snow hydrangea, is very easy to prune: simply lop the whole plant down to the ground just as buds are swelling. 
Time for Renovation?
You perhaps have inherited, with your property, a neglected, old shrub offering you a tangled mass of stems, an awkward posture, and few flowers. Can this shrub be brought back to its former glory? Probably.
You have two options in renovating this shrub. The first is the drastic one: you merely lop the whole plant to within one foot of the ground just before growth begins for the season. The plant won’t be pretty for a few years but after that you’re on your way to a “new,” shrub, full of blossoms and with a graceful growth habit, a whole new plant from the ground up.
A second option is gradual renovation, removing a couple of the oldest stems each year over a period of four or five years. Although this takes more time, the plant will look decent throughout the recovery period.
Rather than renovation, you might instead consider capitalizing on your overgrown shrub’s age and venerability by transforming the plant into a picturesque small tree. Not all shrubs make this transition gracefully; devil’s walkingstick, hawthorn, and hazelnut are among those that do.
Select as trunks two or three of the oldest stems having pleasant form and growing from ground level to as high as the proposed crown of your tree-to-be. Remove all other growth from ground level to the proposed crown.
Even easier is to let the deer prune for you, in which case the bottom of the crown will be as high as the deer care to reach.
Deer pruned yew
BREWING UP BATCH OF POTTING SOIL
Prime Ingredients for Any Potting Mix
Many years, my gardening season begins on my garage floor. That’s where I mix the potting soil that will nourish seedlings for the upcoming season’s garden and replace worn out soil around the roots of houseplants. Why do I make potting soil? Why does one bake bread?
There is no magic to making potting soil. When I first began gardening, I combed through book after book for direction, and ended up with a mind-boggling number of recipes. The air cleared when I realized what was needed in a potting soil, and what ingredients could fulfill these needs. A good potting soil needs to be able to hold plants up, to drain well but also be able to hold water, and to be able to feed plants. The key ingredients in my potting mix are: garden soil for fertility and bulk; perlite for drainage; and a mix of peat moss and compost for water retention.
Why not just dig up some good garden soil? Because a flower pot or whatever container a plant is growing in unavoidably creates “perched water table” at its bottom. Garden soil, even good garden soil, is so dense that it will wick too much water up from that perched water table. Waterlogging is apt to result, and waterlogged soil lacks air, which roots need in order to function. (More about perched water tables and lots of other stuff about soil, propagation, plant stresses, and more can be found in my book The Ever Curious Gardener: Using a Little Natural Science for a Much Better Garden.)
Coarse mineral aggregates — perlite, in my mix — make potting soils less dense, so water percolates more readily into the mix, through it, and out the bottom of the container. Other aggregates include vermiculite, sand, and calcined montmorillonite clay (aka kitty litter). I chose perlite because vermiculite breaks down with time and can contain asbestos. Sand is heavy, although this can be an effective counterbalance for top heavy cactii.
The peat moss and compost in my mix are organic materials that slurp up water like a sponge; plants can draw on this “water bank” between waterings. One peat to avoid is “peat humus,” a peat that is so decomposed that it has little water-holding capacity. Organic materials also buffers soil against drastic pH changes and cling to nutrients which are slowly re-released to plant roots. Otherwise these nutrients run out through the bottom of seedling flats and flower pots.
Peat is relatively devoid of nutrients but the compost provides a rich smorgasbord of nutrients. And I can brew it myself. Just letting piles of autumn leaves decompose for a couple of years produces “leaf mold,” which has roughly the same properties as compost.
Potting soils made with garden soil and compost might need to be pasteurized to eliminate pests especially weeds. Too much heat should be avoided, however, because toxins which injure plants will form and beneficial organisms will be eliminated. When I am going to pasteurize, I do so only to the garden soil in the mix; my composts get to above 150°F all on their own.
To pasteurize potting soil, put it in a baking pan, bury a potato in it, and bake it in a medium oven. When the potato is baked, the soil is ready. Pasteurization is not absolutely necessary; I pasteurize to kill weed seeds.
What You Buy Isn’t . . .
Go out and buy a potting mix and, in all likelihood, that mix will be devoid of any real garden soil. You can mix up a so-called “soil-less” potting mix by sieving together equal volumes of peat moss and perlite. Since the mix has no garden soil or compost to supply nutrients, add 1/2 cup of dolomitic limestone, 2 tablespoons of bone meal, and 1/2 cup of soybean meal to each bushel of final mix. This mix has enough fertility for about a month and a half of growth without additional fertilizer.
I favor traditional potting mixes, which contain real garden soil. Real soil adds a certain amount of bulk to the mix, as well as a slew of nutrients and microorganisms. Real soil provides buffering capacity, which allows for some wiggle room in soil acidity.
The Magic Happens
I wrote early on, “There is no magic to making potting soil.” I could toy with ratios and make a potting mix from perlite plus compost, perlite plus compost plus garden soil, even straight compost, depending on the texture of the compost.
Going forward, I’m going to experiment with coir and/or PitMoss, both possible substitutes for peat moss, the harvest of which is environmentally questionable.
For my first batch of potting mix for this season, I’ll stick with my usual recipe. Step one is to give the garage floor a clean sweep. 
Then I pile up on the floor two gallons each of garden soil, peat moss, perlite, and compost. On top of the mound I sprinkle a cup of lime (except if I’ve sprinkled limestone on the compost piles as I build them), a half cup soybean, perhaps some kelp flakes.
This is a mixed bag of ingredients, but I reason that plants, just as humans, benefit from a varied diet. I slide my garden shovel underneath the pile and turn it over, working around the perimeter, until the whole mass is thoroughly mixed. 
I moisten it slightly if it seems dry. When all mixed, the potting soil gets rubbed through a 1/2″ sieve, 1/4” if it’s going to be home for seedlings.
I end by clicking click my heels together three times and reciting a few incantations to complete this brew that has worked its magic on my seedlings, houseplants, and potted fruits each season.
TO PRUNE OR NOT TO PRUNE, THAT IS THE QUESTION
A Sharp Knife is not Enough
“Prune when the knife is sharp” goes the old saying. Wrong! (But don’t ever prune if the knife—or shears—is not sharp.) There are best times for pruning, and they depend more on the type of plant and the mode of training than on the sharpness of the knife.
Cat is ready to prune
As each growing season draws to a close in temperate climates, trees, shrubs, and vines lay away a certain amount of food in their above- and below-ground parts. This food keeps the plants alive through winter, when they can’t use sunlight to make food because of lack of leaves (on deciduous plants) or cold temperatures. This stored food also fuels the growth of the following season’s new shoots and leaves, which, as they mature, start manufacturing their own food and pumping the excess back into the plant for use in the coming winter.
A similar situation exists in some tropical and subtropical climates having alternating wet and dry, or cool and warm, seasons. Plants must wait out those quiet times drawing on their reserves.
Old apple tree, unpruned & pruned.jpg
When you prune a dormant plant, you remove buds that would have grown into shoots or flowers. Because pruning reapportions a plant’s food reserves amongst fewer buds, the fewer remaining shoots that grow each get more “to eat” than they otherwise would have and thus grow with increased vigor.
(For more details on above and what follows, see my book, The Pruning Book, available from the usual sources or directly from me, signed, at www.leereich.com.)
Summer or Winter, Growing or Dormant?
As the growing season progresses, response to pruning changes, because shoots of woody plants cease to draw on reserves and stems stop growing longer well before leaves fall in autumn. In fact, growth commonly screeches to a halt by midsummer. So the later in the growing season that you prune, the less inclined a woody plant is to regrow — the year of pruning, at least.
Traditional theory holds that summer pruning is more dwarfing than dormant pruning, but contemporary research puts this theory on shaky footing. True, if you shorten a stem while it is dormant — in February, for example — buds that remain will begin to grow into shoots by March and April, while if you cut back a shoot in midsummer, the plant might just sit tight, unresponsive. Ah, but what about the following spring? That’s when the summer-pruned shoot, according to this recent research, waits to respond. (Plants have an amazing capacity to act however they please no matter what we do to them.)
What are the practical implications of all this? First of all, if you want to coax buds along a stem to telescope out into shoots, prune that stem when it’s dormant.
Pollarded catalpa
On the other hand, summer is the time to remove a stem to let light in among the branches (to color up ripening apples or peaches, for example), or to remove a stem that is vigorous and in the wrong place. Watersprouts, which are vigorous, vertical shoots, are less likely to regrow if snapped off before they become woody at their bases.
Under certain conditions, summer pruning can be more dwarfing than dormant pruning, because regrowth following summer pruning can be pruned again. And again. Under certain conditions, summer pruning can also prompt the formation of flower buds rather than new shoots — just what you want for solidly clothing the limbs of a pear espalier with fruits or the branches of a wisteria vine with flowers.
Pear, before and after summer pruning detail
Red currant espalier before & after summer pruning
Unfortunately, the response to summer pruning depends on the condition of the plant as well as the weather. A weak plant may be killed by summer pruning. A late summer wet spell, especially if it follows weeks of dry weather, might awaken buds that without pruning would have stayed dormant until the following spring. Also factor just how much growth you lop off a stem as well as temperatures in the days or weeks following pruning.
Whose Health?
Regrowth and flowering are the dramatic responses to pruning; you also must consider plant health when deciding when to prune. Although immediate regrowth rarely occurs after late summer or autumn pruning, cells right at the cut are stirred into activity to close off the wound. Active cells are liable to be injured by cold weather, which is a reason to avoid pruning in late summer or autumn except in climates with mild winters or with plants that are very hardy to cold.
Dormant pruning just before growth begins leaves a wound exposed for the minimum amount of time before healing begins. Some plants — peach and its relatives, for example — are so susceptible to infections at wounds that they are best pruned while in blossom. On the other hand, the correct time to prune a diseased or damaged branch is whenever you notice it.
Also consider your own health (your equanimity and your energy) when timing your pruning. Depending on the number of plants you have to prune, as well as other commitments, you may not be able to prune all your plants at each one’s optimum moment. I prune my gooseberries in autumn (they never suffer winter damage), my apples just after the most bitter winter cold has reliably move on, and my plums (a peach relative) while they are blossoming.
Sap oozes profusely from cut surfaces of maples, birches, grapes, and kiwis if they are pruned just as their buds are plumping up in spring. The way to avoid this loss of sap is to prune either in winter, when the plants are fully dormant, or in spring, after growth is underway. The sap loss actually does no harm to the plants, so rushing or delaying pruning on this account is not for your plant’s health, but so that you can rest easy.
