Gardening Success: Fall for It By Paula Steers Brown, Contributing Columnist
mounded beds on each side of a garden path at Lewis Ginter Botanical Garden
greatly improve drainage and visually divide the garden.
The August heat may have curtailed activity in the
garden except for watering and mowing, but it is not too early to start
thinking about fall gardening. In fact, in the South, brutal summers and
drought conditions might force us to revise our gardening calendar to make
better use of autumn. Maintenance and cleanup tasks remain important, but
more emphasis should be put on planting and soil preparation, jobs many
people perform only in springtime.
Summers here are much harder on plants than the usually
mild winters, so young perennial plants and shrubs actually have a better
chance of surviving if planted in the fall. Root systems will not grow in
extreme heat, but do well in the cool of autumn and still grow throughout
the winter, so even though what you see above ground is brown and dormant,
your fall-planted specimens will use this time to get well-established.
outlined with stone improve drainage and establish pleasing pathways in this
late summer garden at Andrew Jackson’s home, The Hermitage, in Nashville,
Bed preparation is the key to success in gardening.
People often want to bypass this unglamorous step that involves time,
expense, and hard work so they can jump ahead to the fun part of buying
pretty plants. Avoid this short-sighted mistake, whether establishing new
beds or improving an existing landscape. Amending the soil, removing weeds,
and assuring proper drainage are essential first steps. Chemical fertilizers
and pesticides merely mask soil problems that would not exist if people
would take the time and effort on the front end to prepare the soil with
healthy organic matter, as most composts can reduce soil-borne diseases.
August is a great time to start bed preparation.
First, evaluate your existing soil. Is it heavy clay or light, sandy soil,
or a combination? You can have it tested through your county’s cooperative
extension agency — which can make recommendations, or you can perform your
own informal “squeeze test.” If the soil crumbles immediately or runs
through your fingers, it is sandy; if it holds together firmly, it is clay.
Sandy soil drains well, warms up early in the spring, and is easily
penetrated by roots so that the plant can get oxygen, bacteria, and other
helpful microorganisms. Its chief defect is its inability to hold water,
which also means nutrients leach out with the moisture. Clay soil holds
water and nutrients very well, but if plants become waterlogged due to lack
of drainage, roots cannot get oxygen. If you are part of the overwhelming
majority with less than perfect soil — not to worry — it can be remedied
by adding organic material in suffcient amounts worked in to the proper
depth, as outlined below.
Use Those Leaves Consider making use of your
leaves rather than sending them to the landfill. Carbon-rich brown leaves
can be composted as a ready source of organic enrichment for your soil,
whether shredded with a mulching mower or gathered for composting. Pile
composting is the simplest and cheapest way to go, where leaves and yard
wastes are stacked in an out-of-the-way corner. It takes six months to two
years for the leaves to decompose, but the resulting “black gold” leaf
mold excites the wise gardener who has any interest in lush plants and
saving money on soil amendments. Compost bins (available commercially or
built by the handy gardener with chicken wire over a simple wood frame) can
be tucked away into even the smallest city gardens as they are in every
self-respecting garden in England.
From my son’s 7th-grade
Virginia Junior Academy of Science project on composting, a workable formula
emerged. Fill compost bins halfway and allow to sit over the winter. Bag the
rest of your leaves and add them to the bins throughout the following year,
alternating layers with nitrogen-rich grass clippings gathered each time you
mow the lawn. This brown/green layering provides the quickest “heating
up” of the compost pile. Keep it moist and accelerate the process further
with manure from a horse farm or even from the neighbor’s pet rabbit. My
children also understood science lessons on potassium better when they
remembered their banana peels eventually promote tons of flowers.
Before starting to amend your soil, it is important to kill all the weeds.
Organic purists suggest a process called solarization, where the outlined
area for the new bed is covered with four sheets of wet newspaper or one
layer of lightblocking black plastic, then weighted down with mulch. This
chemical-free approach destroys all weeds, but takes about six months. If
your time frame is short or if you have stubborn wire grass or Bermuda grass
to remove, you will need to use a systemic, non-residual herbicide such as
Roundup. Outline the bed with a garden hose and apply Roundup on a non-windy
day. Wait two weeks, then rototill through the vegetation that has died. If
weeds are still present, repeat the application until all have been killed.
Do not rush this process or you will be fighting weeds for the rest of your
amendments. Addressing drainage from the outset alleviates many
problems. Losing plants over the winter is more often attributable to winter
wetness than to cold-hardiness. To test for drainage or “percolation,”
dig a hole 12 inches in diameter and about as deep, fill with water, let
drain, and fill again. If the second round of water has not drained in one
hour, drainage to this area needs improvement. Amending the soil with
sufficient amounts of organic material will produce better drainage not only
by improving soil structure, but also by literally raising the level of the
soil to create a slightly mounded bed.
Bags of compost or leaf humus (check the label: 40
percent organic provides the best nutrients) should be mixed with sphagnum
peat moss (the kind that comes in bales). Peat moss improves aeration of
clay soils to promote drainage and improves sandy soils’ ability to hold
water and nutrients. Compost alone can compact too much, and peat moss has
the added advantage of taking years to break down. A good rule of thumb is
to add one-third organic matter by volume, or 4 inches to every foot of
soil. Blend 2 inches of compost with 2 inches of peat moss, till into the
existing soil to the depth of the tiller, and you will have 12 inches of
prepared bed that is about one-third organic and mounded slightly above
ground level, further improving drainage. To brace the edges of this
slightly raised bed after tilling, outline with stone, brick, or other
appropriate material, at least until the roots get established, which then
hold the soil in place. Stacked rock walls are very popular now, are
aesthetically beautiful, and assure good drainage by raising the soil level
even higher. Bermed beds provide good drainage and work well if you need to
screen views or visually separate parts of the garden.
Harvest herbs at
summer’s end such as these at Lewis Ginter’s Children’s Garden, but
leave some seed heads of flowers for the birds to enjoy.
Plants root much better when this organic matter is worked deeply into the
soil. Deep tilling improves drought tolerance and resistance to fluctuating
temperatures. Revered authority on English cottage gardening, Gertrude
Jekyll, swore by a process called “double digging” whereby the topsoil
is completely removed to a spade’s depth of 12 inches and set aside so
that the next 12 inches down can be amended and then tilled (which means
tilling extends 24 inches below ground level!). My ex-husband used to
contend that by attempting this ideal, I wanted the holes for my roses dug
to Elmer Fudd’s specifications: “Clean through to Chinee.” I now
recommend a more practical tilling depth of 8-9 inches with just a
rototiller — easier on the back, the marriage, and there’s less
settlement all the way around.
Cut or Not to Cut... Certain plants such as herbs are
at their peak now and should be harvested, bundled, and stored to be used in
dried form. Pot up some herbs to take inside for winter use. “Silver
King” artemisia is its most beautiful at the end of August and should be
cut for use in dried arrangements along with celosia, money plant, and
“Coronation Gold” yarrow. Fall is the time to prune wisteria and
climbing roses. Grasses, however, should not be cut, but left for their
subtle beauty and movement to be appreciated in the winter garden. Seed
heads of sedum also enhance the winter landscape and should be left after
the foliage has died. Song birds are attracted to the seeds of coneflower,
black-eyed Susan, monarda, liatris, ligularia, eupatorium, echinops,
helianthus, and hosta so leaving some of them might provide food for the
birds and music for you. Clip hedges for the last time of the year, making
sure growth at the base is wider than at the top so sunlight gets to the
bottom, keeping growth there full.
Unless testing has shown your soil to be high in phosphorus, it is a good
idea to add a superphosphate fertilizer, especially key in fall-planted
perennial gardens, to promote good root establishment and flowering. For
every 100 square feet of bed, use 2 pounds superphosphate (0-20-0), 2 pounds
of 5-10-5 fertilizer, or 11⁄4 pounds of 8-32-16 wheat starter
fertilizer. Be sure to till this in, as phosphorus is immobile in the soil.
When planting individual trees or shrubs, holes are dug a few inches wider
than the rootball, but not deeper because the soil will settle somewhat and
drainage problems might arise if the plant sinks. Allow prepared beds to
settle a bit before planting, and do not worry if a major tailgate party
bumps your weekend planting time back a week or two. Sandy McDougle,
perennial plant guru and owner of Sandy’s Plants, Inc., in Mechanicsville,
was the first person to impress upon me just how far the window of
opportunity can be opened for fall planting of perennials. For many years,
Sandy was a schoolteacher with a passion for gardening. However, with the
school year starting in September, there was no time for fall planting until
Thanksgiving break. Each year her dream plans had to wait until late
November to be executed, and each spring through summer she was rewarded
with the huge success of her late fall efforts! One of Sandy’s top
recommended perennials for planting this fall is Salvia
greggii for its continuous bloom, drought tolerance, and overall low
Of course, fall is also planting time for spring bulbs.
For extended color, plant some daffodil bulbs behind peonies or later
emerging plants such as hostas so that the spreading foliage will cover the
daffodils’ yellowing leaves for a nice companion planting.
can be left on the shrub to provide winter interest, but do cut some for
inside arrangements. Cut in September when petals start to feel slightly
dry. Do not cut stems past the green part to assure you will have blooms
next year in case your variety blooms on last year’s wood. Provide good
air circulation while drying.
transplanting. One sign that a plant needs dividing is the “donut
effect” observed when a dead space becomes apparent in the center of an
original plant that has lost its vigor and newer offshoots encircle it. You
may also notice a large plant lush with foliage, but not blooming as much as
it did in seasons past. Dividing can really rejuvenate such plants. Certain
perennials, such as peonies, can only be divided or moved in the fall. When
moving them, get a good bit of dirt in the rootball and place the “eyes”
at ground level. Poppies, dianthus, and Siberian iris are best divided in
the fall. Some resilient plants like daylilies and hosta can even survive
summer transplanting, but respond well when moved in the fall. Perennials
transplanted now should be cut back to half or one-third their height,
making them more manageable and less droopy until they adjust to their new
location. Transplant perennials after flowering, preferably on a cloudy day,
and provide some shade for a couple of days. The process is most successful
if plants can rest a month before freezing temperatures are expected.
chores. A lot of the season will be devoted to getting up leaves and
cutting brown stalks. As far as pruning perennials, generally the rule is
“if it’s brown, cut it down,” but if you want to learn specifics about
the maintenance and pruning of perennials, I highly recommend The
Well-Tended Perennial Garden by Tracy DiSabato-Aust as the best, most
complete care manual I have seen.
Fall is the best time to sow an entire lawn or repair a
bare patch, but rake it well first to remove any thatch and spike to aerate.
Lawns benefit too from an annual organic top dressing of a leaf mold/peat
mixture just after aerating. Now is the time to collect seeds from
perennials before you cut them back, let them dry thoroughly, and store for
spring planting. Also, do any fall mulching you intend to do before you cut
perennials to the ground, as mulch can damage some of the crowns of plants
such as coreopsis “Moonbeam” and Japanese blood grass. The only crowns
that need protecting in winter are those of tender plants such as cannas.
Mulching is generally overdone, so go easy. Ideally, as you cultivate your
thankful plants in their healthy soil in the cool fall weather, they will
grow so fat from your good tending that they muscle out the mulch entirely.
Luxuriance will be the payoff for your hard work.