Spring Cleaning in the Garden

May 2014

Cleaning & Pruning

 As soon as I see the first flush of color in my garden, I spring into action with a small hand held rake that I use to carefully remove leaves from under each and every plant. It isn’t as hard as it sounds, and it gives me a chance to assess each plant for dead stems and branches, pruning as I go. Big oak leaves prevent water from penetrating the soil and provide cover for critters that might like a taste. I run all of my leaves through a shredder made for leaves, and use them to supplement mulch and as brown material in compost throughout the green seasons.

On my rounds, I pruned some shrubs – cutting behind spent blooms on hydrangeas and viburnums, clipped out dead, damaged or diseased branches, trimmed summer blooming shrubs to a desirable height (I never prune spring bloomers at this time or I forfeit almost all blooms). I sheared ornamental grasses to a height above the greening crown, well above ground level. I pulled dried flower stalks left behind for winter interest and food for birds. Sometimes I save spent Day lily fronds for craft projects (they make an inexpensive substitute for raffia).

I clean out containers of any dead annuals, making them ready for new plants and seeds. A soaking mixture of one part bleach to 10 parts warm water with a smidgen of dish soap will loosen soil and make clean up easier. Rinse thoroughly and allow to dry completely, preferably in the sun. Sanitation is the best pest control of all control measures.

Spring is the time to evaluate, trim and divide ornamental grasses. I leave the arching fronds and tan flowers for vertical interest in winter, although many could have been cut back in fall or winter. Officially, most garden sites recommend that you vary trimming for your grasses based on if it is a cool season or warm season grass. Generally, cool season ornamental grasses green up early in spring, almost as soon as temperatures exceed freezing, flowering early in summer. You might think warm season grasses died in the winter because it takes so long for them to send up new growth. Phalaris (ribbon grass), Stipa (feather grass), sea oats, tufted hair grass are all cool season grasses. Pampas, little and big bluestem, Miscanthus (maiden hair), Japanese blood grass, and fountain grass are warm season grasses.

If you wait too long to trim cool season grasses, you will have a hard time taking out the dried blades of last year without trimming the emerging leaves of this year – and they will be trimmed for the whole season. I leave about 1/3 of the plant, always cutting above the green, always above the point where the new leaves emerge from the stems or the plant can be irrevocably damaged. As hard as it is to believe, the new growth will quickly hide the bristling tan porcupines. I look like Edward Scissorhands out there – tossing great gobs of tan leaves left and right as I go, but I’ve seen people tie the leaves about half way up the stalk so they were able to carry off the trimmings in one bundle, but I think it’s harder to cut and I’ve never managed to keep the leaves in a bundle throughout the haircut.

I blow leaves and grass into a pile for shredding, paying careful attention to the rock sections where I have created dry creeks to manage water draining from the roof. As I do, I am reminded not to use rock in the garden needlessly – for example, as mulch. Rocks do not effectively prevent weeds and leaves cling stubbornly, showing up in stark color and textural contrast. They also create a microclimate in summer – similar to that of a hot oven.

Tree Care

Trees deserve a few thoughts in spring if we want to save them from ourselves and our best of intentions. Anything that stresses a tree brings weakens it and any injury to the trunk will allow infectious agents and pests to access to the interior where further damage is done, possibly decimating the tree. I have four hard and fast rules regarding trees. They are: 1) Do not top trees – ever. Trees must be allowed to reach their mature height and form and if that can’t be done, remove it and choose better for your landscape next time. 2) Mulch with two to four inches of mulch or leaf mold but not in contact with the trunk. Leave a clear ring around the tree that is about eight inches wide. Too much mulch smothers the roots and mulch in direct contact with the trunk softens the bark. 3) I like to keep plants out of the root zone because most of a tree’s roots are within the top 18 inches of the soil. I plant outside of the root zone, and as the tree extends beyond those plantings over time, any care that I provide to them is secondary to the needs of the tree. 4) Mechanical injury is another way in which we damage trees; those string trimmers should never touch the trunk of a tree.

Dividing

I never divide or share non-native and invasive plants. I check the lists of the Illinois Invasive Species Council before buying a new plant or dividing one in my yard. The United States Department of Agriculture (USDA) has detailed plant files and a page devoted to links to federal and state lists: https://plants.usda.gov/java/noxiousDriver. There are Federally listed non-native and invasive plants and it is illegal to share it, not that the plant police are going to show up at your home to take you away, but that they pose a real economic an biologic threat and I want to comply with the spirit of the law, removing them and discarding of them appropriately as I learn of their listing. The Federally listed noxious invasive plants include some well know plants, like water hyacinth, hydrilla, cattails, mimosa and many more.

Grasses need frequent dividing, every three to five years (five years for me) for renewal when the dead center becomes a notable hole. For all grasses and sedges, spring dividing is a safe bet. I never divide in summer when grasses are flowering, and I have all than I can manage in fall, when cool season grasses are safely divided, and so spring it is. At first, I was delighted for the multiplication, adding new clumps at almost no cost, but I was quickly sharing as I ran out of room for more stands and now, as often as not, I am composting the extra material, as reluctant as I am to let even an extra seed go unused.

I choose a cloudy day, preferably moist and cool to help prevent roots from drying. Digging grasses up can be challenging as their roots can be quite deep. I do my best to remove the root ball intact, I then make one slice to the center with a large finely serrated knife (devoted to gardening and never returned to the kitchen). With gloved fingers or forked hand cultivator or some combination of the two, I pry the ball apart, forcing it from a rounded ball into a row, with the center facing upward. I pull out as much dead material as possible and pull the row apart into as many plants as I have need for, usually into thirds or fourths. For very deeply rooted grasses, I like to use a drywall saw to plunge into the soil, sawing around the root ball and making as many divisions as I need. Pry plugs out and discard the dead center.

Many other perennials need to be divided occasionally, perhaps not as often as do grasses, but you will know when it’s time – the plant begins to perform rly when the soil in its sphere has been depleted and the roots are compacted, sometimes to the point that they are no longer capable of taking up even water. For this task, as a rule of thumb, I begin digging at the drip line, removing as much of the root ball as possible. I lay the plant out on the ground where I can drive my shovel into the center to divide the plant in half and in half again, quartering the plant. I then remove as much damaged or dead debris and plant it, pot it up for sharing, consign it to the compost heap or otherwise properly dispose of the remainder. As with any plant, I make a hole as deep as needed to keep the plant at the same height as it was originally, but not more, I spread out the roots as possible and I plant with native soil mixed with about equal parts compost.

Feeding

I feed my lawn and garden in spring. Different areas need different treatments. I choose between granular fertilizer, liquid fertilizer and compost applied to the outer root zone, the only place a plant is able to take up the nutrients. When I do use fertilizer, I always read the entire label and follow the directions without fail. Generally, mono-ammonium phosphate and ammonium polyphosphate, either alone or with some added potassium, make excellent starter fertilizers because of their high phosphorus to nitrogen ratios, high water solubility, and low free ammonia. As a general rule, unless a soil test indicates otherwise, I apply up to one pound of nitrogen per 1000 sq. ft., about ¼ what you would apply to grass. But, if I have it, I apply one inch of compost or leaf mold and eliminate additional fertilizer altogether. This is where having a good understanding of each plant’s needs while observing leaf color and growth habit will help you avoid excessive use of fertilizer.

I like Osmocote in containers and side-dress shrubs and perennials. Applying the Osmocote at the root zone and not right on top of the plant where it could burn the plant. Otherwise, I apply an inch of shredded leaves that have been decomposing in bags the winter, mixed with compost if I have it, favoring something with a little magic horse assisted potency, scattered around shrubs and perennials. In turf grass, I apply either a 10-10-10 granular fertilizer or scatter compost. I do not fertilize ornamental grasses as they can flop over if they have a flush of nitrogen induced growth. Later, I apply liquid fertilizer to containers filled with heavy feeders, as always, according to directions. If I did this to perennials or shrubs, they would produce week and floppy growth that might never harden off, so I rarely hit perennials with a second application.

Mulching

I add an inch of shredded leaves to all landscaped areas, around trees and under shrubs, but never within a few inches of the plant, or within four to six inches of the trunk of a tree. On top of that, I add a first cut shredded mulch or up to triple shredded mulch. Studies now indicate that the rougher shredded mulch performs better, much to my surprise. This top mulch also must not be in contact with the plant body. Mulch volcanoes are an abomination, almost guaranteed to kill a tree within three to five years, long enough for most homeowners to believe that the mulch could not be responsible for the decline.