Back Issue
July/August 1995

The Organic Perennial Garden
by Nancy DuBrule

The term "organic gardening" conjures up an image of rows of raised beds bursting with oversized, delicious vegetables. The desire to grow food organically, without the use of toxic chemicals, is easy to understand—why would anyone purposely add poison to their own food? But when I mention organic perennial gardening, many people simply ask "Why does it matter, you aren't going to eat these plants." To this I reply:
1. You just might want to eat the flowers. Edible flowers are the latest rage and there are quite a few excellent books published on the subject.
2. As your design skills develop, you may decide to incorporate herbs and vegetables into your perennial borders.
3. It is very possible that someday you (or the next owner of your house) may convert your flower garden into a vegetable garden, and it is unwise to leave a legacy of toxic residues.
4. Poisons applied to any type of garden or lawn may contaminate well water and leach into the ground water.
5. Chemical fertilizers burn up organic material and kill soil microorganisms.
6. The most compelling reason to grow an organic perennial garden is that these methods work! The gardens that I tend are lush, oversized, abundant, and healthy. People always comment "What are you feeding these plants?"

Preparing the new perennial bed
The guiding principle in organic gardening is that the gardener feeds the soil, not the plants. Rich, healthy soil, alive and teeming with soil microorganisms, is the key to a healthy garden.

A soil that is fed organically is teeming with life and can sustain plant growth for a long time if left alone. Chemical fertilizers are not used. Chemical fertilizers are water soluble and leach out of the soil with every rain or watering. Therefore, you must continuously add them, week after week, to keep the plants growing. Your plants become "hooked" on chemicals and if you stop fertilizing, the plants decline quickly, as the soil has become "dead" and has no inherent source of natural fertility.

To properly prepare your soil, start with a soil test. A soil test will specify the pH of the soil and identify deficient nutrients. Improve your soil by adding limestone, compost, rock phosphate and greensand.

Soil Test: Aim for a pH of 6.5-7.0 in your perennial bed; if your pH is low, the specific amount of lime you should add to raise the pH will be listed in the soil test results. Use calcitic lime (calcium carbonate) unless your soil needs extra magnesium and calcium, then you may want to use dolomite limestone (calcium-magnesium carbonate). A rule of thumb for slightly acidic soils is to apply 5 lbs. of lime per 100 square feet to raise pH by one point. In general, clay soils will need more lime than sandy soils to change pH.

Compost: Initial soil preparation includes the addition of large amounts of compost. If you do not have your own compost pile, you can buy it at a garden center. Connecticut has at least four large commercial composting operations and bagged compost is generally sold as "composted manure." If you need a lot of compost, start by calling your town's public works department. Many Connecticut towns operate composting facilities and offer free compost to town residents.

I generally use compost as a substitute for peat moss because peat moss is inert and contains no soil life. It is acidic (and our Connecticut soils usually are already too acidic as it is). It is also hard to wet, absorbing many times its weight in water if allowed to dry out. I use peat moss when planting acid loving (ericaceous) plants such as rhododendrons and azaleas.

The reason that compost is so important is that the billions of soil microorganisms that live in compost break down organic matter and release it to the plants slowly. This is how the soil feeds the plants. When you feed the soil by adding compost, organic mulch, rock phosphate, greensand, bone meal, blood meal, and other mixed, blended organic fertilizers, you are actually feeding these microorganisms. This is the same process that takes place in nature. No one feeds the plants in the woods and meadows, yet they grow with great vigor. Organic material is deposited on the ground in the form of fallen leaves, matted down meadow grasses, etc. These create a layer of organic matter that is decomposed slowly, releasing nutrients back to the plants.

Rock phosphate: This is a mineral source of phosphorus and breaks down very slowly in the soil. It contains phosphorus as well as calcium and 18 other essential trace minerals. I always add this deep into the soil when preparing a garden bed. It does not move rapidly in the soil so it is useful to dig it in deeply when you have the chance. The phosphorus is released very slowly, over many years. It really helps plants to have bigger, more abundant flowers and stronger stems. Consult the phosphorus level listed in your soil test (L, M, H) and add the needed amount of rock phosphate according to the amounts listed on the bag.

Greensand: This is a naturally occurring iron-potassium silicate. It also takes a long time to break down. It has the consistency of sand but is a dark green color. Besides being a long lasting mineral source of potassium, it also contains iron, magnesium, calcium small amounts of phosphorus, and up to 30 other trace minerals. It loosens clay soils and helps in the release of nutrients that are bound up in the soil structure. It works miracles! Potassium helps plants develop a strong, deep root system as well, which may account for the tremendous vigor of the plants growing in soil amended with greensand.

Spring care
In the spring, I side-dress the plants with compost and a mixed blended organic fertilizer (usually a 5-3-4). To side-dress means to apply alongside the plants. Scratch the fertilizer into the soil surface. In late May, once the soil has warmed up and the self-sown seedlings of perennials and annuals have made their appearance (I'm a cottage gardener and I welcome them), I mulch the garden with shredded bark, buckwheat hulls, cocoa bean hulls, or other organic material. At that point, my gardens are all set and the bulk of the work is done!

Summer care
In the summer, I do supplemental feeding only to those plants that are heavy feeders or that I expect to rebloom or continuously bloom. I scratch in a second round of compost and organic mixed blended fertilizer (this time, usually a 2-3-3, higher in phosphorus, the middle number, to promote late summer and fall blooming) in mid-July to roses, buddleias, delphiniums, annuals, and rebloomers such as veronicas, perennial salvias, nepetas, coreopsis, centranthus, etc. The rest of the plants, as long as they look healthy and lush, as they usually do, are left alone.

The only other supplemental feeding that I do is liquid feeding of plants that are stressed by the high heat and humidity of the summer. For example, I usually foliar feed roses in late July and August with liquid seaweed, also known as kelp, every two weeks. This helps them to withstand the summer conditions. You've probably noticed that roses do best in May, June, September and October and languish in the hot months. This is perfectly natural.

Foliar feeding is applying a dilute fertilizer solution to the leaves. This gives you fast results because the nutrients are absorbed directly into the plant through the foliage and do not have to be translocated from the soil and up the stems and out to the leaves. Liquid seaweed is an amazing fertilizer source. It provides plants with trace elements and natural growth hormones, improving their general health and vigor and increasing their resistance to insects and diseases.

I also water the garden with fish emulsion once or twice in the peak of summer. Some years, if I am really busy, I am only able to spot feed the plants that seem to need it the most. Other years, especially if the summer is quite brutal, with high heat, drought, or extremely long periods of high humidity, I try to liquid feed the entire garden. I use a proportioner, a device which attaches to the faucet and sucks up a dilute solution of fish emulsion or liquid seaweed into the hose. This makes it a quick and easy process, giving the stressed out plants a "pick-me-up" and providing them with valuable trace nutrients.

After a few years of this kind of care, my gardens maintain a high level of fertility. When you plunge your hand beneath the mulch into the soil in my perennial beds, you will find a soil that is rich, dark, teaming with microorganisms and earthworms. Nothing makes me happier than to witness the transformation of a poor, lifeless soil into one so fertile and rich. An organic gardener knows that a healthy soil is the only way to assure a healthy garden!

Nancy DuBrule is the owner of Natureworks, an organic garden center specializing in perennials in Northford. She is is the current president of NOFA/CT, and the co-author, with Marny Smith of Rowayton, of the book A Country Garden for your Backyard published by Rodale Press (1993).

Resources
The Northeast Organic Farming Association of Connecticut (NOFA/CT) is an independent, non-profit organization dedicated to strengthening the practice of ecologically sound farming, gardening and yard care, and to helping consumers have increased access to safe, healthy food. For more information, contact
NOFA/CT
PO Box 386
Northford, CT 06472
203-484-2445

Connecticut Gardener
P.O. Box 248
Greens Farms, CT 06436
1-800-600-0476
email: editor@ conngardener.com