Thursday, May 26, 2016

Organic Garden Management - Part 1

By Lindsay Del Carlo, Trial Garden Manager
Many of our newer gardening customers want to garden organically, so I've asked our Trial Garden manager Lindsay Del Carlo to write the next few blog posts to share our own organic gardening techniques. Here is the first post focusing on soil preparation and care. – Renee

Our trial garden has been managed organically for over 25 years by observing organic cultural practices that produce a thriving, healthy garden:
  1. Good soil preparation is basic and vital to growing a healthy organic garden and using cover crops, organic fertilizers and compost helps to improve soil structure and fertility and increase both overall plant health and resistance to pests and diseases.
  2. Crop rotation helps to decrease the need for excessive fertilizer and prevent build-up of soil disease. No garden is completely pest free, and there are now many useful new organic pest control products on the market for effective pest control.
  3. Having a variety of plants that attract beneficial insects helps to control pests by creating a working, self-sufficient ecosystem. 
My posts will explain these classic organic techniques one by one:

It All Starts With Building Healthy Soil – Using Compost to Build Great Soil
Finished aged compost
to add to garden beds
Throughout the gardening seasons, every time we start or transplant a new crop into one of our raised garden beds, we first prepare the soil by adding a few inches of aged compost and turning it into the top 8 inches of the soil with a fork. Compost is an excellent soil conditioner, improving the soil structure and adding micronutrients that feed plants.

In our extremely sandy soil, the compost acts like a sponge that holds onto water and helps keep soil from drying out so quickly. In a garden with denser clay soil, adding compost aides in keeping soil loose and non-compacting so it will drain better.

Compost also provides plant roots with more air space which is actually vital to plants. Whether you make it or buy it, be sure your compost well aged, and completely broken down for the best availability of nutrients. Renee's Garden offers a good Compost Guide if you want to learn how to make your own low-cost, nutrient-rich compost. 

Fertilizing Regularly Is An Important Part of Organic Practice
Organic Fertilizers L to R:
Liquid Kelp, Sustane grainular,
Earth Worm Castings,
Fish Emulsion
In addition to preparing our soil with compost, we also consistently use good organic soil amendments and fertilizers. Earthworm castings are the end product from worms digesting organic materials, and it is odorless and non-toxic. A little goes a long way with earthworm castings and they contain abundant essential elements plants need for healthy growth and can really make a marked difference in your garden.

Organic fertilizers provide vital nutrients and help plants to build strong tissue, making them more pest resistant. Synthetic fertilizers, although they work very quickly to promote quick growth, encourage fast development of very soft plant tissue that becomes a magnet to pests like aphids and mites which can easily penetrate the plant tissue to feed on it. Knowing the fertilizer requirements for different crops is important to avoid over or under-fertilizing and so that the crops can be rotated properly.

We use a granular, certified organic fertilizer called Sustane. (Fertilizer brands are regional, so inquire at a good independent garden center for what is available in your area or look online). This granular fertilizer breaks down slowly in the soil to feed plants over a long period of time. Organic fertilizer in liquid form is faster acting than granular fertilizer. For heavy feeding crops (see your packet back), we also supplement the slow release granular fertilizer with a liquid kelp/ fish emulsion mixture (1 tablespoon each liquid fish emulsion and liquid kelp per gallon of water) as either a foliar spray or soil drench to give plants of any age a quick boost.

Crop Rotation Controls Disease and Maximizes Nutrients 
Crop Rotation is a very important practice which helps to avoid depleting the soil of nutrients and a build up of soil pathogens. Some vegetables are heavy feeders and deplete the soil more than others. 

Nitrogen fixing Rhizobia
nodules on Fava Beans
For example, heavy feeding varieties like tomatoes, corn or squash should be followed by lighter feeding leafy varieties like lettuces and or root crops such as carrots. Then we follow that second crop with a with soil-building legume crop like beans or peas were a fall cover crop like bell or fava beans.
Legumes actually enrich the soil because their roots have nodules containing nitrogen fixing Rhizobia bacteria that convert the nitrogen from the air and make it available for the plant to use as food. These nodules are very noticeable when you pull up a plant by the roots and look carefully. After our legume crop is cut and harvested, the remaining roots are left in the ground or composted so the root nodules will break down and release all the valuable fixed nitrogen for following crops.
Garden map for planning
crop rotations
For example, Nightshade family vegetables are susceptible to soil pathogens like verticillium and fusarium, so it is helpful to rotate their place in the garden each season.

Rotating varieties of the Mustard family helps us avoid build up of soil dwelling cabbage maggots and other mustard family pests. We keep a simple chart of our garden bed plantings each season so that we can easily keep track of what the next rotation should be.  

Cover Crops Offer Nutrients and Protection
Turning in cover crop
Planting cover crops is a great way to protect soil from erosion from winter weather and rain. When our growing season slows as winter draws near, final harvests are made from those beds we will not be planting again until spring. We protect this uncovered soil by planting a cover crop to both enrich the soil and protect it from the elements. In our area we use Pacific Gold mustard and a legume crop like fava or bell beans, or a blend of oat grass, bell beans and purple vetch works best. (Cover crop components vary in each region of the country: consult a local Master Gardener or knowledgeable staff at a good independent garden center to find out what is best used in your area).

The cover crop also takes up extra nutrients in the soil that would otherwise be leached out by driving rain. In spring, the cover crops can be dug back into the soil, thus releasing the captured nutrients. In our trial garden, we do this mainly with Pacific Gold mustard which is low growing and easy to dig back into the soil. It also has a more powerful effect against soil diseases when allowed to decompose directly in the soil. Other cover crops like legumes which grow much larger, we prefer to pull out and compost the cover crop plants. They will break down in the compost heap much faster this way, so their nutrients are ready to be added back into the garden beds as part of the compost added when we prepare for planting spring. 

Part 2 of this article will be published next month.
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