Mulching is important for landscapes at all times of year. Mulching helps:
- Reduce weeds
- Maintain soil temperatures
- Retain moisture
- Enhance the beauty of the landscape with many natural choices
- Provide constant supplies of organic matter as mulch decomposes
Most landscapes benefit from a 2-4” layer of mulch.
The soil is the source of beneficial organic matter and texture to grow highly productive plants in all gardening uses. Four simple steps to improve your garden soil includes:
- APPLY a 2-4” layer of soil amendment, such as Garden Soil or a compost-based soil amendment
- MIX to a 6-12” depth to incorporate the soil amendment thoroughly with mineral soils
- SMOOTH with a rake or roller
- PLANT seeds, seedlings, vegetables, herbs, flowers or ornamentals, then thoroughly water after planting
Soil Composition 101
Some gardeners are lucky enough to have a nearly perfect soil, but for most of us that’s not the case. Understanding the components of healthy soil structure can help you manage the environment underground, and put on a good show above ground. Soils are comprised of weathered rock and minerals, organic matter, organisms, water and air. These components are crucial for healthy plant growth.
• Mineral Soil: Minerals are the structure of our metaphorical soil apartments and provides the playground for materials to move. Mineral soil is composed of sand, silt and clay particles. It’s what forms the texture of the soil.
• Organisms: These are the dwellers of our happy soil apartment homes. These are the friendly organisms such as worms, insects, bacteria, fungi and nematodes that help add nutrients to your soil. They facilitate getting nutrients to the plants and also create porosity in the soil.
• Organic Matter: Organic matter is like snack packs scattered throughout the soil apartments, especially in the top layers. Specifically, organic matter is decomposed organic material such as leaves, wood chips, food scraps, grass clippings and other vegetative matter. Although organic matter often only makes up 5 to 10 percent of the soil, it is absolutely essential for plant growth! Organic matter is basically the food for microorganisms and other forms of soil life. Food is important; make sure to feed your gardens with organic matter to give them an extra boost!
• Water & Air: Finally, the components we rarely consider yet are absolutely essential for soil health: air and water. It’s the ductwork and plumbing that gets everything flowing. A healthy soil is about 25 percent air and 25 percent water. This is needed for organisms to survive.
Soil Apartments: Building Great Soil Structure.
Just like neighborhoods, every soil is different. Imagine if you will, that the soil is series of “soil apartments” underneath our feet.
Simple steps you can do to improve your soil structure:
• Add organic matter: Apply Garden Soil, compost-based soil amendments, or layers of mulch that break down over time.
• Aerate your soil: Fluff it up and let air (and roots, worms, microbes, etc) flow!
• Create pathways: Reduce compaction by keeping foot traffic to designated spots
• Water deeply, less often: Instead of watering quickly and frequently, instead water deeply less often. This encourages root growth and benefits the plants by decreasing the moisture on the leaf area that encourages fungus to establish.
Raised beds are the hottest trend in gardening and take gardening to another level by improving drainage and creating attractive and organized garden structures. There are hundreds of raised bed options – from wooden kits to stone pavers to human ingenuity. Select the system that meets your need by answering the following questions:
- How much space do I have available?
- What are my primary goals? Examples include controlling weeds, upgrading poor mineral soil, growing certain plants; installing easy irrigation plans.
Generally speaking, raised beds built on existing soils are built 6”-10” high.
For new construction:
- BUILD your raised bed system
- FILL to within 1” of the top with high quality soils. Frequently it’s a blend of Potting Soil, Potting Mix, Soil Amendments, Peat Moss and compost-based products. Make sure the soils are blended well.
- WATER and allow the soil to settle. Then top off to get back to the desired height.
For existing raised beds:
- APPLY a 2-4” layer of soil amendment, such as compost, or Potting Mix
- MIX to a 6-12” depth
- SMOOTH with a rake or roller
- PLANT seeds, seedlings, vegetables, herbs, flowers and ornamentals, then water thoroughly after planting
- Aeration – light and fluffy texture allowing air to flow through the soil to keep the friendly organisms in the soil healthy and working for you;
- Drainage – good soil structure that allows water to move through and not create root rot;
- Nutrient retention – soil structure that binds or holds onto minerals
- Water Retention – moisture holding capacity to efficiently hold or release water when called on by the plants, to ensure a good use of a very important natural resource.
Trees and shrubs benefit from both proper soil preparation under the roots, as well as ongoing maintenance above the ground.
For planting new trees and shrubs, follow the following steps:
- DIG a hole 2-3x the diameter of the root ball
- MIX 1 part soil amender plus 2 parts mineral soil (the soil already in the spot where you dug the hole)
- PLANT the tree or shrub 1” above grade and add soil mix under and/or around the root ball. NOTE: It’s very important that the top of the root ball is at the same height as the existing mineral soil.
- WATER thoroughly after mulching the surface with the remaining soil mix
A Rain Garden is a planted depression where run-off from roofs, driveways and other surfaces is directed so that it can soak back into the soil naturally rather than run into storm drains. The soil and plants in these areas filter out some impurities before the water drains into sewers, groundwater, rivers and streams.
CHOOSING A LOCATION: Choose a spot where water can be easily directed through the landscape or from downspouts. Make sure to leave at least 6 feet from your house, and allow for overflow away from foundations and other structures.
SITE AND SOIL PREPARATION: Amend the soil so the mix is roughly 50% native soil, 30% soil amendment or compost-based product, and 20% pumice.
MULCHING: Two kinds of mulch are important in a rain garden. A mulch of pea gravel or river rocks at the point where water enters will help prevent erosion; this mulch should be thick enough that no soil shows through. The rest of the rain garden should have a high-quality soil amendment or compost-based product 1-3” deep added once a year as spring rains taper off. This will help suppress weeds and maintain moisture levels during dry periods.
WATERING: All plants (even drought-tolerant ones) will need supplemental watering the first 1-2 years until they are well established.
FERTILIZER AND PESTICIDES: These should both be avoided in your rain garden whenever possible; part of the goal is to help keep these synthetic chemicals out of local waterways. If necessary, use granular, low phosphorous, organic fertilizer, and the least toxic pesticide available. Plant selection is critical; consult with the nursery specialist for plants that will thrive in this environment.
NOTE: Thank you to Portland Nursery for this information.
Streetscapes, or Bioswales, are linear depressions that direct the flow of water while letting it percolate into the soil.
Dry – The top where floodwaters never reach. Drainage here is good because it’s at the top of a slope.
Mesic – This level, just below the dry zone, experiences occasional, brief winter flooding and summer drought.
Moist – The zone approaching the bottom that experiences frequent winter flooding. The number of plants that can grow here without summer water is limited.
Wet – The bottom of the swale will be saturated for a large portion of the year; water plants can be grown here if supplemental water is given in the winter. Without summer irrigation, fewer plants can grow here.