Assessment

Though there is a lot you can learn about a parcel’s history through research and due diligence, nothing beats going out and taking a look yourself. This is encouraged for every type of project no matter what the circumstances.

When making a site visit, bring a few tools with you – a notebook, camera, shovel to poke around the dirt, and some clippers to take a sample of any growth you can’t identify.

Soil Quality

Before investing your time and energy in one vacant lot, it’s best that you test the soil first. A soil test can tell you the amount of nutrients in the soil, and whether there is contamination from harmful metals like lead in the soil. This is particularly relevant if you plan to grow food on a vacant lot, but any vacant lot should be tested before many people come in contact with it.

You can begin by checking out some simple visual cues. Soil that is healthier tends to have a darker color and lots of plant life. On the other hand, contaminated, nutrient-poor soil may be gray in color with little plant growth.

You can either send your soil to a lab to be tested, or purchase your own soil-test kit. The first option is less expensive (about $15) while the second option is a little more pricey.

Soil under turf

To collect soil from your lot to send to the lab, follow the following steps for the best results:

  1. Screen Shot 2015-04-08 at 3.29.15 PMYour sample should represent the entire space that will be used on your vacant lot.  One way of ensuring this is by measuring out a grid on your lot. Measure every 10 feet around the edges of your lot, dividing your lot into 10 feet x 10 feet squares. Use a trowel or shovel to take a small sample from each of the 10 ft square sections. When you combine all of the samples, you should have about one cup total of soil to send in to the lab.
  2. Dry out the soil by spreading it out on a newspaper for a few days. When it’s dry, put it in a sealable plastic bag.
  3. We recommend that you send your soil samples to the University of Massachusetts’ Soil and Plant Tissue Testing Laboratory. Click here to find their soil sampling information.

Understanding Soil Testing Results

  • Soil pH: Soil pH is a measure of acidity or alkalinity in soils between 0 (most acidic) and 14 (most alkaline).  Many natural processes are affected by the pH balance, including toxicity, bacteria, and available nutrients.  Soil pH between 5.5 and 7 is ideal for plant life as it supports the most nutrients and is generally easily worked rather than sticky or difficult to cultivate.  If soil is not within ideal pH ranges, ground limestone can raise pH levels while sulfur can lower them.
  • Aluminum (AL):  Aluminum is the most common metal in the earth’s crust, yet it is not an essential element for plant or animal life.  In fact, too much aluminum is toxic to plant life in particular.  Aluminum toxicity typically occurs in highly acidic soil (pH 0.0 – 5.0) and often occurs alongside nutrient deficiency due to the pH acidity.  As such, a soil pH below 5.0 should raise questions about a plant’s vulnerability to high aluminum toxicity.  High levels of aluminum often result in shorter plant root systems, which means less water intake for plant life.
  • Organic Matter: Soil organic matter is a measure of the amount of decomposing plant and animal residues, cells, tissues and other substances.  It is highly important for soil quality. Ranges between 4% and 8% are ideal for plant life.  When within the 4-8% range, soil holds water and nutrients better, allows for stronger root growth, and is easier to work.
  • Phosphorus (P):  Phosphorus is an essential nutrient for plant life, especially for food and flower gardens.  Soil pH near 6.5 allows for the most availability of phosphorus.  Ideal levels of phosphorus typically fall in the medium range from 10-20 parts per million (ppm).
  • Potassium (K):  Plant life requires a large amount of potassium for health and production.  Ideal ranges of potassium are typically 120-200ppm, but slightly lower or higher numbers may be suitable depending on the amount of plant growth on the land.  Soils with a more acidic pH (less than 5.0) often have potassium deficiency.
  • Calcium (CA):  Calcium is a nutrient that is important for a plant’s ability to regenerate cells and take in other nutrients through its roots.  Soil that lacks adequate calcium often produces fruits and vegetables that rot.  The ideal range for calcium in soil is between 600-4000ppm.
  • Magnesium (MG):  Magnesium is a nutrient that is important in the development of chlorophyll, the green pigment in plants that allows them to absorb energy from light (photosynthesis).  The ideal range for magnesium in soil is between 60-500ppm.
  • Cation Exchange Capacity:  Cation Exchange Capacity (CEC) is a measure of the soil’s ability to hold nutrients (calcium, magnesium, potassium, etc.).  The level of CEC depends on the amount of clay minerals and organic matter in soils with higher levels of CEC meaning more clay and organic matter.  CEC is measured in milliequivalents per 100 grams (meq/100g) with most soils falling between 2-35meq/100g depending on the type of soil.
  • Percent Base Saturation:  The Percent Base Saturation is the portion of CEC containing a certain cation (an ion in the soil with a positive charge such as calcium, magnesium, or potassium). The percentages must fall within specific ranges to create the best plant growth potential.  These ranges are 1-5% potassium, 10-40% magnesium, and 60-80% calcium.
  • Boron (B): In soils, Boron is an essential micronutrient that is vital to plant growth and cellular reproduction.  The ideal range for boron in soil is between 0.5-2.0ppm.
  • Manganese (Mn):  Not to be confused with Magnesium, Manganese is a vital micronutrient for plant growth as it aids in chloroplast formation and photosynthesis.  Ideally, manganese should be above 1.5ppm.
  • Zinc (Zn):  While zinc is an essential micronutrient for plant growth, the specific role of zinc is not exactly known.  The ideal amount of zinc within soil should be greater than 1ppm.
  • Copper (Cu):  Copper is an important micronutrient for plant growth as it helps plants form chlorophyll and promotes seed production.  The ideal amount of copper found in soil should be above 0.6ppm.
  • Iron (Fe):  Iron is a highly important micronutrient for plant growth that is used in the production of chlorophyll.  Iron deficiency can cause leaves to turn yellow (chlorosis), especially in young leaves.  The ideal amount of iron varies greatly depending on the type of plants, so it is important to know specific plants’ iron needs.
  • Sulfur (S):  Sulfur is an important micronutrient for protein conversion and chlorophyll production.  Ideal levels of sulfur depend on the structure of soil and the plants growing within it.  For example, soil low in organic matter is more likely to be sulfur deficient.
  • Lead (PB):  Lead is a natural occurring element in soils, yet at higher levels, it is a contaminant that can jeopardize the health of your plants and those who use the lot.  Typically, most soils will contain 5-100ppm of total lead.  While levels higher than this range do not necessarily mean lead contamination, it is worth considering for what purpose the garden is being used.  The Environmental Protection Agency (EPA) considers over 400ppm to be dangerous, but lead levels outside the normal range might mean using lots as flower gardens instead of food gardens, especially with the risk that food plants may become contaminated with lead.
  • Chromium (CR):  Chromium is a natural occurring element with a variety of human-made variants.  Often the result of manufacturing processes (such as stainless steel), human-made variations of chromium are potential harmful to plants, animals and humans.

Sun Exposure

Sun Exposure is the amount of sunlight a lot receives daily. This can depend on how the lot is oriented, slope, and shade caused by trees or adjacent buildings. You could either look for a lot that has sun exposure which suits the types of plants you’d like to grow, or look for plants that suit the sun exposure of the lot you plan to use.

Graphic of sun exposure

Because of the earth’s tilted axis, in Allegheny County the sun is always in the southern part of the sky during daytime. Because of this, vacant lots will receive the most sun exposure if they are on a south-facing slope or on the south side of shade-producing buildings and trees.

When purchasing seeds or plants, make sure to check their labels or ask how much sun exposure that plant needs. The amount of shade or sun that it needs may be labeled as follows:

  • Full shade – North side of buildings, under dense trees, in the woods. No direct sunlight on the ground.
  • Partial shade – May only receive sunlight during one part of the day for a few hours. Does not receive midday sun.
  • Light shade – May receive sunlight during part of the day for several hours. May be under a tall tree or a tree with sparse foliage.
  • Part sun – May receive sunlight during parts of the day, and can tolerate midday sun.
  • Full sun – Receives direct sunlight for at least 6 hours or more each day, including some or all of the midday hours.

Here is a resource to help you assess how much light will work for you

The following signs can show that a plant isn’t getting enough light:

  • Growth is sparse
  • Stems are lank and spindly
  • The distance between leaves where they’re attached to the stems is wide
  • You see fewer flower buds and fewer flowers
  • The entire plant leans toward the source of light

The following signs can show that a plant is getting too much light:

  • Flower petals dry out
  • Leaf edges look burnt or dried
  • Flower color looks faded or washed out.
  • The entire plant starts to weaken and droop
  • More Information

Water Access

Stormworks rain barrel

As you begin choosing a lot to work on or designing your lot, consider the availability of water for watering plants on the lot. A few ways of accessing water on a vacant lot are listed below. If no water connections are available, design your lot using native plants that can tolerate dry conditions. The Pennsylvania Department of Conservation and Natural Resources has a great resource to find native plants that are best for your lot.

Ways to connect your lot to water:

  • The owner of an adjacent building may allow access to their outdoor spigot.
  • The owner of an adjacent building may allow rain barrels to be attached to their downspouts to supply water
    • A rain barrel is a container that captures water from a downspout connected to a rooftop
  • Request that the Water and Sewer Authority of your city or municipality installs a water meter on your lot.
  • Learn more on the website of 3 Rivers Wet Weather.

As you begin to design your lot, there are many considerations that can help save water.

  • Planning and design: Your lot contains many microclimates (an area with distinct levels of sun exposure, humidity, and soil type), which affect which plants grow best there. Choose your plants based on your knowledge of the lot’s microclimates to conserve water.
  • Know your soil: If you know the ability of your soil to hold water, you can choose plants accordingly. Your sites may have spots with damper soil as well as spots with water runoff. While the addition of compost and mulch can improve the ability of the soil to hold water, it’s important to consider what you’re starting with.
  • Avoid lawn grass: Because of the short root-system of most lawn grass, it doesn’t have a large capacity for holding water. If one of your goals is to keep stormwater from running off of your site, consider plants with deeper roots like native  perennial wildflowers and trees.

Slope

Slope

If you live in Allegheny County, chances are you’re familiar with life on a slope. Consider the slope of your vacant lot as you make a design. Some sites may have low areas that hold too much water. Other sites may have steep banks that need some stabilization.

If your site has low areas that hold water, consider planting techniques that can take advantage of that wet soil. For example, you could try a rain garden. If your site has a steep bank, one low-maintenance, and low- or no-cost way to prevent erosion is by using Hugelkultur.

Hugelkultur is a way of mimicking what a forest does to stabilize slopes – fallen branches and woody plant material pile up, create a damp area for plants to grow, ultimately preventing erosion by slowing down the flow of water with plant roots.

Plant Growth and Maintenance

Tree care: Many urban vacant lots have trees that need to be cared for. Trees can be a safety hazard, and can fall on electrical wires or the street if they are un-cared for. Invasive vines, which are often found on trees in vacant lots, can cause damage to trees if left to grow. The forester for your municipality or city can be called for advice on safely managing trees on the site.

Tree on hill overlooking Pittsburgh

Trees on your vacant lot can be a blessing or a curse depending on what you plan to do with your lot and the health of the trees. As you likely know, in the City of Pittsburgh, you can live in the city and the forest at the same time. A healthy urban forest has many advantages, like producing the oxygen we breathe, taking pollutants out of the air, preventing erosion, decreasing runoff, having a cooling effect, reducing traffic speed, increasing property values, increasing profits for adjacent businesses and improving safety for pedestrians. However, if the trees on your vacant lot are not in a healthy condition, you will need to spend some of your project budget on having a forester manage your trees. Perhaps the trees on your lot are diseased, are being strangled by invasive vines, or have fallen limbs. These issues all require a little more attention and money.

To learn more about this area’s urban forest, check out Tree Pittsburgh’s Urban Forest Master Plan here.

Litter and Dumping

Litter is a common problem in urban areas, particularly in and around vacant lots. Vacant lots give a message of neglect to passersby, ultimately making people feel less guilt for littering. Apart from simply looking bad, litter can cause some serious issues. When it rains, litter often ends up in storm drains, clogging up the sewer system. This exacerbates the combined sewer overflow issue in Pittsburgh, and eventually pollutes rivers. Litter also can attract rodents to an area, which can spread diseases and cause other nuisances. When cans, bottles, paper, and many other types of materials are littered, they do not enter into the recycling system. This means that new bottles, cans, paper, etc. must be produced from virgin materials, rather than recycled materials.

Apart from refraining from littering personally and picking up litter in your own neighborhood, you can organize a neighborhood-wide cleanup event. The City of Pittsburgh, for example, has a program called “Beautify Our ‘Burgh” which groups can participate in to get resources and recognition for litter-cleanup. If you live in Pittsburgh, check out their webpage for more information and contact info.

Litter in a vacant space between buildings

Dumpsites, as opposed to litter, are areas where a large amount of trash is dumped, either as a one-time event, or a recurring issue. Dumpsites may consist of landscape debris, tires, furniture, electronic waste, construction waste, or other materials. Allegheny County is lucky to have an organization called Allegheny Cleanways which engages and empowers residents to eliminate illegal dumping in their community. If there is a dumpsite in your community, you can work with Allegheny Cleanways or the Department of Public Works to get the site cleaned up.

Do you have a vacant lot in your neighborhood that needs to be cared for? If you don’t own the lot or have permission from the owner of the lot, there are a few ways to approach the issue. In the City of Pittsburgh, If you don’t personally know the owner of the lot, you will need to contact the 311 Response Center to ask for the Department of Public Works to clean it up. They will ask for the address or intersection that the lot is on and what specific issues there are with the lot.  If you do know the owner, simply ask for permission to clean it up.

Dumpsite within the city

Invasive Species

Invasive plants thrive in habitats with low soil quality, because they out-compete native plants. Because most urban vacant lots used to have buildings on them, the soil quality can be poor, creating a perfect habitat for invasive plants. Without regular maintenance, invasive plants will spread within and around the lot. If there isn’t the resources to care for the whole site, a foot or two around the edge of a site can be mowed, weed-whacked, or mulched to prevent plants from leaning over onto the sidewalk or street.

Many vacant lots are filled with invasive plants. Invasive species are plants (or animals) that are not native to the environment they are in, and as a result can spread rapidly and disrupt the native ecosystem. Invasive plants can often tolerate low quality soil, like the soil in most vacant lots. This makes it easy for them to take over the other plant life in a lot. To get you started on your fight against invasives, check out the three examples below which are some of the most common invasives in the area. For more information, check out the Pittsburgh Parks Conservancy’s extensive guide to invasives in Pittsburgh.

Japanese Knotweed

Knotweed is the most voracious of any invasive plant in this area. It is very difficult to get rid of, and spreads quickly. Originally from East Asia, Knotweed was introduced to the US in the late 1800’s. It grows in thick masses of stalks. Small pieces of the roots can sprout new plants when uprooted. To get rid of this tricky invasive plant, you can use a shovel to remove the existing stalks, then cover the ground with a thick layer of cardboard or landscape cloth and mulch.

Japanese knotweed flowers
Japanese knotweed spreading in a lot
Japanese knotweed along a wall

Garlic Mustard

Garlic Mustard doesn’t look particularly aggressive – in fact, this herb was originally grown as a food crop. However, it comes back year after year with a vengeance if not carefully controlled. Garlic Mustard can be removed by hand, and discarded in trash bags to kill the plant before it produces seeds.

Garlic mustard blossoms
Garlic mustard closeup

Tree of Heaven

Don’t let the name of this invasive plant trick you. It has spread far beyond its original range in China to Europe and the Americas. Like Knotweed, the Tree of Heaven is often found in vacant lots because it prefers disturbed, low quality soil. In these types of soils it doesn’t have to face as much competition with other plants. To get rid of Trees of Heaven, you can cut the trees before they come too large, particularly in the early summer when the root reserves are low, and you can plant trees nearby that would shade out the Tree of Heaven.

Closeup of tree of heaven blossom
Tree of heaven

To learn more about invasive plants in our area, check out the Pittsburgh Parks Conservancy’s “Invasive Plants of Pittsburgh” guide. Another great reference is the Penn State Extension.

Existing Infrastructure and Utilities

Most vacant lots had houses sitting on them at one time. This means there may be old infrastructure on the site. Sometimes this infrastructure is above ground and visible. Perhaps there is a set of stairs, a concrete pad, or a retaining wall remaining on the site. In some cases, you may be able to integrate these elements in your project design. However, if the infrastructure is damaged in some way, it might be best to work around it rather than incorporating it.

There may also be some remaining infrastructure that is underground on your site. If your project involves digging or moving earth with power equipment, state law requires that you notify underground utility companies three to ten business days before you plan to dig. You can call PA One Call at 800.242.1776.

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