Jersey City Raised Bed Gardening Workshops
Introduction
Raised beds, also called garden boxes, are frames made out of material such as wood, metal, or plastic that contain topsoil for growing plants. The main purpose of using raised beds is for food safety. Growing vegetables in raised beds prevent the uptake of contaminants from the soil in the ground. The soil in Jersey City, like many other cities with industrial history, can contain toxic levels of contaminants such as lead, arsenic, and cadmium.
The 2024 Adopt-A-Lot lease agreement requires raised beds be used to grow consumable plants. Here are the sections in the lease agreement where raised beds are mentioned:
- Section 3.D.a: Lessee shall design and install a plant garden according to city guidelines for raised bed plantings for consumable foods.
- Section 3.E.a: Lessee shall design and install a plant garden. If plantings are for consumption they must meet the City’s guidelines for raised bed plantings.
- Section 3.F.a: Lessee shall maintain the Garden in a safe condition and take care of all plants and structures contained therein, including all fences, raised beds, tables, benches, and ornamental items.
Besides the food safety reasons for growing in raised beds, they can also be beneficial to have better control of the condition of the soil plants are grown in. Also, raised beds help with accessibility for gardeners with limited mobility.
Cost is an important factor in planning for raised beds. The more raised beds you can build at once, the lower the overall costs will be. To give an example, here is the cost breakdown for the single 4'x4' with 22" in height wooden frame raised bed used for this workshop:
- Wood (8 10' length pieces): $200
- Linseed oil: $40
- Paint brush: $9
- Screws: $11
- Landscape fabric: $27
- Topsoil (1 cubic yard): $32
- Truck rental: $111
Total: $430
Location and Dimensions
Sun Exposure
The most important part of choosing a location for a garden bed is determining how much sunlight there is. A minimum of six hours of direct sunlight is required for most common garden plants. However some garden plants can still do well with less direct sunlight such as spinach, kale and swiss chard, and root vegetables such as carrots. In the northern hemisphere, the best locations for sunlight will be ones with southern exposure. It is important to consider things that will obstruct planting sights from sunlight such as buildings and trees.
The best solution to find out how much sunlight exposure different areas in your garden gets is to observe throughout the day. Dedicating an entire day to observing sunlight may not be possible to all site operators. It is suggested that site operators organize a community sun observation days on days there are little or no clouds. Designate times for garden members to draw a map or fill out a chart of what they observe. The sun’s positions in the sky will vary throughout the year so for a complete analysis, observations should be done during each of the four seasons. There are also software tools to help estimate sun exposure in different locations, refer to this guide for more details.
Paths
Besides sunlight, accessibility for all community members is the next most important factor in choosing a location for garden beds. Garden beds should be placed where it is easy to reach all areas in the bed without having to walk onto the bed itself. Space for pathways around garden beds should be considered as well. Paths should be seeded with a cover crop such as grass or clover, or mulched with 3” depth of large wood chips or gravel, or paved with bricks. Covering paths is important for minimizing dust which is a major vector for soil contaminants. Dust should be avoided because it can be breathed in, tracked on shoes back to peoples homes, and land on vegetables. There are many considerations for accessible path design for community members in wheelchairs (36 inches) and wheelbarrows (24 inches). Refer to the NYC Parks GreenThumb Community Garden Accessibility Guide for detailed information.
Pests
Rodents such as rats and mice like to make burrows and move around in well hidden locations. To make your raised beds not an ideal habitat for rodents, make sure not to place raised beds in locations that can make small narrow passageways such as along a fence. Ideally the raised beds should have paths on all four sides and placed in areas of your garden with lots of foot traffic to help deter rodents.
Dimensions
The area (length and width) of raised beds can vary based on space available in your garden after considering sun exposure and path layout. You never want to have to walk into your raised beds in order to tend to them. A general rule of thumb is raised beds should be no wider than two feet from an adjacent path. For example, if you are able to have paths on either sides of your raised bed, it can be four feet wide. If you are only able to have a path on one side of the raised bed, it should only be two feet wide so you can reach all areas of the bed from the path.
The raised bed depth depends on what types of crops you plan on growing in them. Some crops require less root depth than others. Refer to this guide for the root depth requirements of common garden vegetables. If you want to make all your raised beds one depth, a good size would be 17 inches to support optimal root growth for most types of garden vegetables. Otherwise you could make raised beds of varying sizes for different types of crops.
Special consideration should be made for community members in wheelchairs, refer to the guide mentioned in the Paths section above.
Materials
Frame
The most important factor in choosing a raised bed frame material is making sure it is food safe. The recommended raised bed frame materials are metal, wood, plastic, or stone. Frames should last between 10 to 20 years if constructed properly.
Wood is the most cost effective option for raised beds. NYC GreenThumb’s standard lumber is untreated Douglas Fir sized 2”x10” at 8’ lengths. However, cedar is a better wood as it will last longer but it costs more.
Although treated wood is more rot resistant, it is not recommended because it can leach chemicals into the bed’s soil, especially when the wood is cut which exposes more chemicals. However, treated wood manufactured later than 2004 does not contain extremely toxic chemicals such as arsenic and chromium. It is recommended to apply a food safe wood sealant such as raw linseed oil. If you wish to paint the exterior of your raised bed frame, be sure to use VOC-free paint.
The screws used for raised beds should be rated for exterior use which means they have rust proofing (galvenized or stainless steel). If using plastic frames, make sure to use something food grade such as BPA and phthalate-free vinyl.
For the workshop, I purchased wood at Dykes Lumber in Weehawken for the frame. I got untreated knotted Western Red Cedar 5.5"x1" at 10 foot lengths (Item# 546CD). They cost $2.48 per foot which was significantly cheaper than non-knotted cedar which was about $12 per foot. I was able to build a 4'x4' frame that was 22" high with 8 pieces of this wood. I had to tie down the trunk door of my car with twine to get the wood to fit. I sealed the wood with raw linseed oil.
Base
The base the of the raised bed should be made out of a material that will keep soil in the ground from getting mixed in with clean soil in the raised bed. It is important that the base material is able to properly drain water so the soil in the bed does not get too wet. Landscape fabric is a great material to use as the base of a raised bed. Another alternative is gravel.
Topsoil
Topsoil, also known as mineral soil, should be sourced from a supplier that has certified clean soil. For filling raised beds, bags of topsoil are not cost effective. It’s much cheaper to buy by the cubic yard (yard for short). A cubic yard of topsoil is equivalent to 36 bags (40 lbs, .75 cubic feet). A raised bed that is 4'x4' in area and 20" in height requires 1 cubic yard of soil to fill.
Compost is not a replacement for topsoil because it does not contain all the nutrients plants need. Also, compost does not have the right structure to stay aerated (roots need oxygen) and will get compacted over time. Potting mix can be used as an alternative to topsoil since raised beds are a form of container gardening. However, you can usually only find bags of potting mix so it is not cost effective.
For this workshop, I purchased topsoil from Nature’s Choice Corporation in North Arlington. Nature’s Choice topsoil is certified clean because it is “NJDEP approved; meets NJ Residential Soil Criteria.” Nature’s Choice will also provide soil test results for nutrient levels if requested. Their price is $32 per cubic yard. I rented a flatbed truck from Home Depot to pick up the topsoil which cost $111 for 4 hours. Note that the truck is rated for 3000 pounds and a cubic yard of soil can weight anywhere from 2000 to 3000 pounds.
Construction
First prepare the site for the raised bed by leveling the ground by first tilling then smoothing out with a rake. Then, tamper soil to compact it. Wear masks when working with the soil in the ground to avoid inhaling dust. Build the layers of the frame on a level surface by screwing the frame material together. Make sure to drill pilot holes before drilling the screws to avoid splitting. Use a 90 degree angle clamp to ensure the corners of the frames are square. If there is more than one layer of frame being stacked, attach vertical pieces at appropriate places, like the corners, to connect the frame layers together for stability. Lay down the base material first before moving the frame into place on the site. If you are using landscape fabric as a base material, make sure to put down two layers.
Maintenance
Wooden frames are expected to last about 10 years, metal ones 20 years. Wooden frames can have individual pieces replaced as they get older. Raised beds can always be built up higher at a later time to accommodate plants that require more soil depth.
Gardening
Keep at least two inches of mulch on top to help regulate moisture and temperature of the topsoil. Finished compost can be used as a mulch. An inch of compost should be added each year.
Use the square foot gardening technique to plan out what you will grow.
On top netting can be added to keep pests off your vegetables. Also a cold frame can be placed on top for winter gardening.
It is very important to wash all produce from your garden before eating to remove any potentially contaminated dust.
