Materials and supplies

Soil

Soil is one of the most important resources for your school garden, whether you are filling new raised beds, amending existing raised beds, starting seeds, or growing in containers. The type of soil that you need depends on how it will be used. 

How much do you need? Bagged Versus Bulk. 

Before you buy, figure out how much soil you need. Use this calculator to estimate quantity. Depending on quantity, you'll want to decide if you are going to buy in bulk (several yards of soil delivered to the school), or if you would prefer bagged soil picked up from a local retailer. While bulk soil is more economical for large quantities, suppliers often charge a fee for delivery and have a minimum order size, so bagged soil can make more sense for small quantities.  Keep in mind that 1 cubic yard of soil is 27 cubic feet. This works out to about 18 bags that each hold 1.5 cubic feet. Not only will this likely cost more than a cubic yard of bulk soil, but it can be difficult to transport without a pick-up truck. 

Raised Beds:

For filling large raised beds look for a bulk soil that contains a mix of topsoil and finished compost. Some companies sell soil products that are labeled as "raised bed soil," and these products can also be a good choice. It's not generally a good idea to use only screened topsoil in a raised bed. Often, this soil does not contain a lot of nutrients, and will compact easily in the bed causing drainage issues overtime. 

Local Suppliers:

• Home Depot and Lowes: Both companies sell bagged raised bed soil in 1.5 cubic foot bags. This can be a good option for small projects. For example, 1 raised bed that is 4 feet long, by 3 feet wide could be filled with 10 inches of soil using seven of these bags, which could easily be transported in most large cars or SUVs.  

• Hollins Organic: Hollins Organic on Falls Road in northern Baltimore offers bulk delivery of a raised bed soil mix that is a combination of pine bark fines (for aeration), pure grow (a finished compost product), and screened topsoil. They have a 3 yard minimum order for this product, and can deliver locally. Products can also be picked up in a truck or trailer from their Falls road location. Their delivery prices depend on quantity and zip code, so please call for a quote. 

• Camp Small: Camp small is Baltimore City's waste wood reclamation site. They often have compost available for bulk delivery at $18/yard plus delivery fees. This product would be suitable both as a soil amendment, and to use as a raised bed soil. 

• Maryland Landscape Supply offers a garden soil product that is a blend of composted leaf material and topsoil that would be appropriate for raised beds. 

Pots

For filling smaller containers like pots or windowsill boxes, the best choice is a bagged soil from a local retailer that is labeled "potting mix." These soils often contain a mix of light weight materials to promote aeration and drainage (such as peat moss, coconut coir, and vermiculite). Some mixes also contain fertilizer and nutrient-rich materials. The lightweight nature of potting mix makes it perfect for small pots and containers, because it allows plant roots plenty of access to air. If you intend to grow a larger fruiting plant in a container (such as tomatoes or peppers), be sure your potting mix contains a good source of nutrients, or mix in a couple handfuls of finished compost (also available as a bagged product from Home Depot, Lowes, or other local retailers. 

Seed Starting

Soil that is labeled as either seed starting mix or potting mix is suitable for germinating seeds in small pots or containers. Seeds don't initially need nutrients to grow, so it is not necessary to have a media that is rich in nutrients or to fertilize young seedings. In fact, too much additional fertilizer can damage young seedlings. 

Many schools choose to cover the surface of the ground surrounding their raised beds with a woodchip mulch. A thick layer of woodchips can prevent weed growth, and eliminate the need to mow between beds. Many of the suppliers that offer soil, including Hollins Organic, Camp Small, and Maryland Landscape Supply also offer woodchip mulch. The most affordable option, is to check with Camp Small to see if they have Arborist Chips available. These woodchips are coarser than a finely ground landscape mulch, but they are perfectly suitable for surfacing the ground between raised beds. Camp Small offers these to schools for only the cost of delivery. 

Note, whatever type of mulch you use, plan to reapply it annually in order to maintain a thick layer to prevent weed growth. This is generally a great task for a community volunteer day. 

Lumber

When it comes to building raised beds there are many options. First, reach out to the team at Great Kids Farm (farms@bcps.k12.md.us) to see if they have any raised bed kits available for schools. 

If not, consider either building your own raised beds, or shopping around for a pre-made kit. The best option depends on your budget and your skill level. It's also important to carefully chose the materials you use to make raised beds.

Pressure treated and naturally rot resistant wood species (such as cedar) are both good choices for lumber, and can last for many years. Untreated wood species such as pine will likely rot in only a few years if left unfinished.*

Exercise caution when using certain reclaimed materials for constructing gardens, as they may have residues of chemicals that can be harmful to your efforts. For example, do not use railroad ties for raised bed garden construction due to chemical residues. For information on the safety of reclaimed materials, consult the University of Maryland Home and Garden Information Center.

Finally, if you are building your own raised beds, note that many suppliers will cut lumber to size at the store. 

The following links can help you find free or inexpensive materials:

• Camp Small often has rot resistant lumber available for sale at reduced price for schools. 

• Baltimore Community Toolbank allows organizations and schools to borrow tools at very low cost for community projects. Joanna Pi-Sunyer manages a City Schools membership, so please contact her at green@bcps.k12.md.us if you would like to borrow from the Toolbank.

• Station North Tool Library provides individuals with affordable access to tools and skill-building workshops.

• The Loading Dock and Second Chance are local nonprofit organizations that sell inexpensive reused building materials, and host workshops on using reclaimed materials** for building projects.

*A note on the safety of pressure treated lumber: Pressure treated lumber is treated with chemicals to make it rot resistant. This has raised concerns that chemicals in the lumber could leach into garden beds and be absorbed by plants, posing a risk to human health. For many years, the primary chemical of concern was Arsenic. In 2004, the EPA restricted the use of Arsenic in pressure treated wood products. While the issue is still controversial, research has shown that the leaching of chemicals from modern pressure treated wood products is not absorbed by plants in quantities that would pose a health risk. For more on this, see this answer from Oregon State University, and this fact sheet from Penn State University.