Grow bags are an increasingly popular option for gardeners seeking a flexible, portable and affordable way to garden. They are fabric containers made of heavy felt, polyethylene (BPA free), burlap, or other materials and provide excellent drainage, promote root health, and are easy to handle and store.
Those qualities make them ideal for urban gardening, balcony setups, or seasonal plantings. A heavy-duty, high-quality bag can last three to five seasons if cared for properly.
Growing in a bag is much like other forms of raised bed or container gardening with a few exceptions. For success, understanding their usage and soil maintenance is important.
Grow bags are used independently of any other pot or structure. They are made from heavy but breathable materials, allowing for better air circulation and preventing issues like waterlogging, which is common in traditional pots. Unlike rigid-side containers, the fabric promotes “air pruning” —a process where roots reach the edge of the bag, are exposed to air, and die off. The plant responds by creating dispersed lateral roots that can access water and nutrients more easily.
They come in various sizes and can accommodate anything from herbs to large vegetables like tomatoes or peppers. They’re especially useful in areas with poor soil, allowing gardeners to grow plants in a controlled environment. The cost is usually less than hard-sided containers or raised beds.
Choosing the right size
Select a grow bag appropriate for the plant. Small bags (1-3 gallons) work well for herbs and leafy greens, while larger ones (10-20 gallons) are better for root vegetables or larger crops. Master Gardeners have experimented with growing tomatoes and peppers in grow bags and have found 15-20-gallon bags for tomatoes and 10-15-gallon bags for peppers, depending on variety, are adequate.
Preparing the soil
Use a high-quality potting mix with good drainage. A typical mix might include equal parts compost, peat moss or coconut coir, and perlite or vermiculite. Adding fertilizers or amendments, such as compost, can enhance nutrient levels. Fill the bag with the soil mix, leaving about 3-4 inches of space at the top to prevent spills when watering. Make sure the soil is loose to allow proper aeration.
Planting
Verify the soil in the grow bag is well hydrated before planting. Many bagged soils are high in peat and other materials that need a good soaking. Plant seeds according to the seed packet directions and firm the soil gently around the roots of any new plants to provide support.
Water
Grow bags, like other containers, dry out more quickly than a traditional in-ground garden bed. Regular watering is essential, especially in warm weather, but avoid over-watering. A simple drip irrigation system or self-watering tray can help maintain consistent moisture. If unfamiliar with grow bag gardening, it’s essential to monitor the moisture levels closely to appropriately accommodate uptake. Like all gardening, mulching is recommended to conserve moisture.
Refreshing Soil: Replacing all the soil every year can be expensive and is not required, however refreshing the soil is important for maintaining healthy plant growth, especially when reusing grow bags for multiple seasons. For moderately used soil, it can be rejuvenated by mixing the existing soil with additional soil, organic matter, and fertilizer. Plan on replacing about one-third of the volume with new soil every year, mixing it in well.
Clean-up
When not in use, or at the end of the growing season, remove old plants and roots. If needed, discard any diseased plants, and all the contaminated soil to prevent the spread of disease. Wash, rinse, and allow the bags to dry completely before storing in a dry, cool place.
Grow bags are an inexpensive way to grow a home garden. By maintaining best growing practices and refreshing the soil, these versatile containers can provide thriving plants and abundant harvests.
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Master Gardeners are on the radio
Master Gardeners are regular guests on the ’Todd Ortloff Show’ that airs the last Monday of the month starting at 1 p.m. on KNOP (AM 1450 and FM 101.7). See next week’s “Get It Growing” column for information on this month’s topic.
“The Garden Show” presents short garden spots of interest to the community. It airs on KSQM (FM 91.5) on Fridays at 6:40 p.m. and then again (a repeat) on Tuesdays at 11:40 a.m. Coming up on” The Garden Show” on March 21 and 25: “Growing Heirloom Varieties” by Florence Larson.
Plant Clinics
The Master Gardener in-person plant clinics don’t start until May 2025. Until then you can email your questions to mgplantclinic.clallam@gmail.com. Don’t forget to give as many details as you can and send photos. We look forward to helping you answer your gardening questions.
