Pro-Mix HP Mycorrhizae Open Top Grow Bag - 1.0 Cu FT

Pro-Mix HP Mycorrhizae Open Top Grow Bag is a ready-to-use, high porosity growing medium for cleaner transplanting and stronger root development in indoor and greenhouse production. Built on the PRO-MIX HP formula, it’s a peat-based, soilless growing medium designed for growers who want good drainage, high air porosity, and lower water retention in a convenient grow bag format.

This open top grow bag is already filled with the growing medium, helping reduce handling and keep work areas cleaner during installation and crop changeovers. Pre-made drain openings and an integrated tear-off opening support a simple, streamlined setup, while the bag’s multi-opening design helps improve aeration in the root zone for more even air distribution. The result is an integrated growing solution that supports healthier root development with less mess and less container handling.

Inside the bag, the HP-style structure is built for watering flexibility and crop seasonality. The combination of fibrous sphagnum peat moss and a high percentage of coarse perlite creates an airy profile that dries out more frequently than general-purpose peat-based mixes. That makes it more difficult to overwater, and it’s well suited for low-light and high-humidity growing conditions where heavier mixes can stay too wet. Because it holds less water, it also supports improved leaching of fertilizer salts during crop cycles, helping keep the root environment more consistent over time.

A key differentiator is the mycorrhizae component. Pro-Mix HP Mycorrhizae includes a beneficial endomycorrhizae that supports plant root systems, enhances nutrient and water uptake, and helps produce more vigorous and healthy plants. For growers focused on strong establishment and steady growth, that root-supporting biology is a meaningful advantage in everyday production, especially during transplanting and early rooting phases.

The core inputs are kept simple and professional: sphagnum peat moss, perlite, calcitic and dolomitic limestone, and a wetting agent, paired with the beneficial endomycorrhizae for root support. This is a good fit for growers looking after annuals, foliage plants, potted flowering plants, greenhouse vegetables, vegetable transplants, and young plant propagation who want a high porosity grow bag that stays airy, drains cleanly, and supports efficient nutrient and water uptake through mycorrhizae.