Red spinach (Amaranthus tricolor L) is a horticultural vegetable that contains anthocyanins, protein, calcium, phosphorous, iron, vitamin A, vitamin C, and B vitamin. However, this plant has not become a major commodity, so it is generally grown in lands with a low level of soil fertility. Application of arbuscular mycorrhizal (AM) fungi in powder dosage form can help plant growth with a positive effect. However, this dosage form has several weaknesses, so a study aimed at knowing the effectiveness of AM fungi in different dosage forms is needed in physiological studies to analyze plant growth and the level of colonization of red spinach roots in the vegetative stage. This research was carried out using the model of the Latin square design (LSD) with three treatments for AM dosage forms of fungi: tablets, sachets, and powders, and without mycorrhizal application (control). The results showed that AM fungi in sachet dosage form could colonize the roots of spinach plants with the highest percentage, although physiological studies have not given consistent results. The sachet dosage form of AM fungi is the novelty of this study. AM fungi in a sachet dosage form can are recommended as the dosage form the most attractive, efficient, and effective to be applied and mobilized to farmers' fields.