The Japanese garden juniper (Juniperus procumbens “nana”) is perhaps the most iconic bonsai in America -- this diminutive plant is so common in stores, it has earned the nickname “mall bonsai.” No unflattering tag can take away from the plant's quiet beauty, however, which lends a sense of serenity to virtually any space. Dwarf juniper bonsais serve as indoor potted plants and outdoor accents in U.S. Department of Agriculture plant hardiness zones 4 through 9.
Test the dwarf juniper bonsai's soil daily to determine its watering needs. Stick your finger about a half an inch into its soil. If the soil feels dry, water the plant deeply until the soil is thoroughly moist. Never let your juniper bonsai's soil dry out completely, but avoid waterlogging -- maintaining consistently moist soil is key. Mist the tree's foliage with a little room-temperature water daily throughout the spring season.
Apply an organic, slow-release liquid fertilizer with a balanced NPK ratio every two weeks during the dwarf juniper bonsai's growing season or just before, starting around early spring. For this type of fertilizer, about .08 to 0.16 ounces of fertilizer per square foot should do the trick, but always defer to the manufacturer's directions. Avoid fertilizing during the hottest months of the summer and cut applications back to once per month in the fall. Give your bonsai a fertilizer break during the wintertime.
Hand-pinch new buds or needles that grow against the trunk in the early spring season, as new growth appears. Prune only during growing seasons, removing new growth around the trunk and branches by hand. During this time, use hand pruners to remove branches that grow downward from the parent branch, or undesirable, low-growing branches. For a juniper bonsai, your goal is to create a cloud-like foliage shape at the top of the tree.
Shower the tree with lukewarm water and then spray your dwarf juniper bonsai with a mild rotenone pyrethine insecticide if your plant is affected by spider mites, which leave dense webbing in the tree's top foliage and may cause yellowing or a loss of coloration. Follow this routine once per week for three weeks.