How to Grow Hibiscus in Zone 5
- 1). Situate the hibiscus in a garden bed that has full sun. Incorporate 4 to 6 inches of nutrient-rich compost. If the soil is not well draining, also add 2 inches of sand to increase the texture and improve percolation. Pull weeds and remove any roots, rocks or other debris.
- 2). Chose a hardy hibiscus that suits your garden plan. Rose Mallow is slightly hardier and can handle open sites, while the Althea is a large shrub but requires less care. Rose Mallow is not tolerant to transplanting, so chose a permanent location.
- 3). Provide plenty of water for either type of hibiscus, especially in the hottest part of summer. The plants should have the equivalent of 1 inch of water per week. Rose Mallow needs more water than Althea, but neither should be allowed to dry out. Check the soil before watering, as they do not like soggy roots.
- 4). Spread 2 to 3 inches of mulch around the base of the plant out to the drip line. Leave a 1/2-inch space around the stem to promote air circulation and prevent rotting. The mulch will keep weeds down and conserve moisture. Apply another layer in fall to protect the roots in winter but pull it away from the plant in early spring so new shoots can push through easily.
- 5). Feed the Rose Mallow three times starting in spring. Evenly space the other feedings to culminate by late July. Apply 1 lb. per mature plant or the amount recommended by the manufacturer. The Althea will produce bountiful blooms with just one application of fertilizer in early spring. Water the plants well after fertilizing to prevent root burn, and do not get any on the foliage.
- 6). Stake the most heavily laden limbs. The blooms are large and can actually bow or break the stems. Cut the stems of Rose Mallow to the ground in late fall or early winter. The plant will regrow in spring. Althea will lose its leaves but will not die back. Prune it for shape and to encourage more flowers in early spring.
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