Growing rose hips is as much about what you do as what you do not do when caring for your rose bush, tree, vines or shrub. Rose hips are the mature fruit that develops from the base of a spent rose flower. After a rose blooms and the petals drop away the bulbous green base below the sepals will swell to a round shape and deepen in color to an orange or red hue. This rose hip is basically the plant ovary that contains the DNA via seeds and will ripen and mature on the rose plant well into winter. Rose hips are eaten by birds and insects, harvested for use by humans and in the wild often rot and drop their seeds onto the soil. They key to growing rose hips is to never harvest or deadhead the flowers on the rose but leave them in place for the hips to develop. Good cultivation practices of abundant water, nutrient-rich soil and regular fertilizing also add to the abundance and health of hips that develop.
Water your roses regularly and deeply so that the soil is kept evenly moist at all times throughout the growing season. Do not water so frequently that the roots sit in soggy soil, but never let the soil dry out entirely either. Once a week deep watering around the root ball is usually sufficient in all but the warmest and driest climes.
Feed your roses with an organic rose food once a month or several times a season if using a slow-release formulation. Use rose tone, fish emulsion or some other fertilizer according to label dosing recommendations.
Amend the surface soil and mulch with several pounds of high-quality compost each year to enrich the soil. Scratch the compost into the top inch or so of soil with a cultivating fork. Mulching with compost will also hold moisture to the soil and keep weeds from cropping up.
Refrain from harvesting rose flowers or deadheading spent blooms, instead allowing the petals to drop off the flower and the rose hip to develop. Harvest rose hips with clean sharp secateurs when they are mature and ripe (when the color is deep and the hip gives slightly to the press of your thumb). Cut the bunches of hips off on the stem that emanates from the main cane or branch.