Native plants like Thimbleberries tend to do fine with neglect, however there are some things to take into consideration. When first planting your thimbleberry plants, you shouldn't let the ground completely dry out during the first season. Occasional deep waterings, especially during the hottest part of summer will be necessary until the plants are established. This usually takes one season. However, the soil shouldn't be kept soggy - thimbleberries are not marsh plants. They will do better with well-drained soil.
Though thimbleberry plants will grow well without additional watering once established, they will grow much larger, thicker, and more leafy if they are watered regularly. The plants do best in partial sun, and may require supplemental watering if they get full sun all day long. Fertilizing isn't necessary unless your soil is uncommonly poor. But you can get more luxuriant plants if you occasionally fertilize them. We recommend half-strength Miracle-Gro applied two or three times per year if you want to fertilize them.
Thimbleberries grow from thin canes. When green, these canes will only support plants up to about 3' tall. Any taller than that and the canes will tend to fall over. However, canes that overwinter tend to be stiff and provide support for green canes. In fact, with the support canes, the green canes can grow as tall as 6'. When the bushes go dormant, the leaves will drop and the canes will turn brown. As many as half of these canes will not sprout growth in the next spring. But it isn't possible to determine which ones will and which will not. Some may find these dry brown canes to look unsightly and want to prune them down when they go dormant. This, however, will force the roots to send up new canes in the spring which will not grow as tall and will tend to fall over in the wind if they reach about 3'. A large, healthy patch of thimbleberries will be one whose canes are left alone over the winter. Some of the dead canes will naturally fall over. These can be removed since they provide no benefit for the remaining canes.
Thimbleberry spreads primarily by shallow roots. They do not tend to invade lawns, but they may spread in flower beds that are sparsely occupied. However, they are easy to control. Because the roots of the canes are all interconnected, do not ever use an herbicide when unwanted canes pop up. Rather, use a spade or fork to loosen the soil around the unwanted cane, then grasp them near the base and slowly pull straight up. This will start pulling up the roots so you can see what direction they are headed from. You can pull the root up all the way back to where you want the thimbleberries to remain, then cut the root at the ground and throw the undesired cane in your compost. Be sure to push the end of the remaining root back into the soil and cover it with dirt. The plants are vigorous and you can chop the roots with a sharp spade rather than pruning shears if you wish. If canes come up on the other side of a fence, you may wish to use a spade to sever the roots (making your best guess as to where that may be), so that if the neighbor uses herbicide, it won't affect your plants.
You may find that there are galls (swellings) on some of your canes. These are caused by insects. They may look unsightly, but they tend not to harm the plants. Insects lay eggs inside the galls which hatch in the spring. If you decide to cut the galls off, you need to burn them, otherwise the insects will simply hatch out of the galls where you threw them into the compost. But chances are, the insects that cause the galls are coming from somewhere else anyway, so the best you can hope for is simply reduce the number of galls. We don't recommend insecticide unless something is ravaging the leaves and/or stems.