Hill's Thistle

Hill's Thistle should be watered deeply but infrequently. Water thoroughly when the soil is dry to the touch (2-3 inches) and then wait until it is nearly dry before watering again. In the hottest, driest times, Hill's Thistle may need to be watered weekly, while during cooler and wetter times, this species may need to be watered less, as infrequently as every 2 weeks. The depth of the soil should never be allowed to dry completely, however.

Hill's Thistle (Cirsium pumilum var. hillii) grows best when exposed to full sun, which typically includes 6-8 hours of continuous daily sunlight. However, this plant species is also able to tolerate some shade, especially during the hottest parts of the growing season. Even if it is exposed to partial sun for most of the day, it still needs some direct sunlight in order to thrive. During the cooler months, Hill's Thistle can benefit from a little more shade, as this helps keep the soil moist and prevents the plant from suffering from dehydration.

Hill’s Thistle should be pruned when the main flowering season has ended – usually by mid-summer. It is important to only prune off dead or dried up stems and flower heads, as doing so will allow new and healthy growth to come through. The amount of pruning required should not be excessive. The plant itself has a naturally low-growing habit and should not be given more than a light shaping. Minimalistic pruning approaches are usually best for this species, as it encourages a bushier and denser growth habit. To achieve this, simply remove a few of the lower stems and flower heads, taking care to leave most of the foliage intact. Doing so will help to open up the center of the plant, allowing new growth from the upper branches to shine.