Smooth False Foxglove

Year-round

Smooth yellow false foxglove is a native perennial wildflower that taps into a nearby oak tree's roots for some of its nutrients, so it does best in a partly shaded spot within reach of an established oak rather than out in an open bed.

• Give it partial shade and well drained soil on the dry to medium-dry side, ideally within reach of an oak tree's root zone.
• It grows four to seven feet tall with spikes of tubular yellow flowers from July into September that bring in bumblebees and hummingbirds.
• This plant is a root hemiparasite. It draws some water and nutrients from a host oak through underground connections but keeps its own green leaves and makes its own food too, and it does not harm the tree.
• It is native to New York, including several counties in the New York City area, so it fits naturally into a shaded or part-shade native planting near mature trees.

Fall

By fall the flowers finish and turn into small seed capsules, and the foliage starts to yellow and die back with the season's first cool nights.

• Seed capsules can be left in place. This plant self-sows readily near an oak's root zone and often forms a small colony over a few years.
• If you want to collect seed for a new spot, gather capsules once they turn brown and dry, then sow right away in fall near another established oak rather than storing seed for spring.
• Top growth dies back completely with frost. That is normal for this species and it will return from the root the following spring.

Winter

This plant is fully dormant in winter, with dead top growth above ground and its root system still connected to a host oak underground.

• No watering or feeding needed while it is dormant.
• Leave the root zone undisturbed. Do not dig, till, or pile heavy mulch right over the crown since that can disrupt the underground connection to the nearby oak.
• Seed capsules left standing over winter can still drop seed and feed birds, so it is fine to leave old stalks up until late winter rather than cutting them right after frost.

Cut old dead stalks down to the ground in late winter, before new spring growth starts, for a tidy front-bed look.

Spring

In spring new stems push up from the perennial rootstock, and this is the season to plan any new plantings so a young plant can link up with a nearby oak's roots from the start.

• New top growth often shows up later than many spring perennials, sometimes not until the soil has warmed well into the season, so do not assume a plant died over winter if you do not see it right away.
• If you are adding new plants, sow seed in fall close to an established oak rather than setting out a potted plant in spring. It establishes far better with direct contact to host roots from the start.
• Avoid digging or tilling near the base of the nearby oak this time of year. Disturbing those roots can break the underground connection this plant depends on.

Summer

Summer is bloom season, from July into September, when tall spikes of yellow flowers open and pull in bumblebees and hummingbirds looking for nectar.

• Keep soil on the dry to medium-dry side. This plant relies partly on nutrients it pulls from its host oak, so it does not want constant watering or a spot that stays soggy.
• Skip the fertilizer. Extra feeding does not help a hemiparasitic plant that is already drawing nutrients underground, and it can encourage weak, floppy growth.
• Plants can reach four to seven feet and may lean in a rich, part-shade bed. A discreet stake or placing it toward the back of a front-yard planting keeps the display tidy.

Stake tall stems or set the plant toward the back of the bed so it does not flop forward over a front walk or lawn edge.