Tall, upright stems topped with fascinating flower spikes bring a vertical accent to herbaceous borders. Veronicastrum, commonly known as Culver's Root, bushes out with fantastic foliage too, filling a fair-sized gap in the border over time and becoming one of those reliable hardy perennials that you can look forward to reappearing in the garden year after year. Veronicastrum are ideal for a position towards the back of a sunny border where they can eventually grow tall and put on a brilliant show behind lower-growing perennials. They prefer a heavier soil type such as clay or loam, they are not so keen on light, dry sandy soils. Although hardy, resilient and fairly vigorous, these bare roots do require a gentle start to help them settle in.

How to plant:

— Veronicastrum are supplied as bare roots in spring for planting between February and May. They require light and moisture after transit and should be attended to soon after delivery. If you can't plant within 1-2 days of delivery, remove the plants from the packets and place the roots in a dish of water to soak, then plant within a week.

— Veronicastrum should be potted up and grown on prior to planting into borders for best results. This will give them an easier start and then they can be transferred into a border once they are more established. There is a higher risk of failure when bare root perennials are planted directly into borders.

— Soak bare roots in water for 3-6 hours prior to planting. Then, pot each root into a 15-20cm pot with multipurpose compost. Ensure the full root system is submerged in the soil and that the visible buds are level with the soil surface. If supplied later in spring, pale shoots or leaves may already have emerged - these should be left exposed above the soil surface and will green up within a matter of days of planting and being exposed to daylight.

— Water thoroughly after potting and position the plant in a sheltered, sunny part of the garden to grow on. It typically takes between 3-4 months of growing on in a temporary pot for a Veronicastrum be ready to transfer. Once the roots become visible through the drainage holes of the pot, or when the plant easily compose out of the pot with the soil held together by the roots, it is a good time to transfer into a border.

— Veronicastrum prefer to be in a loamy soil which is reliably moist but not boggy or waterlogged.

— When transferring into a border, choose a position in full sun or partial shade with a moist, loamy or clay soil. Water thoroughly after planting and ensure the plant is kept watered regularly during the first growing season while it's settling in. Once established, they do not require such regular watering.

— Veronicastrum are fully hardy and there is no need to protect them from frost over winter.

Aftercare:

— There should be some buds or shoots visible on the bare roots when they are supplied. After planting, the buds or shoots will begin to grow and produce leaves within 1-3 months, depending on when they're planted.

— Whether they flower in the first year usually depends on how early in the season they are planted and also the growing conditions. If they do not flower in the first year, they should start flowering from the second year. They should always produce leaves in the first year, usually by May.

— When the plant finishes flowering, you can deadhead to encourage further blooms. Leave the full length of the stems until autumn when they naturally start to die back, then cut them down at around 5cm from ground level. The plant will become dormant for winter, then regrow again of its own accord the following spring.

— Try combining Veronicastrum with other plants which enjoy heavier soils and a sunny position, such as Thalictrum, Achillea or Liatris.

Read further general instructions about planting bare-root perennials