Foxglove tree: planting, care & our favourite varieties

Foxglove trees are breathtakingly beautiful, but is it worth having one in your garden? Discover the wonderful flowering Paulownia tomentosa and learn all about care, propagation and more.

Foxglove trees (Paulownia tomentosa), also known as princess trees or empress trees, are nothing less than sensational. They love warm climates and are rarely affected by drought. Read on to find out all about these stunning trees as well as how to plant, care for and prune them.

Foxglove tree: flowering time, origin and characteristics

A foxglove tree’s violet blooms are truly a gift to behold. These deciduous hardwood trees belong to the Paulowniaceae family and are native to China and Taiwan. Planted as a single tree, a Paulownia tomentosa can reach up to 15m tall, and they have strikingly thick and stiff, grey-felted shoots. They bloom between April and May, during which time their entire crown is covered with 20cm-long flower panicles. The panicles typically bear up to 30 individual flowers, which are each 3 to 12cm long. After foxglove trees bloom, their massive green leaves emerge, providing ample shade throughout summer.

As foxglove trees originate from warm regions, they readily adapt to hot urban climates and tolerate prolonged periods of heat and drought. This is just one of the reasons they are good trees for climate change. Not only are these trees better adapted to climate change than many native woody species, but their rapid growth and massive green leaves make them terrific CO₂ guzzlers. Unfortunately, in areas with cold winters, the flower buds can freeze and, subsequently, the blooms will fail to appear.

Paulownia varieties

The Paulownias available for purchase typically differ by frost sensitivity. The most well-known include:

• Wild bluebell tree (Paulownia tomentosa): when mature, these trees can generally tolerate low temperatures, but young plants need protection from frost. Wild bluebell trees grow quickly when young and often look picturesque when old.
• Bluebell tree hybrid (Paulownia tomentosa ‘NordMax21®’): this variety was bred specifically for European climates and can tolerate temperatures down to -22 °C. This variety grows upright and fast.

There are other foxglove tree varieties besides the two mentioned above, but they are ill-suited to the home garden and mainly cultivated for their high-quality wood.

Planting foxglove trees

Foxglove trees are sold in a variety of forms. From cuttings and saplings to perennials in pots, there is a suitable form for every need.

Location: foxglove trees prefer sunny locations with well-drained soil. The soil’s pH range should be about 6.5 to 7.5. If the soil is too acidic, add some garden lime to lower the pH. If the soil in your garden is dense or clayey, work some sand into it to avoid waterlogging or long periods of moisture. For especially sandy soils, we recommend working some compost or potting soil into the substrate. Our Plantura Organic All Purpose Compost has a pH value of between 6.1 and 6.9. It is ideal for planting foxglove trees and many other woody plants and perennials. Make sure the soil is not too moist or rich in nutrients. This can cause the wood to grow too plump and can make it susceptible to frost.

Instructions for planting foxglove trees:

• When: plant young trees after the last frost. Plant perennial root balls in March.
• Planting distance: for picturesque and healthy growth, keep a 4m planting distance.
• Planting hole: dig a hole 1.5 times the size of the root ball.
• Soil: mix soil in the planting hole with sand or mature compost as needed.
• Procedure: place the foxglove tree in the planting hole. Keep the root neck just above the soil surface. Press the soil down firmly. Use excess soil to form a watering rim, and water generously.

As the trees’ crowns and roots grow vigorously, keeping foxglove trees in pots permanently is not an option. Foxglove trees only tolerate growing in pots for the first few years.

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Tip: Deer and hares love to browse on Paulownia trees. In gardens where these animals are common visitors, it may be wise to install browsing protection for young trees. The non-toxic foliage can also be used as animal feed for livestock.

Foxglove tree care

Despite the nickname “princess tree”, this perennial is easy to care for. Keep reading to learn about the most important care measures.

Watering and fertilising

After planting, water your young foxglove tree regularly. Once it has established itself, it will need less water, and, in fact, copes well with drought. As a rule, foxglove trees do not need to be fertilised. If the soil is extremely poor, fertilise before June. However, feed sparingly, as too much fertiliser, especially nitrogen, can make branches more susceptible to frost damage in winter.

Pruning foxglove trees

Foxglove trees naturally form a main trunk that, depending on the species, grows more or less straight. Generally, pruning is not necessary. However, if your tree has frost damage, remove the dead shoots.

Some gardeners like to prune their foxglove tree to increase the height of the trunk. To do this, regularly remove the young side shoots until the desired crown height is reached. Omit pruning altogether to encourage a more densely branched, pyramidal tree. To avoid unwittingly removing flower buds, wait until after your foxglove tree has flowered to prune.

Propagation

Foxglove trees can be propagated via cuttings, root cuttings or by seed. Propagating with foxglove tree cuttings is popular, as the resulting trees tend to grow faster and better. Take foxglove tree cuttings in autumn. Start by finding a 20 to 30cm-long young shoot and make a diagonal cut at the base of the shoot. Next, place the cutting in a growing medium so that only the top two buds are sticking out. Opt for a loose, nutrient-poor soil, as this will help the cutting to root well. Our Plantura Organic Herb & Seedling Compost is ideal for this, as it contains the ideal nutrient content as well as perlite to loosen it up. Once the cutting is in the soil, water it generously. During the winter, move the young plants to a frost-free place. However, living spaces are not suitable, as they are too warm and the air is too dry.

Are foxglove trees hardy?

Most foxglove tree species are hardy when fully grown. In warmer regions and sheltered locations, you can expect little to no frost damage. However, if you live somewhere cold, overwinter your potted foxglove trees in a frost-free but cool place.

Are foxglove trees poisonous?

Paulownia tomentosa fruits are slightly poisonous, so are not edible. Although they resemble hazelnuts, small children and pets do not tend to be drawn to the fruits, so there is usually no need to worry. Foxglove tree leaves, on the other hand, are not poisonous. In fact, they are even part of the cuisine in some Asian countries.

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Magnolias are also famous for their lush flowers. Learn how to care for, prune and propagate flowering magnolias in our dedicated article.