Taking Penstemon cuttings is one of the easiest and most reliable ways to propagate these popular, colourful perennials in the UK. Penstemons (also known as beardtongues) are loved for their foxglove-like flowers and long blooming season, but many varieties are not fully hardy in colder regions. Propagating from cuttings gives you free plants, helps maintain favourite varieties, and provides insurance against winter losses. This comprehensive guide covers everything you need to know for successful propagation.
Why Take Penstemon Cuttings?
Here’s why propagating penstemons from cuttings is such a popular and worthwhile technique for UK gardeners:
- Insurance against winter loss: Many penstemons are borderline hardy and can suffer in wet or cold UK winters. Taking cuttings in summer gives you young, vigorous plants that are much more likely to survive the winter than older, woodier specimens, acting as a safety net if your main plants don’t make it through.
- True-to-type plants: Cuttings produce identical clones of the parent plant. This means you can reliably keep the exact flower colour, height, and flowering time of a favourite variety, unlike growing from seed which can produce variable results.
- Cost-effective: Expand your border or fill gaps for free. Instead of buying new plants each year (which can cost £5–£12 each), you can create dozens of new penstemons from just one healthy parent plant, saving significant money over time.
- Rejuvenation: Older, woody plants can be replaced with vigorous young ones. As penstemons age, they often become straggly and produce fewer flowers. Cuttings allow you to replace tired plants with fresh, compact, free-flowering versions every few years.
- Easy for beginners: Penstemons root readily with high success rates (70–90% when done correctly). They are one of the most forgiving perennials for new gardeners to propagate, making them an excellent “starter plant” for learning the art of taking cuttings.
When is the Best Time to Take Penstemon Cuttings?
The best time to take Penstemon cuttings is during the plant’s active growth period, which typically occurs in the spring or early summer.
- Softwood cuttings (easiest & fastest): Late spring to early summer (May–July). New, flexible growth that snaps when bent. Roots in 2–4 weeks.
- Semi-ripe cuttings (most reliable): Mid to late summer (July–September). Firm but still green stems. Excellent success rate and good winter survival.
- Avoid: Late autumn/winter (hardwood is possible but much slower) or peak flowering (energy goes to blooms).
When taking Penstemon cuttings, it’s also important to make sure that the plant is healthy and free of disease. If the plant is struggling or has any signs of disease, it may not be able to handle the stress of having cuttings taken, and the cuttings may be less likely to root successfully.
How to Take Penstemon Cuttings?
The job of taking Penstemon cuttings is not too difficult but there are a few things that you will need to consider in order to ensure the best chance of success. There are also a few things that you will need that you may already have in your shed.
What You Need
- Sharp tool for cutting (knife, secateurs etc.)
- Rooting hormone (Amazon link – opens in a new tab)
- Polythene bag
- Bright windowsill
- Potting mix
- 10-inch pots
- Gloves
Step 1 – Choose the Parent Plant
Select a healthy, vigorous, disease-free penstemon. Look for a plant that is growing strongly with plenty of new shoots. Avoid any plants showing signs of stress (wilting or yellow leaves), powdery mildew (white dusty coating on leaves), or those that are heavily flowering, as flowering stems use a lot of energy and root less successfully.
Step 2 – Select and Cut the Stem
Choose non-flowering side shoots that are 8–12 cm (3–5 inches) long. These should be firm but still flexible.
- Cut just below a leaf node at a 45° angle — this angled cut increases the surface area for roots to form and helps prevent water from sitting on the stem and causing rot.
- Make a straight, clean cut at the top, just above a leaf node. This neat top cut reduces the chance of die-back.
Step 3 – Prepare the Cutting
Remove the lower leaves, leaving only 2–4 healthy leaves at the top. This reduces moisture loss through transpiration while still allowing the cutting to photosynthesise.
Optionally, “wound” the base by gently scraping a thin strip of bark on one side with a knife — this exposes the cambium layer and can encourage faster root formation.
Dip the base of the cutting into rooting hormone powder or gel. While not essential, it significantly improves rooting speed and success, especially for semi-ripe cuttings.
When using rooting hormone, be sure to follow the manufacturer’s instructions for the specific product you are using. It’s important to use the correct amount and apply it to the right area of the cutting to avoid any negative effects.
Step 4 – Plant the Cutting
Fill your pot with moist (not wet) cutting compost. Use a dibber or pencil to make a hole.
Insert the cutting so that at least two leaf nodes are buried in the compost — this gives more opportunity for roots to develop. Gently firm the compost around the stem so it stands upright.
Water lightly to settle the compost and label the pot clearly with the variety and date.
Step 5 – Create Humidity
Cover the pot with a clear polythene bag (with a few small ventilation holes) or place it in a propagator. This creates a humid mini-greenhouse that prevents the cutting from drying out.
Place it in bright, indirect light — a north-facing windowsill or a shaded spot in a greenhouse is perfect. Avoid direct sunlight, which can scorch the leaves. Aim for a steady temperature of 18–22°C.
Step 6 – Aftercare
Keep the compost moist but not soggy — it should feel like a wrung-out sponge. Mist the leaves lightly if they start to wilt.
Check the cuttings weekly for signs of fungal issues (grey mould) and remove any affected ones immediately.
Roots usually begin to form in 2–6 weeks. You can test by giving a very gentle tug — resistance means roots are developing.
Step 7 – Pot On and Harden Off
Once the cuttings have developed a good root system, carefully pot them individually into small pots with good-quality peat-free compost.
Gradually harden them off over 7–14 days by increasing ventilation and exposing them to outdoor conditions. Plant them out in the garden the following spring after the last frost.
When Can I Plant My Penstemon Cuttings Outside?
Early summer cuttings: Often ready by late summer/autumn if well-rooted.
Late summer cuttings: Overwinter in a cold frame or unheated greenhouse, plant out the following spring after last frost (April–May).
Always harden off for 7–14 days before final planting in well-drained soil.
Can Penstemon Cuttings be Propagated in Water?
Yes, you can successfully propagate penstemon cuttings in water, and this method is particularly popular with beginners and children because it’s simple, low-cost, and fascinating to watch.
How to Propagate Penstemon Cuttings in Water (Step-by-Step)
- Take the Cuttings: Follow the same method as compost cuttings — select 8–12 cm non-flowering side shoots and cut just below a leaf node.
- Prepare the Cutting: Remove the lower leaves, leaving 2–4 leaves at the top. You can optionally dip the base in rooting hormone, although it’s not essential for water propagation.
- Place in Water: Put the cuttings in a clean glass jar or vase filled with room-temperature tap water (let tap water stand for a few hours to allow chlorine to evaporate). Make sure the bottom 3–4 cm of the stem is submerged, but the leaves stay well above the water.
- Positioning: Place the jar on a bright windowsill with plenty of indirect light. Avoid direct, strong sunlight as it can cause the water to heat up and turn green with algae.
- Maintenance: Change the water every 2–3 days to keep it fresh and prevent bacterial growth. Rinse the stems gently under running water when you change it.
- Root Development: Roots usually appear within 2–4 weeks. Once the roots are 3–5 cm long (about 1–2 inches), the cuttings are ready to be potted up.
- Potting Up: Gently plant the rooted cuttings into small pots filled with well-draining peat-free compost. Water lightly and keep them in a humid environment (propagator or plastic bag) for the first 1–2 weeks to help them adjust from water to soil.
Pros and Cons of Water Propagation for Penstemons
Advantages:
- Very visual — kids love watching the roots grow.
- No need for compost or pots initially.
- Quick way to check if cuttings are viable.
Disadvantages:
- Less reliable long-term than compost — roots grown in water are often finer and more fragile.
- Higher risk of rot if water isn’t changed regularly.
- Plants can suffer transplant shock when moved from water to soil.
Water propagation is excellent for fun and experimentation, but for more reliable, stronger plants (especially if you’re taking many cuttings), the traditional compost method is usually better. Many gardeners use water propagation as a quick test before committing to compost.
Conclusion
Whether you’re a beginner or an experienced gardener, propagating Penstemon cuttings is a great low-cost way to create new plants. The process is simple and can be done by just about everyone and by following the simple steps above, you can easily create new plants that will thrive in your garden.
Garden Doctor Tips
“If you can, take multiple cuttings from multiple plants to increase chances of success!”
“If you want to involve the kids, pop your cuttings in water so you can see the roots as they grow!”
“Remember not to leave the cutting in direct sunlight as this can cause the leaves to burn and the cutting will be unlikely to survive!”
“When covering, ensure that your cuttings are not touching the plastic. Being in contact with the plastic when wet can lead to rotting and other problems!”
Frequently Asked Questions
What potting mix do I need for Penstemon cuttings?
Like with many plants, Penstemon cuttings do best in a slightly acidic potting mix (6.0 to 6.5 pH). You can make your own potting mix or purchase a pre-made mix from a garden centre.
Can Penstemons be grown from cuttings?
Yes, Penstemons can be grown from cuttings. Cuttings should be taken from healthy, young plants in late spring or early summer.
Can you take cuttings from Penstemons?
Yes, you can take cuttings from Penstemons. This variety of flowers is very easy to propagate from cuttings, and in fact, taking cuttings is my favourite way to create new plants.
When should you take penstemon cuttings?
The best time to take Penstemon cuttings is in late spring to early summer when the plant is in its active growth phase.
How long do penstemon cuttings take to root?
Penstemon cuttings can take between 2 to 6 weeks to root, depending on the environmental conditions and the health of the cutting.
Where do penstemon cuttings go overwinter?
Penstemon cuttings taken later in the season should be kept indoors in a cool, dark place over winter until they can be planted outside the following spring.
How do I take a cutting from a penstemon plant?
To take a cutting from a Penstemon plant, choose a healthy stem and cut it to about 6-8 inches in length. Remove the lower leaves, leaving only 2-3 pairs of healthy leaves. Dip the cut end into rooting hormone powder and plant it in a potting medium.
Can I take penstemon cuttings in September?
You can take Penstemon cuttings in September, but it’s best to do it earlier in the season to give the plant a chance to establish roots before winter arrives.
What do you do with penstemon in the winter?
In colder climates, Penstemon plants should be cut back in the fall and covered with a thick layer of mulch to protect them from freezing temperatures. Alternatively, they can be dug up and overwintered indoors in a cool, dark place.
Author
Trevor Wright is not just a seasoned horticulturist; he’s the esteemed Garden Doctor. With a BSc in Horticulture and years of hands-on experience in the soil, Trevor has become a trusted mentor for all things gardening. As the founder of Garden Doctor, he’s committed to clarifying the intricacies of gardening, offering straightforward advice that’s rooted in years of practice. His writing is a garden of how-tos, savvy insights, and comprehensive guides that enable individuals to nurture and grow their garden dreams. When he’s not knee-deep in garden beds, Trevor is at his keyboard passing on his green-thumbed wisdom to budding gardeners, ensuring that the legacy of sustainable and joyful gardening blossoms far and wide.
