Colourful and refreshing Lupin plants are almost everyone’s favourite and, of course, bumblebees love them. This plant grows at its best under full sunlight, but they are known to grow in partial shade. Overall, the Lupin plants have a relatively short lifespan and will only flower for around 5-6 years before becoming unproductive after which, the taproot will need dividing to provide another 5 flowering years. Lupin flowers bloom at their maximum from May to June and start fading quite soon after. Once the plant has died completely, it cannot regrow on its own. This is why you need to prune and cut it back so that it may regrow and live further. But do you know when to cut back Lupins? Do you cut back Lupins in autumn? 

Butterfly on Blue Lupins
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Understanding the Life Cycle of Lupins

Before diving into what to do with lupins after flowering, it’s essential to grasp the life cycle of lupins. These perennial plants go through several stages, from germination to flowering and then back to a dormant phase.

  • Germination: This is the initial stage where the lupin seeds begin to sprout. After planting, with the right conditions of moisture and temperature, the seed breaks open, sending out a tiny root and shoot. This process usually takes 7-10 days.
  • Seedling Growth: Once germinated, the lupin enters the seedling phase. Here, the first true leaves appear, and the plant starts to establish its root system. Proper care during this stage, including ensuring adequate moisture and protection from extreme conditions, is crucial.
  • Vegetative Growth: As the lupin grows, it enters the vegetative stage. Here, the plant focuses on producing a robust system of leaves and stems. This phase is vital for photosynthesis, allowing the lupin to gather energy for the upcoming flowering stage.
  • Flowering: This is the stage most gardeners eagerly await. Depending on the variety, lupins will begin to flower in late spring to early summer. The plant produces its iconic tall spires filled with colourful flowers. This phase can last several weeks, with the plant producing multiple flower spikes.
  • Post-Flowering: After the blooms fade, lupins enter the post-flowering phase. The plant starts to produce seed pods, which, if left unchecked, will mature and release seeds for the next generation.
  • Dormancy: As colder months approach, lupins prepare for dormancy. The above-ground parts of the plant may die back, but the roots remain alive, storing energy for the next growing season. During this phase, the plant is in a state of rest and conserves energy.
  • Regrowth: With the arrival of warmer temperatures and longer daylight hours, lupins break dormancy. Drawing energy from the stored reserves in their roots, they begin a new cycle of growth, leading once again to the flowering stage.
Vibrant Pink and Purple Lupins
Vibrant Pink and Purple Lupins

Do Lupins Need Deadheading?

Unless you want your lupins to use their energy in producing seeds, it is vital to deadhead lupins after the blooms are spent. The benefits of deadheading are:

  • Prolonged Blooming Period: Deadheading encourages lupins to produce more flowers. By removing spent blooms, you signal the plant to redirect its energy to producing new flowers rather than seeds.
  • Energy Conservation: Flower production is energy-intensive. By removing faded flowers, the plant can conserve energy, which can then be used for root and foliage growth.
  • Prevention of Unwanted Seedlings: Lupins can self-seed. By deadheading, you can control where and when new lupin plants grow, ensuring your garden remains as you’ve designed it.

When to Cut Back Lupins?

Deadheading should be done as blooms fade to encourage a second flush of flowers and prevent the plant from putting energy into seed production. Once the foliage has wilted and died in the autumn, it can be cut back to keep the plant tidy and prepare it for the next growing season.

Below are the 4 times that you will need to cut back lupins:

  • Deadheading: Begin by removing the spent flower spikes. This process, known as deadheading, encourages the plant to produce a second, albeit smaller, flush of blooms in late summer.
  • Cutting Back Foliage: If the foliage shows signs of yellowing or disease, trim it back to the base. Healthy green leaves can be left as they continue to photosynthesize and provide energy for the plant.
  • Removing Seed Pods: If you don’t wish for your lupins to self-seed, ensure you remove any developing seed pods. This also helps conserve the plant’s energy.
  • Winter Preparation: In the autumn as the plant begins to die back, you can cut the entire plant down to just above ground level. This helps protect the plant from fungal diseases and prepares it for winter dormancy.

Note: Always ensure your pruning tools are clean and sharp. This not only makes the task easier but also prevents the spread of diseases.

Windswept Twisted Lupin
Windswept Twisted Lupin

What to Do With Lupins After Flowering?

Lupins should be deadheaded as soon as the blooms fade. The entire foliage should be cut back once it has wilted and died. Here’s a step-by-step guide on how to cut back lupins after flowering:

What You Need

  • Sharp secateurs (Amazon link – opens in a new tab) or scissors.
  • Gardening gloves to protect your hands.

Step 1: Timing is Key

Before you begin the pruning process, observe your Lupin plant. Ensure that approximately 70% of its flowers have faded. Deadheading or pruning while a significant number of flowers are still in bloom can hinder the plant’s growth and potential for future blooms.

Step 2: Focus on the Primary Stem

With your pruning shears, target the primary stem of the Lupin. Carefully cut the stem just above the first side stem. While the primary stem won’t regenerate, the side stem will continue its growth, potentially producing flowers later in the season.

Step 3: Repeat the Process

As you inspect the Lupin, you’ll likely find multiple stems with faded flowers. For each of these stems, repeat the cutting process mentioned in Step 2. This ensures that all parts of the plant have the opportunity to regrow and bloom.

Step 4: Addressing the Entire Plant

After all individual faded flowers have been addressed, turn your attention to the overall plant. Once all the flowers on the Lupin have faded, it’s time to cut back the entire plant. Focus on cutting it back to the newest basal leaves. This step encourages new growth and ensures the plant remains vibrant and healthy.

Step 5: Monitor for Reblooming

Lupins have the potential to bloom again after the initial flowering phase. If you notice new blooms after your initial pruning, simply repeat the steps mentioned above. This ensures that your Lupin remains healthy and continues its growth cycle.

Close up of Lupin Flower Head
Close up of Lupin Flower Head

Problems with Lupins After Flowering

Lupins, while hardy, can sometimes face challenges, especially after their flowering phase. Here’s how to address some common concerns:

Dealing with Pests and Diseases After Flowering

  • Pests: Aphids and slugs are common pests for lupins. Regularly inspect your plants and consider natural remedies or insecticidal soaps to combat these pests.
  • Diseases: Mildew and rust can affect lupins. Ensure proper spacing between plants for adequate air circulation and consider fungicidal treatments if necessary.

Ensuring Soil Health and Adequate Watering

  • Soil: Lupins prefer well-draining soil with a slightly acidic to neutral pH. After flowering, consider a light application of a balanced fertilizer to replenish nutrients.
  • Watering: While lupins are drought-tolerant once established, they benefit from deep watering, especially during dry spells. Ensure the soil remains moist but not waterlogged.

Tips for Maintaining Vibrant Lupin Foliage

  • Mulching: Apply a layer of organic mulch around the base of the plant to retain moisture and suppress weeds.
  • Pruning: Regularly remove dead or yellowing leaves to encourage new growth and improve air circulation.
Beautiful Pink Lupins in Bloom
Beautiful Pink Lupins in Bloom

Lupin Propagation After Flowering

Lupins can be propagated through seeds, cuttings, or division. Each method has its advantages and specific steps to follow.

How to Collect Seeds from Lupins After Flowering

  • After the flowering phase, lupins produce seed pods. Once these pods turn brown and dry, they’re ready for harvesting.
  • Carefully snip off the pods and place them in a paper bag. Allow them to dry for a few more days.
  • Once dry, break open the pods to collect the seeds. Store them in a cool, dry place until you’re ready to plant.

Tips for Successful Germination and Growth

  • Pre-treatment: Lupin seeds benefit from a process called scarification. Gently rub the seeds with sandpaper or nick them with a knife to improve germination rates.
  • Planting: Sow the seeds in well-draining soil, about 1/4 inch deep. Water regularly until seedlings emerge.
  • Transplanting: Once seedlings have grown a few inches tall and have at least two sets of true leaves, they can be transplanted to their final location in the garden.
Blue Lupin Flower Spikes
Blue Lupin Flower Spikes

Preparing Lupins for the Next Season

Ensuring that your lupins return with a flourish in the subsequent season requires some foresight and care. Here’s how to prepare your lupins for their next growth cycle:

Importance of Soil Nutrition and Fertilization

  • Soil Nutrition: Lupins thrive in well-draining soil that’s rich in organic matter. Consider enriching your soil with compost or well-rotted manure to boost its nutrient content.
  • Fertilization: While lupins are not heavy feeders, a light application of a balanced fertilizer in early spring can provide them with the necessary nutrients for robust growth and flowering.

Winter Care for Lupins

  • Mulching: As winter approaches, apply a thick layer of organic mulch around the base of the plant. This helps protect the roots from freezing temperatures and retains soil moisture.
  • Protection: In regions with harsh winters, consider covering lupins with a frost cloth or burlap to shield them from extreme cold and wind.

Ensuring Robust Growth in the Next Blooming Season

  • Pruning: In early spring, as new growth emerges, prune away any dead or damaged stems from the previous year.
  • Watering: Ensure consistent watering, especially during dry spells in spring, to support the plant’s growth and flowering.
New Lupin Growth
New Lupin Growth

Common Myths About Lupins

Myth: Lupins need a lot of water to thrive.
Fact: While lupins appreciate consistent moisture, they are relatively drought-tolerant once established.

Myth: Lupins only bloom once in a season.
Fact: With proper care, including timely deadheading, lupins can produce a second, albeit smaller, flush of blooms in late summer.

Conclusion

“Do you cut back Lupins in autumn?” Well, yes once the plant has died back in the autumn, lupins should be cut back to the base to prepare the plant for the winter and new growth in the spring. With the proper cutting techniques, you can keep the plant blooming better for longer. Fully bloomed Lupins can add a lot to the beauty of a place. Hence, with all this effort, you are doing your garden a favour that you would yourself enjoy.

Tips for Cutting Back Lupins Infographic
Tips for Cutting Back Lupins Infographic

Garden Doctor Tips

“Cut Lupins all the way back to the base in the autumn when all of the flowers have faded, and the plant has withered and died!”

“As with all pruning, ensure that your blades are clean and sharp, and your cuts are true!”

“Do not deadhead the last flowers of the season if you want to harvest the seeds however, lupins do not grow true to type from seed!”

“To extend the life of your lupins, separate after 5 or 6 years when the plant has become woody and unproductive!”

Frequently Asked Questions

Should lupins be cut down after flowering?

Lupins should be deadheaded after flowering to enable fresh growth and prevent the plant from producing lots of seeds.

At the end of the summer, lupins can be cut back to prepare them for winter.

Do lupines come back every year?

Lupines will flower for approximately 5 years before the plant becomes woody and unproductive. To extend the life of your lupins, divide the taproot after 5 years and re-plant.

What do you do with lupins after flowering UK?

After flowering, lupins can be deadheaded to enable growth on the flowering side shoots. Once all flowers have faded and the plant dies off in the autumn, the plant can be cut back to the base.

When can I cut back my lupins?

It is best to cut back lupins once the flowers have begun to fade. When at least 70% of the flowers have faded, cut back to just above the highest side-shoot which will then begin to flower therefore extending the flowering period.

Are lupins poisonous to cats?

Yes, Lupins are mildly toxic to cats, but not usually deadly.

Symptoms of poisoning include vomiting, tremors or convulsions, swelling of the throat that can lead to suffocation, elevated heart rate and fever. Pets can experience kidney damage if they ingest toxic levels of lupins although it is rare for a cat to eat enough to cause this problem.


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.


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