Why Are My Lupin Seedlings Dying?

Growing lupins is a delicate but rewarding process. This process involves caring for tender seedlings to mature and produce lovely blooms. But, what would cause lupin seedlings to die?

Your Lupin seeds are dying from adverse environmental conditions, such as heat or humidity. They may also succumb to pests and diseases that attack seeds or seedlings. Planting in waterlogged soil could also result in root rot, which is another cause of seedling death.

Lupins are a stunning addition to your garden with their spires of brightly-colored flowers, and it’s frustrating when your seedlings die off. Read on to discover why lupin seedlings die and how these different factors contribute to lupin death. We will also explore proper lupin seedling care.

Outsidepride Perennial Russells Lupine Wild Flower Mix & Butterflies & Hummingbirds - 500 Seeds

Why Lupin Seedlings Die

Various reasons can be blamed for lupin seedlings dying, so you need to assess them for other signs to narrow down to the particular cause.

As mentioned above, adverse environmental conditions, pests, diseases, and root rot can all cause seedling death. Seedlings are especially susceptible to these factors because their roots, stems, and leaves are not fully formed and therefore do not possess the same resistance as fully grown plants.

Let’s examine these factors and study how they cause death in lupin seedlings.

Adverse Environmental Conditions Causing Seedling Death

Temperature, humidity, and light are environmental factors that significantly affect lupin seedling growth. The main culprits of dying seedlings include the following factors.

  • Extremely high temperatures will increase the rate of evaporation of water in seedlings. When you do not correct this by increasing the water content of the soil, the seedlings will dry out, wilt, and die.
  • Insufficient light. Chlorophyll is a critical component in plant growth due to its role in photosynthesis, which the plants depend on for energy to grow. When seedlings do not get enough light, they do not produce sufficient chlorophyll, so the leaves begin to discolor. Continually depriving seedlings of adequate light will kill them.
  • A humid environment is not suitable for the growth of lupin seedlings. Humidity interferes with the process of transpiration. When this happens, the seedlings cannot take up essential nutrients from the soil. High humidity can also encourage fungal growth in the seedlings. Both of these factors can potentially cause seeding death.
  • The combination of hot climate and low humidity harms seedlings. These conditions accelerate the evaporation rate, causing seedlings to dry out and wilt.

Russell Lupine Mixed Seeds - Colorful Perennial Wildflowers. Fall Planting is Ideal Along with Other Wildflowers.

Pests That Attack Lupin Seedlings

Pests can cause death in lupin seedlings by causing injuries as they feed on the plant or spreading diseases from other infected plants.

Here is a list of pests that attack lupin seedlings and how they cause damage:

  • Lupin Aphids: These pests are gray or whitish and can measure up to 1/16 of an inch (4 mm) long. They attack seedlings by sucking sap from leaves and stems, resulting in wilting and, eventually, death.
  • Lupin root weevils: The larvae of lupin root weevils feed on seedling roots, while the adult insects feed on and destroy the leaves.
  • Snails: These mollusks attack seedlings by sucking on sap and chewing on the leaves, injuring the young plant.
  • Cutworms: These worms damage seedlings by chewing on seedling stems and, in some cases, by cutting them off completely, cutworms can cause seedling death.
  • Thrips: These tiny pests are yellow to gray and measure up to 0.08 inches (2 mm) long. Nymphs and adults attack plant leaflets and tissue and suck sap from the seedlings.

Diseases of Lupin Seedlings

Lupin seedlings can succumb to both fungal and viral diseases. Younger seedlings are most susceptible to these diseases and are therefore less likely to survive when infected.

Here are some of the common diseases that attack lupin seedlings:

  • Anthracnose: A fungal disease that causes necrotic lesions on parts of the seedling, malformed or distorted stems, and leaves. You may also notice orange-colored spores on the affected parts of the young plant.
  • Powdery Mildew: This fungal disease can be observed through white powdery spots on the plant leaves and occasionally brown lesions on the stem.
  • Brown Spot: Characterized by dark brown spots on leaves and stems, this fungal disease is especially harmful to lupins at the seedling stage. The fungus may also attack seedling tap roots.
  • Cucumber Mosaic Virus: Seedlings can be infected when grown from infected seeds or attacked by aphids carrying the virus. Signs of infection include pale and deformed leaves, which may also have faint mosaic patterns.
  • Bean Yellow Mosaic Virus: Signs of infection include necrotic streaks on the shoots, pale leaves that wilt and die, and blackening of the stem.
  • Sclerotinia Stem Rot: A white fungal infection that affects the stem, causing the lupin seedling to wither and die. It is most prevalent in wet regions since fungi thrive in wet conditions.

How the Soil Affects Lupin Seedlings

Soils with poor drainage become waterlogged and can lead to root rot. Waterlogged soils encourage fungal growth and limit seedlings’ ability to take up essential nutrients from the earth. Therefore, growing lupin seedlings in wet soil can result in seedling death.

Caring for Lupin Seedlings

To prevent further seedling death, you need to practice proper seedling care.

Successfully growing lupins begins by selecting the best seeds to propagate. If you already have mature lupin plants, you should harvest seeds or cuttings from the most vigorous and healthy plants. You can also purchase seeds, but do so from a reputable or well-rated brand to prevent disappointment after planting.

Follow these guidelines when caring for lupin seedlings to prevent plant death:

  • Water the lupin seedlings regularly. It would be best if you increase watering during hot weather to keep them from wilting. High temperatures dehydrate the vulnerable seedlings.
  • Maintain well-draining soils to prevent waterlogging, which causes root rot in lupin seedlings. You can achieve this by adding compost to the soil, installing a drainage system, or using the elevation or hilling method to improve soil drainage.
  • Ensure the seedlings get adequate sunlight. Lupin seedlings thrive in full or partial shade, and 6 hours of direct sunlight per day is the recommended exposure for proper growth.
  • Avoid transplanting lupin seedlings as much as possible because of their sensitive tap roots, which may get damaged. If you must transplant, do it between weeks 4 and 6. It would be best if you planted the lupin seeds directly in the garden and let them grow there.
  • Cover the seedlings with mulch to protect them from harmful light, heat rays, and severe cold. You can use shade cloth and row covers to protect your seedlings.
  • Lupin seedlings do best in slightly acidic to neutral soils with a pH of 6.5 – 7. You can correct very acidic soils by mixing them with limestone. You may also restore Very alkaline soils by using Calcium Chloride. You should only add these chemicals after conducting a soil test.
  • Use environmentally friendly snail pellets to keep snails off the lupin seedlings. Consider buying Corry’s Snail and Slug Killer, which is safe for people and pets. It can also be used on fruits and vegetables and contains no restrictions for use around edibles.
  • Treat fungal infections with natural fungicide. Young seedlings are susceptible to damage by regular store-bought fungicide. However, you can mix hydrogen peroxide and water to treat fungal infections. Prepare by adding one teaspoon of hydrogen peroxide to 1 Quart (1 liter) of water.
  • Use neem oil treatment to eliminate seedling pests. Neem oil is a safe, effective, organic pest treatment for seedlings. Bonide’s Neem Oil, available on Amazon, eliminates several pests and comes ready to use. It is also fully organic.

Corry's Slug & Snail Killer, 3.5 lb

Lupins grow best in cooler regions such as Maine and Vermont.

How To Safely Transplant Lupin Seedlings

To protect their sensitive developing tap root system, transplanting lupin seedlings requires expertise and caution. It is better to plant lupin seeds or cuttings in the same place where they will grow to maturity. Doing this mitigates the risks associated with transplanting.

Here are some tips to keep your seedlings safe during the transplanting process:

  • Prepare the garden bed. Loosen up the soil, and add some compost to enrich the soil and improve drainage. Select an area that receives at least 6 hours of full sunlight.
  • Prepare the seedlings. Between 4 and 6 weeks, place the seedling pots outside for about a week to acclimatize them to outdoor environmental conditions. Ensure that you shield the seedlings from the harsh sun and strong wind. Allow them to produce a second set of leaves before replanting.
  • Water the seedlings immediately after transplanting. Water is essential for seedling growth, but too much will damage them. Therefore, whenever you water the seedlings, ensure that the soil does not get too wet or soggy.
Why Are My Lupin Seedlings Dying
Why Are My Lupin Seedlings Dying


Lupin seedlings may die when exposed to adverse environmental conditions, pests and diseases, and root rot caused by being planted in waterlogged soils.

Gardeners should familiarize themselves with signs of pests and diseases in lupin seedlings to ensure timely diagnosis and save their plants. Regular inspection of seedlings will also help you catch any signs of infestation early enough and hopefully save most of your lupin seedlings.

Proper seedling care will also help you prevent the future death of lupin seedlings. When transplanting, take the proper precautions to protect the seedlings.

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