Verbascum: Indoor Sow or Potted Plant Perennial
How to Sow and Plant
Sowing Seed Indoors:
- Sow indoors 8-12 weeks before last spring frost
- Sow seeds thinly and evenly and just cover lightly with seed starting formula as seeds need light to germinate
- Keep the soil moist at 70-75 degrees F
- Seedlings emerge in 14-25 days
- As soon as seedlings emerge, provide plenty of light on a sunny windowsill or grow seedlings 3-4 inches beneath fluorescent plant lights turned on 16 hours per day, off for 8 hours at night. Raise the lights as the plants grow taller. Incandescent bulbs will not work for this process because they will get too hot. Most plants require a dark period to grow, do not leave lights on for 24 hours.
- Seedlings do not need much fertilizer, feed when they are 3-4 weeks old using a starter solution (half strength of a complete indoor houseplant food) according to manufacturer’s directions.
- If you are growing in small cells, you may need to transplant the seedlings to 3 or 4 inch pots when seedlings have at least 2 pairs of true leaves before transplanting to the garden so they have enough room to develop strong roots
- Before planting in the garden, seedling plants need to be “hardened off”. Accustom young plants to outdoor conditions by moving them to a sheltered place outside for a week. Be sure to protect them from wind and hot sun at first. If frost threatens at night, cover or bring containers indoors, then take them out again in the morning. This hardening off process toughens the plant’s cell structure and reduces transplant shock and scalding.
Planting in the Garden:
- Select a location in full sun in poor to average well-drained soil. Verbascum prefers a slightly alkaline soil.
- Prepare the bed by turning the soil under to a depth of 6-12, inches removing any debris, and lightly raking as level as possible.
- The addition of some organic matter (leaf mold, compost, well-rotted manure) benefits all gardens and is essential in recently constructed neighborhoods. Otherwise verbascum can tolerate poor soils if well-drained.
- Plant on a cloudy day or in late afternoon to reduce transplant shock.
- Dig a hole for each plant large enough to amply accommodate the root ball.
- Unpot the plant and gently loosen the root ball with your hands to encourage good root growth. Verbascum has a tap root so handle carefully.
- Place the top of the root ball even with the level of the surrounding soil. Fill with soil to the top of the root ball. Press soil down firmly with your hand.
- Thoroughly water and apply a light mulch layer on top of the soil (1-2 inches) to conserve water and reduce weeds.
How to Grow
- Keep weeds under control during the growing season. Weeds compete with plants for water, space and nutrients, so control them by either cultivating often or use a mulch to prevent their germination.
- Mulches also help retain soil moisture and maintain even soil temperatures. For perennials, an organic mulch of aged bark or shredded leaves lends a natural look to the bed and will improve the soil as it breaks down in time. Always keep mulches off a plant’s stems to prevent possible rot.
- Careful watering is essential in getting perennials off to a good start. Water thoroughly at least once a week to help new roots grow down deeply. Soil should be damp at about 1 inch below the soil surface. You can check this by sticking your finger in the soil. Water early in the morning to give all leaves enough time to dry.
- Until plants become established, some protection from extreme winds and direct, hot sunlight may be necessary. Good air movement is also important.
- After new growth appears, a light fertilizer may be applied. Keep granular fertilizers away from the plant crown and foliage to avoid burn injury. Use low rates of a slow release fertilizer such as Garden-tone, as higher rates may encourage root rots.
- Plants may need staking.
- Remove spent flower stalks to the basal growth to encourage fresh basal growth.
- Remove and discard foliage after a hard frost in fall.
- In colder regions, apply another layer of mulch (1-2 inches) after the ground freezes in fall. Evergreen boughs (from Christmas trees) provide additional protection. Remove this mulch in the spring.
- May be grown as an annual or biennial. If it is allowed to go to seed it may self sow.
- Wonderful cottage garden perennial, is also great for cutting.
- Attract hummingbirds and beneficial insects.
Common Disease Problems
Bacterial Wilt: This causes yellow streaking on the foliage. It is soil borne and spread by flea beetles. Burpee Recommends: Control flea beetles. Remove infected plants.
Botrytis: This fungus causes a grey mold on flowers, leaves, stems and buds. It thrives in cool wet weather conditions. Burpee Recommends: Remove affected plant parts, avoid watering at night and getting water on the plant when watering. Make sure plants have good air circulation. Contact your Cooperative Extension Service for fungicide recommendations.
Downy Mildew: This fungus causes whitish grey patches on the undersides and eventually both sides of the leaves. Burpee Recommends: Avoid overhead watering. Provide adequate air circulation, do not overcrowd plants. Do not work around plants when they are wet.
Powdery Mildew: This fungus disease occurs on the top of the leaves in humid weather conditions. The leaves appear to have a whitish or greyish surface and may curl. Burpee Recommends: Avoid powdery mildew by providing good air circulation for the plants by good spacing and pruning. Contact your Cooperative Extension Service for fungicide recommendations.
Root Rots: A number of pathogens cause root rots of seedlings as well as mature roots. Burpee Recommends: Pull up and discard infected plants. Make sure your soil has excellent drainage. Contact your Cooperative Extension Service for recommendations.
Common Pest and Cultural Problems
Aphids: Greenish, red, black or peach colored sucking insects that can spread disease as they feed on the undersides of leaves. They leave a sticky residue on foliage that attracts ants. Burpee Recommends: Introduce or attract natural predators into your garden such as lady beetles and wasps who feed on aphids. You can also wash them off with a strong spray, or use an insecticidal soap.
Flea Beetles: These small hopping beetles feed on plant foliage and may spread diseases. Burpee Recommends: Contact your Cooperative Extension Service for insecticide recommendations.
Lygus Bugs (Tarnished Plant Bug): Lygus bugs are ¼ inch long and are green or brown with yellow markings. Nymphs are flightless and smaller than the adults. They suck on stem tips and flower buds and inject a toxic that deforms roots, stems and ruins flowers. Burpee Recommends: Because lygus bugs over winter in garden debris, remove all debris after the first frost. Contact your Cooperative Extension Service for insecticide recommendations.
Slugs: These pests leave large holes in the foliage or eat leaves entirely. They leave a slime trail, feed at night and are mostly a problem in damp weather. Burpee Recommends: Hand pick, at night if possible. You can try attracting the slugs to traps either using cornmeal or beer. For a beer trap, dig a hole in the ground and place a large cup or bowl into the hole; use something that has steep sides so that the slugs can’t crawl back out when they’re finished. Fill the bowl about ¾ of the way full with beer, and let it sit overnight. In the morning, the bowl should be full of drowned slugs that can be dumped out for the birds to eat. For a cornmeal trap, put a tablespoon or two of cornmeal in a jar and put it on its side near the plants. Slugs are attracted to the scent but they cannot digest it and it will kill them. You can also try placing a barrier around your plants of diatomaceous earth or even coffee grounds. They cannot crawl over these.
Spider Mites: These tiny spider-like pests are about the size of a grain of pepper. They may be red, black, brown or yellow. They suck on the plant juices removing chlorophyll and injecting toxins which cause white dots on the foliage. There is often webbing visible on the plant. They cause the foliage to turn yellow and become dry and stippled. They multiply quickly and thrive in dry conditions. Burpee Recommends: Spider mites may be controlled with a forceful spray every other day. Try hot pepper wax or insecticidal soap. Check with your Cooperative Extension Service for miticide recommendations.
Is verbascum deer resistant? Yes, it is deer resistant.
Can I grow verbascum in a container? The plants grow rather large and are not recommended for containers.
Does verbascum attract pollinators? Yes, it attracts bees, hummingbirds and beneficial insects as well.
Do the seeds need a pre-treatment? Will they bloom the first year? The seeds of Southern Charm verbascum do not require a cold treatment and can bloom the first year if started 12 weeks early indoors.
Can I move my verbascum, I don’t like where I planted it. We do not recommend moving established verbascum as it has a tap root which can be easily damaged.