Hybrid

Potomac Plumblossom

Antirrhinum majus

a bunch of white flowers that are on a tree

Wikimedia Commons

Harvest

110-120d

Days to harvest

📅

Sun

Full sun to partial shade

☀️

Zones

7–10

USDA hardiness

🗺️

Height

0-3 feet

📏

Planting Timeline

Zone:

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Start Indoors

Transplant

Direct Sow

Start Indoors

Transplant

Direct Sow

Showing dates for Potomac Plumblossom in USDA Zone 7

All Zone 7 flower →

Zone Map

Click a state to update dates

Potomac Plumblossom · Zones 7–10

What grows well in Zone 7? →

Growing Details

Difficulty

Easy

SeasonWarm season annual

FlavorFloral and slightly bitter, best used sparingly as a decorative accent.

ColorWhite with plum dust (bicolor)

Zone-by-Zone Planting Calendar

Zone	Indoor Start	Transplant	Direct Sow	Harvest
Zone 3	April – May	June – July	June – August	—
Zone 4	March – April	June – June	June – July	—
Zone 5	March – April	May – June	May – July	—
Zone 6	March – April	May – June	May – July	—
Zone 7	February – March	April – May	April – June	—
Zone 8	February – March	April – May	April – June	—
Zone 9	January – February	March – April	March – May	—
Zone 10	January – January	February – March	February – April	—
Zone 1	May – June	July – August	July – September	—
Zone 2	April – May	June – July	June – August	—
Zone 11	January – January	January – February	January – March	—
Zone 12	January – January	January – February	January – March	—
Zone 13	January – January	January – February	January – March	—

Succession Planting

Potomac Plumblossom doesn't produce all season from a single sowing — you need staggered starts to keep cut-flower stems coming. Start seeds indoors under lights in February, then sow a second round in early March. Transplant the first batch out in April once nighttime temps hold above 40°F, then follow with the March-started seedlings 3-4 weeks later. That gap spreads your bloom window from roughly late June through early fall instead of one compressed flush that's finished by August.

Stop new succession plantings by early June in most zones. Snapdragons drop off sharply once daytime highs are consistently above 85°F — they'll survive, but stem quality goes downhill fast. In zones 9-10, flip the approach entirely: start seeds in September and run Potomac Plumblossom as a cool-season crop for winter and early spring cut flowers.

Complete Growing Guide

White blooms dusted with plum. These bicolor blooms are suitable for field or greenhouse production. Group 3-4: warm season snapdragons bred for optimal performance under long days, high light levels, and warm temperatures. Edible Flowers: The flowers are a colorful garnish for use in salads, desserts, and drinks. The flavor is floral and slightly bitter, so use sparingly. According to Johnny's Selected Seeds, Potomac Plumblossom is 110 - 120 days to maturity, annual, hybrid (f1). Notable features: Easy Choice, Use for Cut Flowers and Bouquets, Greenhouse Performer, Fragrant, Edible Flowers.

Light: Full sun (6 or more hours of direct sunlight a day), Partial Shade (Direct sunlight only part of the day, 2-6 hours). Soil: High Organic Matter. Drainage: Good Drainage. Height: 0 ft. 6 in. - 3 ft. 0 in.. Spread: 0 ft. 6 in. - 0 ft. 10 in.. Spacing: Less than 12 inches. Growth rate: Medium. Maintenance: Medium.

Harvesting

Potomac Plumblossom reaches harvest at 110 - 120 days from sowing per Johnny's Selected Seeds. As an annual, harvest continues until frost ends the season.

A capsule, half hidden by calyx lobes, short-beaked.

Type: Capsule. Length: 1-3 inches.

Storage & Preservation

For fresh storage, keep harvested Potomac Plumblossom blooms in a vase with cool water at 65-72°F in a cool location away from direct sunlight and ethylene-producing fruits. They'll last 5-7 days. For preservation, air-dry blooms by hanging upside-down in a dark, well-ventilated space (10-14 days) for long-term decorative use. Alternatively, press flowers between parchment paper under heavy books for 2-3 weeks to create flat, dried specimens. For edible use, crystallize petals by brushing lightly with egg white and sprinkling superfine sugar, then drying at room temperature for decorative garnishes lasting several weeks when stored in airtight containers.

History & Origin

Potomac Plumblossom is an F1 hybrid developed through controlled cross-pollination. Listed in the Johnny's Selected Seeds catalog.

Origin: Southwestern Europe

Advantages

+Striking white and plum bicolor blooms provide unique visual appeal in arrangements
+Suitable for both field and greenhouse production offers flexible growing options
+Edible flowers add decorative flair to salads, desserts, and cocktails
+Easy difficulty rating makes it accessible for beginner and experienced growers
+Performs well under long days and high light conditions during warm seasons

Considerations

-110-120 day maturity is relatively long compared to other snapdragon varieties
-Floral bitter flavor requires cautious use as edible garnish to avoid overwhelming dishes
-Bicolor pattern may fade or become less distinct in extreme heat stress

Companion Plants

Lavender, catmint, and rosemary are the most practical neighbors for Potomac Plumblossom. All three are low-water plants that won't fight snapdragons for moisture, and their volatile oils — linalool in lavender, nepetalactone in catmint, camphor and borneol in rosemary — genuinely disorient aphids and thrips that zero in on soft-stemmed annuals. Yarrow adds another layer by pulling in predatory wasps and hoverflies that feed on those same pests. That's a real functional combination, not just a pretty one.

Marigolds (particularly Tagetes patula) produce alpha-terthienyl in their roots, which suppresses certain soil nematodes, and their scent helps mask snapdragons from whiteflies. Sweet alyssum planted along the front edge of a bed draws in Aphidius wasps, which parasitize aphids directly. Nasturtium earns its spot differently: it acts as a trap crop, pulling aphids away from your snapdragons. Once a nasturtium plant gets heavily colonized, you can just pull and bag it — you're removing an entire aphid generation in one move.

Black walnut is the companion to take most seriously on the harmful side. Juglone — the compound it releases through roots, leaf litter, and decomposing hulls — stunts or kills many annuals, and its reach through the soil can extend well past the tree's visible canopy. Eucalyptus creates a similar problem through allelopathic compounds in its leaf litter, which acidify and suppress surrounding soil. Don't underestimate either one just because the damage looks like a watering problem at first.

Plant Together

Lavender

Attracts beneficial pollinators and repels pests with aromatic oils

Marigold

Natural pest deterrent, repels nematodes and aphids

Sweet Alyssum

Ground cover that attracts beneficial insects and conserves soil moisture

Catmint

Repels ants, mice, and mosquitoes while attracting pollinators

Chives

Deters aphids and other soft-bodied insects with sulfur compounds

Nasturtium

Acts as trap crop for aphids and adds nitrogen to soil

Rosemary

Repels cabbage moths, carrot flies, and other garden pests

Yarrow

Attracts predatory insects and improves soil health

Keep Apart

Black Walnut

Produces juglone toxin that inhibits growth of sensitive plants

Eucalyptus

Releases allelopathic compounds that suppress nearby plant growth

Sunflower

Allelopathic effects inhibit germination and growth of smaller plants

Troubleshooting Potomac Plumblossom

What you'll see, why it happens, and what to do about it.

Gray, fuzzy coating on buds, stems, or spent flowers — especially after cool, wet weather

Likely Causes

Botrytis cinerea (gray mold) — thrives in humid, stagnant air and colonizes dead or dying tissue first
Spent blooms left on the plant, giving the fungus an entry point

What to Do

1.Deadhead aggressively — don't let spent flowers sit on the plant or pile up at the base
2.Thin any crowded stems to open up airflow; Potomac Plumblossom can get dense by midsummer
3.If it's already spreading, remove affected stems back to clean tissue and dispose in the trash

White powdery coating on upper leaf surfaces, starting mid-to-late season

Likely Causes

Powdery mildew (Erysiphe cichoracearum) — common on snapdragons, especially when nights cool below 60°F while days stay warm
Overhead watering that keeps foliage wet overnight

What to Do

1.Switch to drip irrigation or water at the base in the morning only
2.Apply a diluted neem oil spray (2 tsp per gallon) every 7 days once you spot early signs — it won't cure badly infected leaves, but it slows spread
3.Pull heavily infected plants at end of season and don't compost them

Rust-colored pustules on the undersides of leaves, with yellow halos visible from the top

Likely Causes

Antirrhinum rust (Puccinia antirrhini) — a snapdragon-specific rust fungus, more common in warm, humid climates
Infected transplants or nearby infected ornamentals introduced the spores

What to Do

1.Remove and bag any infected leaves immediately — rust spreads fast via airborne spores
2.Avoid wetting foliage; rust spores need surface moisture to germinate
3.Clear out all plant debris at season's end; Puccinia antirrhini overwinters in dead stem and leaf material

Distorted new growth, sticky residue on leaves, or tiny green or black insects clustered on stem tips

Likely Causes

Aphids (commonly Myzus persicae or Aphis gossypii) — they target soft new growth and reproduce fast in warm weather
Ant activity nearby, which often signals an aphid colony the ants are actively protecting

What to Do

1.Knock them off with a firm stream of water from a hose — do this 2-3 days in a row for small infestations
2.Avoid broad-spectrum insecticides that kill lady beetles and parasitic wasps, which are your best long-term control
3.For heavy infestations, insecticidal soap (1 tbsp per quart of water) applied directly to colonies every 5-7 days works without leaving significant residue

Frequently Asked Questions

How long do Potomac Plumblossom flowers last after cutting?▼

Cut flowers typically last 5-7 days in a vase with fresh, cool water. Keep them away from direct sunlight and ripening fruits, which produce ethylene gas that shortens vase life. Changing the water every 2-3 days and trimming stems at an angle will extend their longevity slightly.

Can I grow Potomac Plumblossom snapdragons in containers?▼

Yes, these snapdragons are well-suited to container growing. Use well-draining potting soil and containers at least 6-8 inches deep. They'll thrive in pots on patios or decks in full sun to partial shade. Container growing may require more frequent watering than in-ground plantings.

Are Potomac Plumblossom flowers edible and safe to eat?▼

Yes, the flowers are edible and suitable as garnishes in salads, desserts, and cocktails. However, they have a floral, slightly bitter flavor—use sparingly. Ensure no pesticides have been applied if you're harvesting for culinary use. Always consume only the petals.

When should I plant Potomac Plumblossom seeds?▼

Start indoors 6-8 weeks before your last spring frost date, or direct sow after the last frost when soil is warm. These warm-season snapdragons prefer temperatures above 60°F. They take 110-120 days from planting to first blooms, so timing your start ensures flowers in mid to late summer.

Is Potomac Plumblossom good for beginners?▼

Absolutely. Potomac Plumblossom is rated as an easy variety, making it ideal for novice gardeners. The bicolor white and plum blooms are reliable, they adapt well to various light conditions (4-6+ hours needed), and they're versatile for both field and container growing with minimal care.

What's the difference between Potomac Plumblossom and other snapdragon varieties?▼

Potomac Plumblossom is a Group 3-4 warm-season hybrid bred for performance under long days, high light, and warm temperatures. Its distinctive white blooms dusted with plum offer ornamental appeal and edible flowers. Many standard varieties prefer cooler conditions, making Potomac Plumblossom better suited for warm climates and extended growing seasons.