Ornamental · Boraginaceae
Lacy Phacelia
Phacelia tanacetifolia
Sow it once and watch the bees pour in, a haze of lavender-blue buzzing hard all summer.
Full sun
Every 5–10 days
42–56 days
USDA 3–10
Overview
Lacy phacelia is a fast, good-natured annual out of California and the western states, named for its fine, fern-like leaves and the coiled sprays of lavender-blue bells that unspool like a fiddlehead. It rides in the borage family, not the daisies, even though the tansy-like foliage fools loads of gardeners. Few plants this easy to grow hit this far above their weight.
The headline act is the way it pulls bees in. Honey bees, native bees, hoverflies, and parasitic wasps swarm the flowers, which is exactly why it powers cover-crop and pollinator mixes far more than tidy borders. Gardeners also run it as a green manure, since it scavenges loose soil nitrogen and chokes out weeds as it grows.
Treat it as a sprinter of an annual that flowers a few weeks after sowing and burns through a single season. Sow in spring or fall, hand it sun and soil that drains, and stagger a few sowings to keep the bloom rolling. Let it run to seed, though, and it bounces right back uninvited the next year.
Care
The short version: hand phacelia full sun and well-drained soil, water only until it settles in and then back off, sow in succession for a long bloom, and cut it back before it seeds.
Light
Hand phacelia full sun and it flowers hardest and pulls the biggest crowd of bees. It will take partial sun or light shade, but flowering thins out in shade and the plants stretch up and flop.
Water
Water young seedlings until they grab hold, then back right off, because phacelia turns drought tolerant once established and cruises on 7 to 18 inches of rain or watering a year. Let the top half of the soil dry between drinks, and never let it stew in wet ground.
Soil
It powers ahead in well-drained sandy, gravelly, or loamy soil and laughs off the poor, dry ground that flattens fussier plants. The pH range runs wide, anywhere from 6.4 to 8.5, so most garden soil suits it fine as long as it drains.
Temperature
Phacelia takes a big swing, from about 18°F to 95°F (-8°C to 35°C), and young plants shrug off a light frost. A hard freeze near the low end kills the foliage cold, which is why it fires best as a spring or fall plant rather than a winter one.
Humidity
Plain outdoor humidity is all it wants, so skip chasing a number. Airflow beats moisture here, since crowded, still plantings are exactly where aphids and rot dig in.
Feeding
Ditch the fertilizer in all but the poorest soil. As a cover crop phacelia scavenges the nitrogen already down there instead of begging for more, and a heavy dose only pumps out soft, aphid-bait foliage.
Pruning
There's no real pruning to tackle. Deadhead the spent clusters to keep the bloom firing and to rein in self-seeding, and if you run it as a cover crop, mow or till the whole stand at flowering before it sets seed.
Repotting
none
Size & spacing
Plants shoot up to 1 to 3 feet (30 to 91 cm) tall with a spread of about 8 to 18 inches (20 to 45 cm). Sow them thick as a cover crop and they lock together and smother weeds, while a thinner stand hands each plant room and better airflow.
When to plant
Phacelia sprints through its season. Direct sow it in early spring the moment the soil works up, or in fall where winters stay mild, and it bursts into bloom about 6 to 8 weeks later. Stagger sowings every couple of weeks to keep the color surging, and count on a hard frost to shut the stand down.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: Generally direct-sown; if starting indoors, sow 4 to 6 weeks before last frost in darkness (light inhibits germination)
- Plant: Direct sow in early spring when soil is workable, or in fall in mild-winter climates; sow seed about 0.25 inch deep when soil temperatures are below 68 degrees F
- Harvest: Late spring through summer; blooms roughly 6 to 8 weeks after sowing over a long period
Hardiness
USDA hardiness zones: 3–10
Temperature: down to -40°C
Troubleshooting
Phacelia barely throws a problem your way, and what little does go sideways almost always traces to wet soil or its raring-to-reseed streak. Match what you spot below and jump on it early. Nip a small issue now and it never gets the chance to spread.
Fresh seedlings springing up where none were sown
Phacelia throws seed with gusto, and once those coiled seed heads dry and split they load the soil with a seed bank that erupts after the next rain. Win the timing and you win the game. Mow, till, or yank the stand at peak bloom before the seed hardens, and snip the spent clusters so not one ripens.
Fix:
- Mow, till, or pull plants at flowering before seed matures
- Deadhead spent flower clusters before they dry and shatter
- Hand-pull or hoe volunteer seedlings while young
Wilting, yellow plants slumped over rotted roots
Phacelia loathes soggy ground, and wet feet unleash root rot that turns the roots soft and dark and eats away the crown at soil level. A collapsed plant is done, so pull it fast and chase down the drainage. Get it into sandy, gravelly, or loamy soil and dodge the low spots that stay wet.
Fix:
- Improve drainage and stop overwatering
- Remove and discard collapsed plants
Blooms racing through and the patch bowing out early
That quick exit is pure phacelia, not a stumble. It runs as a short-lived annual, blazing through a few weeks of flower per sowing before its soft foliage blackens the instant a hard frost dives near 18°F (-8°C). Keep the show blazing by launching a fresh patch every 2 to 4 weeks, and fire off a new sowing the moment the cold clears out.
Fix:
- Make successive (succession) sowings every 2 to 4 weeks to extend continuous bloom
- Replace winterkilled plantings with a new sowing once frost danger passes
Soft insects piling onto sticky new stems
Those piles are aphids, homing in on soft or stressed new growth and dribbling sticky honeydew as they feed. Blast them off with a hard jet of water and shrug off the stragglers. Better yet, phacelia summons hoverflies, lacewings, and parasitic wasps that swoop in and mop up the aphids for you.
Fix:
- Spray off colonies with a strong jet of water
- Tolerate light infestations, as phacelia attracts predatory and parasitic beneficial insects that help control aphids
Toxicity
Phacelia is easygoing company in the garden, non-toxic to pets, livestock, and people across the board, with no poison in any part of the plant. The one thing to flag is the hairy foliage, which can raise an itchy rash on people who handle it and react, so glove up before you pull or mow a stand.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
Cats can prowl right through it. A nibbled leaf does zero harm, since phacelia packs no toxin that bothers them.
Dogs None
Dogs get a free pass. They can charge through or chomp a leaf without a hitch, and phacelia never lands on poison-control lists.
Horses Safe
Horses can graze phacelia all day and stroll off unharmed, because it holds nothing toxic to them.
Rabbits Safe
Rabbits can chow down on the leaves freely, with no harmful compounds anywhere in the plant.
Livestock Safe
Cattle, goats, and sheep thrive alongside phacelia, and growers toss it straight into pasture cover-crop mixes.
Birds Safe
Birds have a blast here with no risk at all. Plenty flock to the seed heads, and the plant poses no poisoning threat.
People Safe
Nothing here will poison you, full stop. The lone catch is the foliage, whose glandular hairs can raise an itchy rash on sensitive skin, so snap on gloves before you handle or mow a stand.
Phacelia foliage bears glandular hairs and contains skin-sensitizing compounds (geranylhydroquinone and related substances). Some people develop allergic contact dermatitis (an itchy skin rash) from handling the leaves. Wear gloves when handling or terminating the plants if you are sensitive, and supervise children who handle the foliage.
Varieties
Most seed sold as phacelia is the everyday lacy type, but a close cousin crashes wildflower plantings now and then. These two are the ones worth telling apart.
Lacy phacelia (Phacelia tanacetifolia)
This is the go-to cover-crop and bee-magnet type, easy to peg by its finely cut fern-like gray-green leaves and coiled, one-sided sprays of lavender-blue bells whose long stamens shoot well past the petals.
California bluebell (Phacelia campanularia)
A close ornamental cousin grown for its knockout deep gentian-blue bells, it hunkers lower and bushier than lacy phacelia and wins fans as a desert wildflower instead of a cover crop.
How to propagate
Phacelia grows from seed and nothing else, and it charges into it eagerly, both from a packet you sow and from the seed a standing patch flings on its own.
SeedEasy
Direct sow in early spring, or in fall in mild-winter climates; make successive sowings to extend bloom · Germinates in about 15 to 30 days; flowers roughly 6 to 8 weeks after sowing
Phacelia rockets up from seed sown right where it will grow. Drop the seed about a quarter inch deep once the soil dips below 68°F (20°C), since light and warmth above that stall germination. Sprouts break ground in 15 to 30 days and flowers pop about 6 to 8 weeks after sowing, and once a patch takes off it reseeds itself with abandon.
Myths
Names like scorpionweed and fiddleneck mean phacelia is a dangerous garden plant.
Don't buy the spooky names for a second. They just capture the coiled, scorpion-tail curl of the flower clusters and flag nothing dangerous. Phacelia ranks among the finest bee and beneficial-insect plants you can grow, and it is non-toxic to pets and people. The only real catch is a chance of skin irritation from handling the hairy foliage if you happen to be sensitive.
Phacelia fixes nitrogen like clover or vetch.
Tempting thought, but no. Phacelia belongs to the borage and waterleaf family, worlds away from the legumes, so it adds no new nitrogen to the soil. What it does as a cover crop is haul up the nitrogen already there, bank it, and hand it back as it breaks down.