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Phacelia cover crop and bee forage
Photo: "Am Feldrand" by Michael Mueller · CC BY 2.0

Phacelia cover crop and bee forage

Annual · Boraginaceae

Phacelia is a fast cover crop and one of the best bee-attracting flowers gardeners can sow for short windows between food crops. It makes fine roots, quick canopy, and purple blooms that support pollinators and beneficial insects, which is why it is often used as both a cover crop and a habitat plant. It suits gardeners who want rapid bloom and ecosystem services from a short planting. Key facts: 45–60 days to maturity from direct sowing, 6+ hours of sun, 6–12" spacing. Not recommended for containers.

Updated June 1, 2026 · Backed by 7 cited sources
Overview

At a Glance

The essentials first: timing, light, spacing, seed-starting, container fit, and overall size.

Days to maturity
45–60 days
from direct sowing
Sun
6+ hours
Full Sun 6-8 Hours
Spacing
6–12"
between plants
In practice

Dense sowing is fine for cover crop function; thin more aggressively if growing for edible flowers.

Seed start
0 weeks
before transplant
Container
No
Needs 5+ gal if attempted
Height
0.5–4 ft
at maturity
Planting window

Zone Planting Guide

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Season sequence

Phacelia Cover Crop Cycle

A short-season cover crop. It has no fixed place in the year, so what matters is the window you can sow it in.

  1. 1
    Cool-season window. Seed as a cool-season annual forb where a nitrogen catch crop, short-term soil cover, and insectary bloom are desired.
  2. 2
    Vegetative growth. Use as soil cover and nutrient capture. This is also the window when nitrogen value is highest, before flowering. Phacelia can host tarnished plant bug (Lygus lineolaris), which damages fruiting vegetables, so keep a stand away from tomatoes, peppers, cucumbers and squash rather than interplanted through them.
  3. 3
    Before mature seed or before bed turnover. Terminate by mowing or incorporation before seed maturation if volunteers would be a problem. Sources disagree on how readily phacelia self-seeds: NC State's plant profile records that it self-seeds readily, while the SARE FNE13-781 trial in Vermont found no volunteer phacelia in any plot the following season. Treat volunteer behaviour as unknown for your site and watch the first season.
  4. 4
    After termination. Allow residue to settle before seeding small-seeded vegetables; use local timing because phacelia-specific home-garden termination data is limited.
Common questions

Phacelia FAQ

Every answer is assembled from this cultivar's own record, so the figures match the rest of the page.

How many days to maturity for Phacelia cover crop and bee forage?

Phacelia takes 45–60 days to reach maturity from direct sowing.

How far apart should you plant Phacelia cover crop and bee forage?

Space Phacelia 6–12 inches apart, with 12–18 inches between rows.

How much sun do Phacelia cover crop and bee forage need?

Phacelia needs at least 6 hours of direct sun a day.

How much water do Phacelia cover crop and bee forage need?

Phacelia needs 0.75–1.25 inches of water a week, counting rainfall.

What soil pH do Phacelia cover crop and bee forage need?

Phacelia grows best in soil with a pH of 6–7, ideally around 6.5.

How tall do Phacelia cover crop and bee forage get?

Phacelia reaches 0.5–4 feet at maturity.

How do you start Phacelia cover crop and bee forage from seed?

Sow seed straight into the garden once the soil reaches 40°F.

What temperature do Phacelia cover crop and bee forage seeds need to germinate?

Phacelia seeds germinate best at 65°F, within a workable range of 45–70°F, and take 5–14 days to emerge.

Can you grow Phacelia cover crop and bee forage in containers?

Phacelia is not recommended for container growing. It would need at least 5 gallons if attempted, and compact varieties suit pots far better.

When is Phacelia cover crop and bee forage in season?

Phacelia is a cool-season crop, in season during spring and fall in most regions. Plants reach harvest 45–60 days after direct sowing and prefer temperatures below 75°F.

Resilience

Plant Health

Stress tolerance, resistance notes, and the most common problems to watch for as plants mature.

Tolerance
Heat: Moderate Cold: Hardy Drought: Moderate

Watch for these first

Sort
Issue Severity Category Peak window
Damping off Pythium spp. / Rhizoctonia solani / Fusarium spp.
High Disease May–Aug Peak window months: May, Jun, Jul, Aug.

A seedling killer caused by several different fungi working together. It hits vegetables, flowers, herbs, microgreens, and cover-crop seedlings the same way — seeds rot before they emerge, or young seedlings collapse right at the soil line. Wet seed-starting mix and poor airflow in seedling trays are the classic conditions.

Triggers: Wet soil or starting mix, poor drainage, seedlings packed too tightly, contaminated trays or media, and stagnant air all favor damping-off.

On Phacelia: Cold, wet seedbeds or overly dense sowing can kill seedlings.

Prevention: Use clean seed, shallow sowing, and thin dense stands.

Risk fades when: Drying the soil surface and improving airflow slows new spread. Collapsed seedlings don't recover, but the rest of the tray can be saved.

Damping off symptoms
Damping off of coffee seedlings caused by Fusarium sp. — Photo: Scot Nelson · CC0 1.0
Powdery mildew Golovinomyces cynoglossi
Low Disease May–Aug Peak window months: May, Jun, Jul, Aug.

A Boraginaceae powdery mildew supported for forget-me-not, where it causes dense white fungal growth on leaves and stems. Current source support is strongest for forget-me-not specifically — don't auto-add borage unless plant data references and supporting sources are verified.

Triggers: High humidity with dry leaf surfaces, aging or crowded plants, and poor airflow all favor the disease.

On Phacelia: Late-season humidity can coat foliage and blooms.

Prevention: Improve airflow and avoid crowding.

Risk fades when: Pressure eases when weather moves out of mild humid conditions and infected annual foliage is cleared.

Feeding & picking

Nutrition & Harvest

How hungry the plant is, what ripe harvest looks like, and how long the crop keeps after picking.

Feeding
Nutrition
Feeding intensityNone feeder
Timing
Harvest

Terminate at early bloom for easy incorporation and maximum tenderness.

Expected yield0 lbs/plant
Storage Not normally stored; use as mulch or incorporation residue the same day.
Plant relationships

Companion Planting

Helpful neighbors can support growth or deter pests. Keep antagonistic plants separated to reduce stress and competition.

Good companions
Buckwheat
Both flowering cover crops enhance summer pollinator forage during floral dearth periods.
What it does5
Soil building Research supported
Scavenges phosphorus almost three times as effectively as barley and more than ten times as effectively as rye. Root acids activate slow-release sources such as rock phosphate, releasing phosphorus to later crops as the dead plant material breaks down.
Clark 2007, Managing Cover Crops Profitably, 3rd ed. (SARE)
Beneficial insects
Attracts hoverflies, predatory wasps, minute pirate bugs, ladybeetles.
Weed control Research supported
Fast-closing dense canopy smothers warm-season annual weeds, mainly through shading and competition. Successive dense seedings can also suppress perennials such as Canada thistle and quackgrass.
SARE, Managing Cover Crops Profitably, 3rd ed.; eOrganic
Soil building
Fibrous roots loosen compacted topsoil. Rapid decomposition adds organic matter.
Pollinators
Excellent bee forage; flowers can produce nectar continuously for several weeks.
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What you'll need

Growing Supplies

Hand-picked for your Phacelia, with the extension research behind every recommendation.

Mulch / landscape fabric

Nearly every garden benefits from mulch for weed suppression, moisture conservation, and soil temperature moderation. For most home gardeners, quality organic mulch is the better buy over landscape fabric.

Source: Penn State Extension; Wisconsin Horticulture; Illinois Extension

Our pick

Cleaned Wheat Straw Mulch (3 cu ft, ~20 lbs)

Thoroughly cleaned wheat straw at 3 cubic feet, marketed specifically for vegetable gardens rather than animal bedding or decoration. Better per-pound economics than the 1 cu ft option, with the same extension-recommended material. Strong sales volume (2K+ bought past month) supports product consistency.

paid link ?When you shop on Amazon using this link, SoilStack earns a small commission at no extra cost to you. It's how we keep the site free and the calendar ad-free. Every product on this page was hand-selected based on university extension research. When you shop on Amazon using this link, SoilStack earns a small commission at no extra cost to you. It's how we keep the site free and the calendar ad-free. Every product on this page was hand-selected based on university extension research.
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Drip irrigation / soaker hose kit

Every gardener benefits from putting water at the root zone instead of on the leaves, because drip and soaker systems reduce foliar disease pressure by limiting leaf wetness and soil splash. A quality kit should include a backflow preventer, filter, pressure reducer, and UV-resistant tubing.

Source: Iowa State University Extension; Colorado State University Extension; UMass Extension

Our pick

Complete Garden Drip Irrigation Kit

Designed for beginners with a step-by-step setup guide. Adjustable emitters, both tubing sizes, and all connectors included.

paid link ?When you shop on Amazon using this link, SoilStack earns a small commission at no extra cost to you. It's how we keep the site free and the calendar ad-free. Every product on this page was hand-selected based on university extension research. When you shop on Amazon using this link, SoilStack earns a small commission at no extra cost to you. It's how we keep the site free and the calendar ad-free. Every product on this page was hand-selected based on university extension research.
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Row cover / frost blanket

Row cover adds frost protection, speeds early growth, and physically excludes insect pests without spraying. Look for spun-bonded fabric with a stated weight and frost rating, UV resistance, and enough width for hoops or low tunnels.

Source: University of Maryland Extension; University of New Hampshire Extension; Colorado State University Extension

Our pick

Frost Blanket (10'x30')

Thicker 1.2 oz fabric rated to protect down to 28°F. Covers 300 sq ft — enough for multiple raised beds in a single sheet.

paid link ?When you shop on Amazon using this link, SoilStack earns a small commission at no extra cost to you. It's how we keep the site free and the calendar ad-free. Every product on this page was hand-selected based on university extension research. When you shop on Amazon using this link, SoilStack earns a small commission at no extra cost to you. It's how we keep the site free and the calendar ad-free. Every product on this page was hand-selected based on university extension research.
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Garden shade cloth

K-State Research and Extension and University of Maryland Extension recommend shade cloth as a heat-management tool for vegetable gardens, with 30 percent shade rating most effective for tomatoes, peppers, and fruiting crops, and 40 to 50 percent for protecting heat-sensitive greens during hot summer months. University of Delaware research found 30 percent black shade cloth tripled marketable yield for bell peppers compared to unshaded plants, and Purdue trials showed shade cloth reduced maximum daily temperatures by 8 to 10 degrees Fahrenheit. Choose knitted polyethylene with reinforced grommets every 18 to 24 inches, mount on hoops or a frame with open sides for airflow, and remove or vent during prolonged wet weather to avoid increased humidity in the canopy.

Source: K-State Research and Extension; University of Maryland Extension; University of Delaware Cooperative Extension; Purdue University Extension

Our pick

30% Sun-Block Shade Cloth (6x10 ft)

Same 30 percent rating in the typical home-garden size that fits a 4 by 8 raised bed plus working overhang. Knitted polyethylene with grommets for tie-down. Strong volume signal (3.8K reviews) supports consistent product quality across orders.

paid link ?When you shop on Amazon using this link, SoilStack earns a small commission at no extra cost to you. It's how we keep the site free and the calendar ad-free. Every product on this page was hand-selected based on university extension research. When you shop on Amazon using this link, SoilStack earns a small commission at no extra cost to you. It's how we keep the site free and the calendar ad-free. Every product on this page was hand-selected based on university extension research.
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