Rosemary Seeds: Where To Buy & Germination Tips for Success

This versatile Mediterranean herb was once named “mist of the sea” due to its gray-tinged foliage resembling mist on the sea cliffs.

Much like the crashing of waves, rosemary packs an aromatic punch in your garden – especially when grown as pathway edging you can brush past.

Rosemary is a notoriously slow-grower, but don’t fret! You’ll find the best chance for success with my seed recommendations, germination steps, care tips, and more.

Rosemary at a Glance

Popular Rosemary Varieties

Rosemary is an evergreen shrub with fragrant needle-like foliage, and the common variety of Salvia rosmarinus typically produces blue flowers and grows to 4 feet tall and wide.

Rosemary is generally pest and disease free and will attract butterflies, bees, and hummingbirds to your landscape.

This well-loved herb has been in use for so long, however, that many hybrid versions have emerged bearing different flower coloring, cold resistance, and height (tall, upright types and low-growing ground cover).

Let’s look at 8 of the most popular rosemary varieties:

• ‘Benenden Blue’ – Semi-upright bush, 3 feet tall & 4 feet wide, dark blue flowers, very fine needles.
• ‘Arp’ – Cold-hardy variety, 4 feet tall & wide, bright-blue flowers, light-green foliage, lemon scented.
• ‘Miss Jessop’s Upright’ – Upright, compact growth suited to hedging; 5 feet tall & 3 feet wide; deep-blue flowers.
• ‘Joyce de Baggio’ or ‘Golden rosemary’ – Variegated foliage changing from bright yellow to dark green during growth, bushy growth, 2-3 feet tall & wide, violet-blue flowers.
• ‘Majorca Pink’ – Semi-upright growth, 4 feet tall & 2 feet wide, small pale-pink blooms, dark-green foliage.
• ‘Prostratus Group’ – Low-growing shrub, arching prostrate stems, 2 feet tall & 2-3 feet wide, lavender-blue flowers.
• ‘Severn Sea’ – Arching growth, highly aromatic dark-green foliage, 3 feet tall & wide, bright-blue flowers.
• ‘Santa Barbara’ – Trailing variety of vigorous growth, 3 feet tall & wide, small pale-blue flowers.

Best Places To Buy Rosemary Seeds

Rosemary Seed Planting & Germination

Supplies:

• Seed starter mix
• Seed tray with humidity dome
• Misting bottle
• Heat mat
• Grow light
• 4-inch terracotta pots

1. Fill a Seed Tray With Starter Mix & Sow Seeds Liberally

Starting in early fall (or when 3-6 months of warmer weather is expected), moisten the seed starter mix with a misting bottle, and fill each tray cell with the mix.

As germination rates are quite poor, sprinkle at least 4-5 seeds into each cell, and press each one lightly into the soil – but ensure they are not covered by the mix.

2. Mist the Seeds & Store Tray in a Bright, Warm Setting

Lightly mist the tray so that the soil surface feels evenly moist, and place a humidity dome/covering over the tray.

Next, place the tray on a heat mat and in an area of direct sunlight – this could be a south-facing windowsill or under full-spectrum grow lights (the latter is probably best during fall/winter).

Ensure your heat mat thermostat is set to at least 59°F for germination to occur, though 64-75°F is ideal.

3. Maintain Moist Soil & Expect Germination in 3 Months or Less

Check the soil surface regularly to ensure it doesn’t dry out, and mist well enough to help it stay moist, replacing the humidity lid/dome afterward.

Depending on environmental conditions, germination may occur as soon as 3-4 weeks or as long as 3 months. Uneven watering and poor light can slow things down.

4. Remove Humidity Cover Once Growth Appears & Cease Watering

Once the seedlings emerge through the soil, remove the humidity lid, but keep the tray in direct light/heat.

Stop moistening the soil at this point – rosemary seedlings are prone to “damping off” (collapsing due to fungal growth in cool, wet conditions), so let the soil dry for about 3-4 days.

5. Transplant Seedlings Into Pots Once They Reach 4-6 Inches

When the seedlings measure 4-6 inches, transplant them individually into 4-inch pots filled with peat-free compost, and water lightly to moisten the soil.

Gradually acclimatize your rosemary pots to the outdoors by placing them outside for 1-2 hours each day until the threat of frost has passed.

Around 2 weeks after your last local frost date, you can safely transplant your potted rosemary into a full-sun planting site of loamy soil – spacing each seedling at least 3 feet apart.

Alternatively, you can keep them in pots to bring them indoors over winter if you prefer.

5 Tips for Growing Rosemary From Seed

1. If germination fails in ideal conditions, you may need to ‘cold stratify‘ your seeds (placing the seeds in a climate of 37-38°F for 4 weeks before returning them to warmth) – this tricks them into experiencing a cold snap to break their dormancy cycle and encourage germination!
2. You may have better luck germinating your rosemary seeds in a complete propagator kit (find it here) – this is essentially a 3-in-1 seed tray, heated base, and humidity dome with an adjustable vent for controlled air circulation.
3. Instead of using a commercial seed starter mix, you can easily make your own potting soil with a combo of peat moss and vermiculite – this helps retain water while simultaneously aerating the soil to help the juvenile roots avoid rot.
4. Don’t overwater the soil – the surface should only be misted enough to feel moist – but not soggy. If you overdo it (especially with a humidity lid trapping in all that excess moisture), you’ll increase the risk of fungal growth.
5. Record your progress – keep a note of all your trials and errors with germinating rosemary from soil and grow lights used to misting frequency and success rates for future reference.

Growing & Caring for Rosemary 

 

The above steps should help you coax this hard-to-germinate seed into a healthy young plant, but once you do, this is no time to take a back seat!

You don’t want your hard work and patience during the germination phase to go to waste with poor care at the final hurdle – so whether planted in pots or a garden bed, make sure your rosemary has everything it needs.

Ideal Soil

Rosemary will thrive in loamy soil with a pH reading between 6.0-7.0 (don’t rely on guesswork – use a pH meter to be sure).

This creates a sandy, well-draining composition that’s just acidic enough to retain a good balance of nutrients that will encourage growth and flowering.

Lighting Requirements

While rosemary is shade tolerant, aim for a full-sun location so it’s afforded at least 6 hours of daily sunlight – an easterly area can be perfect as the plant can enjoy full, direct sunlight until noon.

Watering & Fertilizing

For garden-planted rosemary, water well enough to keep it moist for the initial 2 weeks – after this let rainfall do the rest, and only provide supplemental watering during a severe drought.

For potted rosemary plants, water whenever the top inch of soil feels dry to the touch, and aim to keep the soil moist.

Too much fertilizer can risk damaging rosemary but if you must, use an organic non-acidic feed with a 20-20-20 NPK ratio (I recommend this one) lightly every other week during spring/summer.

Harvesting

Begin harvesting the following year once the rosemary has become established. When ready, use pruning shears to remove whole stems of rosemary or gently pull small sprigs off the stem by hand.

Hang sprigs/stems in bunches upside down in a cool, dark place like your kitchen pantry – once dried, you can pinch the needles from the sprigs and store them in a sealed jar or bag in a pantry until needed.

Rosemary Common Questions: 

Is Rosemary Hard To Grow From Seed?

Rosemary can be tricky to grow from seed due to its poor germination rate of 30-50% and its slow growth.

Over-sowing (planting four seeds or more in each cell) is recommended for greater success. Some gardeners have found it easier to grow rosemary from stem cuttings, just be sure to use green flexible shoots.

How Long Does Rosemary Take From Seed?

Under fantastic growing conditions, rosemary may germinate in a matter of weeks and will be ready for planting within a few months, taking a total of 6 months.

However, as germination can be notably slow, it will likely take closer to a year to go from seed to an established garden plant.

Should You Soak Rosemary Seeds Before Planting?

Some gardeners advocate soaking rosemary seeds in tepid water for 12 hours prior to sowing to prime the seed.

This can help introduce seeds to the germination process by governing the moisture content and temperature. Take care not to soak for longer than 48 hours to avoid rot.

Why Won’t My Rosemary Seeds Germinate?

Rosemary seeds may need to experience cold stratification before sowing.

Unsuccessful germination can also be due to fungal rot as a result of waterlogged soil, so ensure the soil is lightly moist but not soggy.

Consistent temperatures of 64-75°F are also crucial as cold, wet soil can breed seed-weakening pathogens.