How Many Rosemary Seeds Per Hole to Plant

By Priya Sharma · January 24, 2026

How Many Rosemary Seeds Per Hole Should You Plant?

Plant 2–3 rosemary seeds per hole to ensure successful germination. Since rosemary seeds have a moderate germination rate (typically 50–70%), planting multiple seeds increases the likelihood of at least one sprouting. After seedlings develop their first true leaves, thin to the strongest plant per hole to avoid overcrowding and promote healthy growth.

Why the Number of Seeds Per Hole Matters

Getting the seed density right is essential for maximizing your chances of growing healthy rosemary plants. Too few seeds may result in no germination; too many can lead to competition for light, water, and nutrients.

Common Issues with Incorrect Seed Spacing

Low germination due to old or poor-quality seeds
Overcrowded seedlings that are weak and prone to disease
Increased risk of damping-off from poor air circulation
Wasted soil, space, and time managing excess seedlings

Best Practices for Planting Rosemary Seeds

To grow rosemary successfully from seed, follow these expert-recommended steps:

Step-by-Step Planting Guide

Use fresh seeds (less than 1 year old) for higher germination rates.
Fill seed trays or small pots with well-draining seed starting mix.
Sow 2–3 seeds per hole, about 1/8 inch (3 mm) deep.
Keep soil consistently moist but not soggy.
Place in a warm area (70–75°F / 21–24°C) with bright, indirect light.
Germination typically takes 15–25 days.
Once seedlings have 2–3 sets of true leaves, thin to one strong plant per hole.

Germination Rates and Seed Viability

Rosemary seeds are known for inconsistent germination. Even under ideal conditions, not every seed will sprout. Understanding germination percentages helps determine how many seeds to plant per hole.

Seed Age	Average Germination Rate (%)	Recommended Seeds Per Hole
Fresh (0–6 months)	65–70%	2
6–12 months	50–60%	2–3
12–18 months	30–40%	3–4
Over 18 months	10–20%	4+ (or replace seeds)

Table data source:RHS, University of Minnesota Extension

The data shows that seed age significantly impacts germination success. Fresh seeds require fewer per hole, while older seeds need higher sowing density to compensate for reduced viability. For optimal results, always use high-quality, recently harvested seeds stored in a cool, dry place.

Alternative Methods: Using Seedlings vs. Direct Seeding

While starting from seed is cost-effective, many gardeners opt for seedlings due to rosemary’s slow and erratic germination. Here’s a comparison:

Seed Starting: More economical, wider variety selection, but requires patience and consistent care.
Transplanting Seedlings: Faster establishment, higher survival rate, ideal for beginners.

If using seedlings, space them 8–12 inches apart when transplanting outdoors after the last frost.

Frequently Asked Questions About Planting Rosemary Seeds

How deep should I plant rosemary seeds?

Plant rosemary seeds about 1/8 inch (3 mm) deep. They require light to germinate, so avoid burying them too deeply. A thin layer of soil or vermiculite is sufficient.

How long does it take for rosemary seeds to germinate?

Rosemary seeds typically take 15 to 25 days to germinate under optimal conditions (70–75°F). Some may take up to 30 days, so patience is key.

Should I soak rosemary seeds before planting?

Yes, soaking seeds in lukewarm water for 12–24 hours can improve germination rates by softening the hard seed coat and promoting moisture absorption.

Can I plant more than 3 rosemary seeds per hole?

You can, but planting more than 3 increases crowding and thinning work later. It's better to use 2–3 high-quality seeds than overcrowd the hole.

When should I thin rosemary seedlings?

Thin seedlings once they have developed 2–3 sets of true leaves. Choose the healthiest, most vigorous plant and snip the others at soil level to avoid disturbing roots.