Seed Starting Guide | Pups N' Blooms

General Seed Starting: A Few Things I've Learned Along the Way

Vermiculite for Light-Covered Seeds

Whenever a seed variety calls for light coverage, I use a thin layer of vermiculite rather than regular potting mix.

Seed-Starting Trays

I sprinkle cinnamon over my seed-starting trays as my personal practice for managing algae growth.

A Note About Growing Recommendations

Growing times, germination rates, and planting recommendations are estimates. Actual results depend on weather, soil conditions, growing environment, and individual gardening practices.

Always consider your local climate, soil temperature, and growing conditions when planning your garden.

Happy growing!

- Erika

Days to Maturity: 90–100 days
Life Cycle: Annual
Light: Full Sun
Soil Requirements: Rich, well-drained soil

Plant Height: 24–36 inches
Plant Spacing: 9–15 inches
Days to Germination: 10–12 days
Germination Temperature: 65–70°F

Starting & Growing

Indoor Starting (Recommended)

Sow 4–6 weeks before planting outdoors. Barely cover seeds, as light aids germination. Once the first true leaves appear, transplant seedlings into cell packs or larger containers.

Grow transplants at 50–55°F to help prevent stretching. Harden off seedlings before transplanting outdoors after the last frost.

Direct Sowing

Successive plantings every 2–3 weeks until late spring can provide a continuous supply of flowers. Plants may require support as they grow.

Harvesting

For fresh-cut flowers, harvest when blooms are almost fully open.

Pups N' Blooms Tip

In my western Washington garden, Scabiosa has been surprisingly cold tolerant. Mine has never experienced frost damage and has remained in the garden for two growing seasons and counting, even though it's technically grown as an annual.

I support mine by corralling the plants between posts using fishing line. This helps keep the stems upright as they grow.

Days to Maturity: 75–85 days
Life Cycle: Annual
Light: Full Sun
Soil Requirements: Rich, deep, loamy, moist, well-drained soil. Preferred pH 6–7.

Plant Height: Varies

Plant Spacing: 4–8 inches

Days to Germination: 14–21 days

Germination Temperature: 55–65°F

Starting & Growing

Indoor Starting (Recommended)

Sow 4–5 weeks before planting outdoors. Plant seeds ¼–½ inch deep in deep-cell trays or containers. Darkness is required for germination.

Avoid disturbing roots.

Direct Sowing

Sow 2–3 seeds every 6 inches, ¼–½ inch deep. Seedlings can tolerate a light frost.

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Thin seedlings as needed once the first true leaves appear.

Sweet peas require climbing support or a trellis.

Pinching

Pinch plants when they reach 6–8 inches tall to encourage branching and more flowers.

Harvesting

Harvest when approximately half the flowers on a stem are open. Regular harvesting encourages additional blooms.

Vase Life: 4–6 days

Pups N' Blooms Tip

In my Zone 8b western Washington garden, St. Patrick's Day is my signal to direct sow sweet peas. It's my personal rule of thumb for that sweet spot when the soil is workable and the weather is still cool.

I personally never soak my sweet pea seeds. If starting in trays, I leave them outdoors under the awning of the house so they receive some natural moisture without getting completely soaked by the rain.

As summer approaches, I lightly mulch around the plants to help keep their roots cool. Sweet peas don't enjoy summer heat, and keeping their roots cooler helps them through the season.

Days to Maturity: 65–70 days to flowers
Life Cycle: Annual
Light: Full Sun
Soil Requirements: Average soil with good drainage

Plant Height: Varies

Plant Spacing: 2–9 inches

Days to Germination: 10–14 days

Germination Temperature: 60–65°F

Starting & Growing

Indoor Starting

If starting indoors, sow 4–6 weeks before planting outdoors. Transplant carefully to minimize root disturbance.

Direct Sowing (Recommended)

Nigella is best direct sown because plants are sensitive to root disturbance.

Sow as soon as the soil can be worked. Cover seeds very lightly, as light is required for germination.

For continuous flowers, sow successive plantings every 2–3 weeks early in the season. Fall sowing is also possible in areas with mild winters.

Harvesting

Harvest flowers when buds are fully colored.

Pups N' Blooms Tip

I like to scatter-sow my Nigella seeds throughout the garden in spring. Once seedlings start popping up, I thin out any areas that are too crowded. If I'm careful when removing them, I'll sometimes transplant them to another spot in the garden.

I also grow Nigella in beds that receive plenty of pine needles. Pine needles can contribute to more acidic soil conditions, but I've found that my Nigella doesn't seem to mind!

Days to Maturity: 65–75 days
Life Cycle: Annual
Light: Full Sun
Soil Requirements: Well-drained soil. Preferred pH 6–7.

Plant Height: Varies

Plant Spacing: 12–15 inches

Days to Germination: 7–10 days

Germination Temperature: 70–75°F

Starting & Growing

Indoor Starting

Sow 4–6 weeks before planting outdoors. Cover seeds with growing medium and keep the soil surface moist until emergence.

Grow transplants at approximately 62–65°F until ready to transplant.

Direct Sowing (Recommended)

Direct sow after the danger of frost has passed.

Spacing & Support

Red Spike is an upright plume variety. Support is recommended as plants grow.

Standard spacing is 12–15 inches. For thinner, more manageable upright stems, tighter spacing of 3–6 inches can be used.

Harvesting

Harvest when at least three-quarters of the flowers on the plume are open.

Vase Life: 7–10 days.

Days to Maturity: 80–85 days
Life Cycle: Annual
Light: Full Sun to Part Shade
Soil Requirements: Moderate to well-drained soil

Plant Height: 18–24 inches

Plant Spacing: 9–12 inches

Days to Germination: 5–8 days

Germination Temperature: 65–70°F

Starting & Growing

Indoor Starting

Sow 3–4 weeks before your last expected frost. Transplant outdoors after the last frost.

Direct Sowing

Sow as soon as the soil can be worked. The standard sowing recommendation is to cover seeds lightly, as darkness is required for germination.

Harvesting

Harvest when approximately half of the florets on a stem are open.

Pups N' Blooms Tip

I simply scatter-sow my Chinese Forget-Me-Nots. I don't even bother covering the seeds.

When I want to trim plants back before the seeds become a nuisance, I scatter the seed where I'd like new plants to grow next.

A Word of Caution for Dog Owners

The mature seeds are like little burrs! If you have dogs, be prepared to pick seeds out of their fur once these plants go to seed. Your dogs will find them!

Days to Maturity: 75–90 days
Life Cycle: Annual when grown from seed
Light: Full Sun
Soil Requirements: Well-drained soil

Plant Height: 40–60 inches

Plant Spacing: 9–12 inches

Days to Germination: 3–5 days

Germination Temperature: 65–70°F

Starting & Growing

Indoor Starting (Recommended)

Sow 4–5 weeks before your last expected frost. Cover seeds with growing medium and keep the soil surface moist until emergence.

Once seedlings develop their first true leaves, transplant into larger cell packs or containers.

Avoid allowing plants to become root bound and take care not to disturb their roots.

Direct Sowing

Direct sow after the last frost, once soil temperatures reach 65–70°F.

Sow ¼ inch deep. Cover lightly but firmly and keep the soil surface moist until germination.

Thin seedlings to 9–12 inches apart once the first true leaves appear.

Harvesting

Harvest flowers before blooms are completely open.

Dahlia Seeds to Tubers

Dahlias grown from seed can produce tubers that may be saved, stored, and planted the following spring!

In fall, after plants have died back but before the ground freezes, cut plants back to 2–4 inches above the soil line. Carefully dig the tubers and remove excess soil before storing.