How to Start Phlox From Seed?

While it’s often propagated through division or cuttings, starting phlox from seed is a simple and cost-effective way to grow these plants. However, there are things that you need to do step-by-step to make sure they’ll grow as you like.

In this article, we’ll show you how to start phlox from seed, from choosing a location to caring for the plants as they grow. In addition, you’ll know how to prevent them from dying, even if you’re a beginner.

7 Steps to Start Phlox From Seed

Starting phlox from seed can be done indoors or outdoors, depending on your climate and preferences. Here are the steps to follow:

Step #1: Choose a Sunny Location

Phlox needs full sunlight to grow. So, choose a location that gets at least six hours of direct sunlight a day.

Step #2: Prepare the Soil

Phlox prefers soil that’s rich in organic matter. Hence, you can add compost to improve its fertility and texture. You should also make sure that the soil is well-draining.

Additionally, it should be slightly acidic with a pH of 6.0 to 7.0. Before sowing, loosen the soil and remove any debris or weeds.

Step #3: Sow the Seeds

Sow the phlox seeds in the prepared soil in spring or early fall. Sprinkle the seeds over the soil surface, then cover them with a thin layer of soil or compost. Water gently to settle the soil.

Step #4: Keep the Soil Moist

Maintain soil moisture because too much water can cause the seeds to rot. Water the phlox seedlings when the soil feels dry to the touch. Avoid letting the soil dry out completely, as this can stress the phlox.

Step #5: Thin the Seedlings

Once the seedlings have grown a few inches, thin them out to prevent overcrowding. Space the seedlings 6 to 12 inches apart, depending on the variety.

Step #6: Harden Off the Seedlings

Before transplanting the seedlings to your garden, gradually acclimate them to outdoor conditions.

Start by placing them outside in a sheltered, shady location for a few hours. Then gradually increase the amount of time they spend outside over several days.

Step #7: Transplant the Seedlings

When the seedlings have grown large enough to handle, transplant them into their permanent location in the garden.

Choose a sunny, well-draining spot and plant them at the same depth they were growing in their containers.

Is There a Best Time to Plant Phlox Seeds?

Yes! You can start planting seeds either in the fall or in spring. If you’re sowing in the fall, plant the seeds about 6–8 weeks before the first frost date. If sowing in the spring, wait until the last frost date has passed.

How Long Does It Take for Phlox to Grow?

It generally takes about 2 to 3 weeks for phlox seeds to germinate and sprout. After that, it takes another 6 weeks for the seedlings to grow. However, the phlox growth varies on several factors, including the growing conditions.

How to Fertilize Phlox Seedlings?

You can start to fertilize the seedling once they have several leaves. It’s ideal to use a balanced fertilizer, such as a 10-10-10. You can dilute the fertilizer to half-strength to avoid over-fertilizing, which can damage the plants.

Apply the fertilizer around the base of the plants, taking care not to get it on the leaves or stems. Then water the seedlings well after fertilizing to help distribute the nutrients throughout the soil.

Remember to always follow the package instructions for application rates and frequency.

How Do You Keep Phlox From Dying?

Phlox is a hardy perennial plant that can live for many years if properly cared for. However, like all plants, phlox can sometimes succumb to disease, pests, or environmental stress. Here are some tips to help keep your phlox from dying:

  • Choose the right location
  • Water regularly, especially during dry spells
  • Fertilize in early spring and mid-summer
  • Use insecticidal soap to control infestations
  • Avoid overhead watering to prevent disease
  • Prune phlox after flowering


Follow the above steps for planting, watering, and caring for phlox seedlings. By doing so, you can enjoy the vibrant blooms and lovely scent of phlox all season long.

With a little patience, you can successfully learn how to start phlox from seed.