Phlox Planting Guide

The phlox clan is a large and diverse group. These phlox are commonly known as "Garden Phlox" and "Summer Phlox" and are the tall, fragrant beauties that add sparkle to gradens in the northern two thirds of the country from mid summer into earl fall. Attracting butterflies and emitting a soft sweet scent, these blooms are essential landscape elements. Summer phlox are often referred to as garden workhorses becase they are remarkably useful, durable and dependable.

Choosing a Site for Summer Phlox

Summer phlox are happiest with sunny sites with good air circulation. Don't tuck them back in a corner, instead go ahead and place them in that sun splashed spot where there's always a bit of a breeze.  Phlox are more tolerant of clay soils than are most perennials plants.

Soil Prep

Light to moderate feeders, phlox grow well in average, well-drained soil and don’t require rich, perfect loam. Compost, dug in when planting or added as a top dressing later, provides a welcome supply of nutrients. Keep in mind that composts' NPK (nitrogen, phosphorus, potassium) ratio often varies greatly product to product. Don't assume that adding more is better.

When to Plant Phlox

Plant outdoors when frost danger has past. Phlox are hardy perennials and can take freezing without ill effects once they are established but are susceptible to frost damage prior to settling in. 

How to Plant Dormant Bareroot Phlox

Your phlox plants are shipped bareroot, in a dormant state. Dormancy means the plant is not in actively growing; it’s been held in a cool, dark setting similar to winter garden conditions and is “sleeping”. The bareroot term means that the soil has been washed from the roots; there is no risk of introducing any soil-borne diseases into your garden. Plus, the plants are lighter and cleaner to ship. When you plant your phlox, adding light and moisture, they’ll wake up. Roots start growing in a few days and top growth will be visible in 1-3 weeks. 

Dig a hole a bit bigger than the root mass and fan out the roots in your planting hole. Place the crown (area from which leaves will sprout) at or just below below soil level. Refill around plant with soil, tap down to eliminate any big air pockets and water well.

In the garden, space your plants so they have enough room to grow without crowding, typically 18-24” between plants. Over time, phlox plants develop into sizeable clumps so give them room to grow.

During the Growing Season

Phlox require little care during the growing season. During their first season, while they are settling in, make sure they receive 1-2” of water, from rain or irrigation, per week. From their second season on, they’ll be fine with about the same or a little less. Feel free to snip flowers for bouquets. This won’t hurt the plants. Or leave the flowers to attract butterflies and hummingbirds.

Insider Tips

  1. Deer and rabbits tend to avoid astilbes. If hungry deer and/or rabbits are a problem in your area, astilbes could be the perfect solution.
  2. Summer phlox are well suited to climates in New England, The midatlantic, Midwest and Northwest. They don't love the heat and humidity of the deep South.
  3. Where happy, Garden phlox readily grow into sizeable clumps. Divide every 3 to 4 years by lifting in the spring when you see new growth and pulling/cutting apart sections. Replant the new phlox at soil level and water to settle in. Or share with friends!
shop phlox
shop phlox

Success Snapshot

Light: Sun to mostly sun

Soil: Fertile and well drained

Depth: Plant clumps at ground level

Water: Average moisture

Uses: Landscape beds and cutting gardens

Tip: Grow phlox for a generous supply of fragrant cut flowers

GUIDE: Phlox Planting Guide

They Start Out Looking Like This: