September is an ideal time to plant perennials in many gardens. For most of us, this is the end of summer and the start of fall. We can expect plenty of warm days still, but the cold days and the first frost and freeze aren’t too far away. The cooler days of September are easy on newly-planted perennials, and gardeners, too!
Another good reason to plant spring-blooming perennial flowers now is to help them establish roots. Planting in September gives them time to grow strong roots before the ground freezes. If you plant them in spring, they’ll put more energy into blooming than into growing roots.
With this in mind, here are some of our favorite perennials with spring flowers that you can and should plant now. Before planting, check that the varieties are compatible with your USDA zone and soil type.
1. Allium
Allium is a genus of flowering plants that includes onions and garlic. When talking about flowering perennials, allium refers to ornamental onion – a tall, spring and early summer flower. Growing alliums is a great option in USDA zones 4 through 10. They can grow up to 4 feet (1.2m) tall and bloom with unique, round flower heads composed of dozens of small, star-shaped blossoms.
For a real showstopper, try Breck's giant allium dormant bulb mixture, available at Walmart, which features impressive blooms measuring up to 5 inches (12.5cm) in diameter.
Plant allium bulbs in slightly acidic soil that drains very well and in full sun. Allium will tolerate a little shade, but does best in full sunlight. As long as it’s raining regularly, alliums don’t need much additional water. Fertilize in late summer if your soil is poor, using a specialist bulb fertilizer such as Espoma Organic Bulb-Tone, available on Amazon.
2. Penstemon
Penstemon (Penstemon spp.), also known as beardtongue, blooms in spring and summer on stalks up to 5 feet (1.5m) tall. The individual flowers are small and similar to those of snapdragons, to which they are related. You can find them in nearly every shade, including blue, purple, white, pink, red, and yellow.
Grow penstemon in USDA zones 3 through 8 in soil that drains very well and in full sunlight. Too much shade will cause the tall flower spikes to droop. Penstemon needs just an inch of water per week and one application of fertilizer in the fall.
It's easy to propagate penstemons from cuttings at this time of year, but you can also start them from seed. Everwilde Farms sells a good range of penstemon seeds on Amazon.
3. Daffodils
Daffodils are among the most iconic of spring flowers and grow from bulbs planted in the fall. Daffodils belong to the Narcissus genus. They grow to no more than about 30 inches (0.8m) tall and make great edges and borders. They also work well in naturalized plantings.
You can find different varieties of daffodils in classic yellow, but also in white or peach, and with double petals and multiple colors. These best-selling Garden State Bulb All-In-One Mixed Daffodil Flower Bulbs from Walmart are a great place to start.
Daffodils are perennial and will return and spread each year. If you want a more immediate impact in the spring, plant the bulbs close together, about 5 inches (12.5cm) apart. Plant daffodil bulbs in full sun and in neutral or slightly acidic soil that drains well and is fertile.
4. Bearded Iris
For pretty spring flowers, it’s hard to beat the tall, elegant iris. Bearded irises grow up to about 4 feet (1.2m) tall and bloom in a range of colors depending on variety: purple, yellow, orange, red, white, pink, and bicolor. You can grow bearded irises in USDA zones 3 through 9.
Plant bearded iris in a sunny spot and in soil that drains well. Irises don’t tolerate clay soils but grow just fine in sandy or even gravelly soil. Many varieties of bearded iris bloom in spring, including ‘Maid of Orange,’ ‘Clarence,’ ‘Hello Darkness,’ and ‘Rare Treat.’ This Easy to Grow Bearded Iris Colorful Crop Mix of 9 bulbs from Walmart offers a lovely combination for a first attempt at iris growing.
5. Crocus
Crocus is another classic spring bulb that should be planted in the fall. Like daffodils, crocuses are perennial and will spread each year. You can use crocuses in beds or along edges, but consider planting them in a meadow or even in your lawn. They’ll provide natural early spring color when they emerge before most other flowers and then fade back to let the grass take over.
Crocuses only grow about 6 inches (15cm) tall and are suitable for USDA zones 3 through 8. Plant them in areas that get full sun. The soil type doesn’t matter too much, but it should drain well, or the bulbs will rot.
This Willard & May mixed giant crocus bulb collection, available via Amazon, offers good value and a charming color mix.
6. Peonies
Peonies (Paeonia officinalis) are old garden favorites. Once established, they require minimal care and can grow in a wide range of gardens, from USDA zones 3 through 9. Peonies are perennials that typically grow 3 feet (0.9 m) tall and a little wider. They bloom in spring and early summer with spectacular, large, and heavy blooms in shades of pink, white, and red.
Burpee sells a stunning range of peony roots ready to plant now.
Plant peonies in the fall, but be aware that they are fussy about being transplanted. Don’t be alarmed if they don’t bloom the following year. Plant peonies in a spot with full sun and soil that drains well. Mix compost into the soil, and they won’t need fertilizer later.
7. Hellebore
One of the earliest of all perennial bloomers, hellebore flowers in spring, or in warmer climates, in winter. This latter habit is why it is also called the Lenten rose. Hellebore is prized for its early flowers in shades of white, yellow, purple, and pink. You can even find varieties, like ‘Dark and Handsome', available at Burpee, with nearly black flowers. They also have attractive foliage that makes a nice groundcover when the plants are not in bloom.
Plant hellebores in fall in USDA zones 3 through 9 and expect them to get no taller than two feet (0.6m). They grow very well in partial or even deep shade. Full sun is too much for hellebores. The soil should be rich in organic matter and drain very well.
