When To Plant Bulbs, According To Garden Experts

Crocuses, calla lilies, dahlias, irises, and tulips are some classic flowers that don't grow from seeds but from bulbs, an underground structure. Bulbs have short stems, and fleshy leaves and go through a period of dormancy. Growing bulbs requires planning because you don't plant them in the same season the flowers bloom. For example, if you want to enjoy beautiful tulips in the spring, you'll be planting them in the fall.  

We talked to gardening experts about when to plant bulbs. Here's what you need to know to successfully grow bulbs, including tips for a visually appealing bloom and how to care for your bulbs once they're in the ground.

When To Plant Bulbs

Spring and fall are the two seasons for planting. Bulbs that bloom in the spring are planted in the fall and bulbs that flower in the summer are planted in the spring, after the last frost. 

When To Plant Spring-Blooming Bulbs

Thinking ahead and careful planning is important if you want to enjoy beautiful blooms in your landscape. "The ideal planting window depends on your specific climate zone, but generally, you should plant bulbs from late September through November," explains Annette Thurmon, founder of Azure Farm and author of Simple Country Living. Common spring-blooming bulbs include crocuses, daffodils, hyacinths, irises, snowdrops and tulips. Planting needs to occur before the first frost. "It's best to wait until the soil is cool, about 6 to 8 weeks before the first hard frost," says Peggy Anne Montgomery, horticulturist and bulb expert for Flowerbulbs. "This window is crucial because it allows the bulbs to develop roots before winter arrives."  Each geographical region will vary so check your hardiness zone for frost dates.

Timing your planting is key to ensure nothing happens to the bulbs while in the ground. "Planting at the right time is one of the keys to the success of spring-flowering bulbs," explains Linda Vater, author of The Garden Journal and The Elegant and Edible Garden. "Early enough for root development and late enough to avoid early growth." 

What can happen if you plant too soon? "If planted too early, the warm temperatures could “cook” or rot the bulbs, or cause deformities in the flowers," says Montgomery. You also don't want to plant when the soil is too cold or frozen. "Planting after the ground is frozen is equally bad," adds Vater.

When To Plant Summer-Flowering Bulbs

Bulbs that flower in the summertime are planted after the last spring frost. This may be in early or late spring based on your geographical region. "Some common summer flowering bulbs include dahlias, gladiolus, lilies, cannas, begonias, and calla Lilies," says Thurmon. 

Live in a warmer geographical region? "In warmer climates (Zones 8-10), you can start planting summer bulbs as early as late March," says Thurmon. One way is to check the soil temperature to see if it's the right environment. "Make sure the soil temperature has warmed up to at least 55°F (13°C)," she says. If you live in a colder area, you'll likely need to wait for later spring. "In cooler climates (Zones 3-7), wait until the soil has warmed up and there is no longer a risk of frost," says Thurmon. "Typically, this is around mid-April to early May."  

Considerations Before Planting Bulbs

To ensure a successful bloom, pay attention to the quality and health of the bulbs and coordinate the right time to plant them. "Research your bulbs before planting," says Montgomery. "Different bulb varieties may have slightly different planting requirements." 

Choose Healthy Looking Bulbs

Look for high-quality bulbs that are firm when you hold them. Make sure the bulb looks healthy. "Inspect bulbs before buying for any signs of mold, rot, or softness," says Montgomery. 

Buy Only What You'll Plant

It may be easy to buy more bulbs than you have the time or space to plant when you see all the possibilities available. Knowing how many you need and can plant in your given space is important because bulbs need to be planted quickly. "Remember that bulbs are not meant to be out of the ground for very long periods, so it is best to plant bulbs in the same season you have bought them," says Thurmon. "This way, their nutrition reserves will be kept to an optimal and ensure healthy, beautiful plants."

How To Care for Bulbs

Caring for your bulbs is key to a vibrant flowering season. 

Sunlight

Bulbs grow best when they receive ample sunlight—a minimum of six hours per day. "Choose a location with the right amount of sunlight," says Thurmon. "Most bulbs prefer full sun to partial shade." 

Soil

Bulbs, just like the majority of plants, need well-draining soil. "Bulbs don't like soggy soil, so ensure proper drainage to prevent fungal diseases and rot," says Montgomery. If you plant directly in the ground, you may have clay, sandy or loamy soil. Loamy soil is ideal for bulbs. "Loamy soil is a balanced blend of clay, sand and silt—offering good drainage while retaining moisture and nutrients," explains Vater.

Water

After planting, water your bulbs. The amount you need to water varies based on your climate and soil type. According to Vater, "How and when to water will depend on the weather where you live. In the cooler months, you'll likely need to water less, especially if you live in a rainy area. "Water occasionally if the winter is very dry; and water after blooming as needed," she says. "This will depend on temperatures and high winds as well as amount of rainfall." 

Fertilizing

Fertilizing isn't necessary for bulbs because they are designed to have the nutrients they need. "The miracle of bulbs is that their ingenious packaging is pretty much all they need to bloom well in spring," says Vater. "I don’t typically fertilize at planting." 

There are exceptions for when you may want to use fertilizer. "If you are trying to perennialize bulbs and get them to come back year after year, you might consider fertilizing them with a specific granular bulb food as soon as they begin to emerge," says Vater. She likes to add a topdressing of compost instead of fertilizer. She notes that if you do use fertilizer, it could invite small animals. "Sometimes fertilizers, like blood and bone meal, may attract critters," she says

Mulch

After planting your bulbs, place a layer of mulch to protect the soil and help your bulbs thrive. "Applying a layer of mulch helps with soil temperature, moisture retention, and suppressing weeds," says Thurmon.

How To Avoid Pests From Getting To Your Bulbs

Bulbs can invite rodents and pests to the garden. Minimizing unwanted guests from snacking on your bulbs includes companion planting, physical barriers and natural repellents.

Companion planting

Growing plants that get along with each other is an easy and natural way to deter pests. For example, tulips and daffodils are a good pair and help keep unwanted animals away. "If planting spring bulbs like tulips, companion plant them next to daffodils, which are toxic to deer and rodents and will help keep them away," says Thurmon.

Natural Repellents

Using natural repellents to deter pests and unwanted animals from damaging bulbs is another option. "Sand or bits of gravel around the bulb area can deter pests due to their sharp nature," says Thurmon. Most people likely have a baking spice in their pantry that is an inexpensive solution. "Sprinkling cinnamon around the surface of the soil can also be very effective," says Thurmon. "Rats and mice detest the scent and will not come near."

Physical Barriers 

"Wire mesh or a hardware cloche or cloth can help cover the area the bulbs are in and prevent squirrels and other rodents from bothering them," says Thurmon. If you don't have much space, you may opt to plant bulbs in containers. Another benefit is this deters rodents from digging up your bulbs, says Thurmon. 

A bulb cage may be needed when unwanted animals are persistent in getting to your bulbs. "If you have no luck, you can also purchase bulb cages which are specifically designed to help protect the bulbs," she adds. 

Tips For Creating A Visually Appealing Display 

Having an idea of where and what you want to plant is key before you start planting bulbs. "Bulbs can grow in many ways, scattered, in a cluster, or as a beautiful border," says Thurmon. "Envision what you want to grow where so you can have a few seasons of flowers from one planting."

Choose Color Schemes

Consider the colors you love and want to see in your garden. "Mix pleasing colors together that will bloom in a beautiful parade of time over spring," says Vater. "Choose complementary or contrasting colors for a vibrant and striking display." Thurmon loves grouping similar hues together. "When it comes to bulbs like tulips, I always like to plant them close together by color scheme to ensure a showstopping display of colors in the spring," she says. 

Consider Blooming Times

Most experts love to have a variety of hues, along with blooming times so there's always a spectacular show of colors in the garden. "Plant a combination of early, mid, and late-season bloomers to extend the blooming season," says Thurmon. Think about texture and how many flowers you want to grow, too.  "You can never be too rich or too thin, or plant too many bulbs if you have the room," says Vater. 

Wondering if you should plant bulbs together or separately? "Plant bulbs in groups or clusters for a more impactful display [and] scatter smaller bulbs like crocuses for a naturalized effect," says Vater. You also want to think about height and dimension when choosing locations. "Plant taller bulbs towards the back and shorter ones in front for a tiered effect," says Montgomery.