Fall Is the Time to Plant Spring BulbsOctober, 2019
Story and photo By Emma Erler
UNH Extension Education Center Program Coordinator
Want to see a beautiful spring out your window? Then fall is the time to start planting bulb flowers.
Planting a few new daffodils or tulips is an annual autumn tradition for many gardeners. After a long winter there is nothing more refreshing than seeing the first spring flowering bulbs emerge from the soil.
Almost any garden can benefit from the addition of a few bulbs. Spring bloomers bring a welcome pop of color to the garden early in the season. Better yet, their foliage dies back by early to mid-summer, making way for perennials that emerge later, or providing spaces to replant with summer annuals.
Choosing Which Bulbs to Plant
First and foremost, know your growing zone before choosing which bulbs to plant. Bulb catalogs offer dozens of options, but not all spring flowering bulbs will survive in New Hampshire.
Additionally, make sure that your garden gets enough sun to support healthy bulb growth. Early blooming bulbs like crocuses, snowdrops and squill can tolerate some shade, but daffodils need full sun exposure to bloom year after year.
Order bulbs early in the season for the best selection. When selecting bulbs, choose the largest ones of a variety that you can, as there is a direct correlation between the size of a bulb and size of flowers produced by that bulb.
In terms of flower quality, it often pays to spend a little more on high-quality bulbs rather than picking them up at a discount store. Also be sure to note the condition of bulbs before purchase. Avoid bulbs that show any signs of decay or damage, often evidenced by mold on the outer surface.
If you’re tired of classic standbys like daffodils, try planting some more unusual species. Grecian wildflower (Anemone blanda) produces daisy-like flowers above ferny foliage in early spring.
Camass (Camassia leichtlinii) grows spectacular spikes of blue flowers amid upright, grassy foliage, and winter aconite (Eranthis hyemalis) forms a carpet of yellow buttercup-like flowers in late winter. For those interested in native plants, try spring beauty (Claytonia virginica), rue anemone (Anemonella thalictroides) or bloodroot (Sanguinaria canadensis).
When to Plant
Wait to plant spring flowering bulbs until the soil temperature drops below 60 degrees Fahrenheit, which can be measured with a soil thermometer. If bulbs are planted when temperatures are warm, they may come up too soon and their foliage may be susceptible to winter damage.
Ideally, bulbs need a little time to establish their root systems before the winter. Bulbs will grow roots until the soil reaches 40 degrees Fahrenheit, at which point growth is halted.
Make sure to gauge the soil temperature in the area you intend to plant your bulbs. Soil near foundations with a southern or western exposure will cool down much slower than soil in low-lying or shady areas.
Small bulbs such as crocuses and grape hyacinths should be planted as soon as possible. They are more likely to dry out and will freeze earlier since they are planted shallowly.
Larger bulbs such as daffodils and tulips can be planted later. If you’re not ready to plant yet, tuck the bulbs into a cool, dark and dry space such as the refrigerator or root cellar.
How to Plant
In order to thrive, bulbs require moist, well-drained soils. If your soil isn’t perfect, you might consider amending it before planting. The drainage of clay soils can be improved with the addition of organic matter, and the water holding capacity of sandy soils can be enhanced by incorporating ample amounts of compost.
Planting bulbs is easy, as long as you follow a few, simple guidelines. First, make sure to plant with the growing tip pointed up and the root scars down. This can be more difficult than it seems on the surface, depending on the type of bulb. When in doubt, plant bulbs on their sides to give them a greater chance of sprouting.
Planting depths vary, but generally, most bulbs, corms and tubers should be planted two to three times as deep as the bulb is tall. Large bulbs like daffodils may be planted 6 to 8 inches deep, while small bulbs like snow drops should be planted only 3 to 4 inches deep, measuring from the bottom of the bulb. Many garden trowels have inch markers on them, but if yours does not, a ruler will do.
How far to space bulbs is mainly a question of aesthetics. Bulbs spaced closely together will have a lusher look in their first season. However, leaving a little extra space will give bulbs the room they need to grow and spread over time. Aim to space large bulbs at least 6 to 8 inches apart and small ones 4 to 5 inches from one another.
Healthy, mature bulbs contain all the nutrients they need for the current season’s growth and bloom. After flowering, bulbs can benefit from the application of a slow release fertilizer or top dressing of compost.
Added nutrients will help replenish the bulb and ensure re-flowering the following spring. Lightly work fertilizer into the soil so that it will reach the roots.
For years, many gardeners have been told that bone meal should be added to the soil when planting because bulbs need phosphorus for root growth. However, most New Hampshire garden soils already have more than enough phosphorus to cover plant needs, and bone meal can attract rodents that may dig bulbs up.
The presence of wildlife in your garden is an important consideration when deciding which bulbs to plant. Chipmunks, squirrels, voles, mice and deer are very good at locating and quickly devouring bulbs that have been recently planted.
Although bulbs are not usually a preferred food, they are frequently attacked when other resources are scarce in the late fall and winter months. Certain types of bulbs are known to be especially appealing to wildlife.
Freshly planted tulips, and to a lesser extent, crocus are regularly devoured by voles, chipmunks and deer. The only guaranteed way of preventing this is to exclude wildlife.
Use half-inch galvanized hardware cloth (wire mesh) to create cages to protect the bulbs. Place the bulbs inside of the cages with the root end down and bury the entire cage at the proper planting depth.
When done properly, rodents will be unable to access the bulbs. Repellents can also be effective if they are applied to the soil at the planting site, but they must be reapplied frequently, especially after every rain.
The easiest way to ensure that wildlife will leave your new plantings alone is to choose bulbs that wildlife ignore. While tulips and crocus are often quick to disappear, daffodils, snow drops, glory-of-the-snow, Siberian squill, grape hyacinth and allium are usually safe without any added protection. However, even though wildlife species may not eat those bulbs, they might still dig them up.
When done properly, planting spring flowering bulbs can be an enjoyable and rewarding activity. As long as you thoughtfully choose which bulbs to plant and select a good location in the garden to plant them, you’re sure to be rewarded with blooms for many seasons to come.
Got questions? UNH Cooperative Extension Education Center’s Info Line offers practical help finding answers for your lawn and garden questions. Call toll free at 877-398-4769, Monday through Friday, 9 a.m.to 2 p.m., or email email@example.com.