Fall Planting Tips: How Many Bulbs Per Square Foot?

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As with most things gardening, there are no hard and fast rules for how closely to space spring-blooming bulbs such as tulips, daffodils and alliums. But you can be sure of one thing: they always look best planted generously. Spring bulbs have far more impact when you see them as a group rather than as individuals blossoms.

Bulb spacing has little to no impact on performance. This is because fall-planted bulbs already contain everything needed to produce beautiful spring flowers. All they require is well-drained soil, enough room to develop a good root system, adequate moisture and the right soil temperature.

How many bulbs you plant is a balance between your budget and your goals. When flower farmers plant bulbs, they are growing them as annuals and want to harvest as many stems as possible from a given amount of space. The bulbs are packed so tightly that they are almost touching each other. Home gardeners are usually driven by aesthetics rather than productivity. We are striving for the biggest, most visually pleasing display we can afford.

General Tips for Spacing Fall-Planted Bulbs

If you compare bulb spacing recommendations, you'll find they vary widely. Some say to plant tulips at 5 bulbs per square foot. Though planting the bulbs this sparsely will save money, you may be disappointed by the show. For a more impressive display, you'll want to increase the density to 9 or even 12 tulips per square foot.

Note that most recommendations assume you are planting an area with nothing but bulbs. In practice, gardeners usually need to work bulbs in and around other plants. When estimating how many bulbs you'll need, be sure to make adjustments for areas that are already occupied by other plants.

Annual vs Perennial Bulbs

Bulbs that are grown as annuals, such as tulips and hyacinths, are usually planted quite close together. When the flowers are fully open, you want each one to have its own air space, but not much more than that. Aim for the blossoms to be just a few inches apart.

Daffodils call for a slightly different approach. Since they will multiply over time, it’s good to start them out with a little more room. Give large daffodil bulbs about 5” of space between each bulb; for smaller bulbs, you can allow just 3” between bulbs. Your daffodil planting may be a little sparse the first spring, but after a year or two, the bulbs will double and triple to completely fill the space.

Small bulbs such as muscari, crocus, snowdrops, scilla and chionodoxa also need room to multiply. These bulbs look best planted in groups with irregular spacing both within and between the groups. Dig out a small planting area and place 7 to 12 bulbs so the distance between them varies from 1" to 3". Then move a foot away and plant another group of bulbs.

Estimating Quantities

To estimate the number of bulbs you’ll need for a given area, start with a rough estimate of the square footage. For example, if you are planting along a fence or the front edge of a woodland area, multiply the depth of the area by its length. If you want to fill a 3x8 garden bed with tulips multiply 3x8 to get the amount of space in the planting area: 24 square feet.

Once you have the total square footage, multiply that by the number of bulbs per square foot, which will be different for each type of bulb. Remember to think about areas that are already filled with other plants and adjust accordingly. A 12" x 12" square of paper may make it easier to visualize the bulb counts. Though bulb spacing is really a judgement call, here are some recommendations to get you started.