Grape hyacinths are my favorite spring bulbs because of their unusual flowers. As their name implies, the flowers look just like a cluster of grapes. I call them “escape artists” because they multiply rapidly and spring up in unlikely places like my lawn.
What are Grape Hyacinths?
Grape hyacinths (Muscari armeniacum) are perennial bulbs that are related to asparagus. They are native to Europe and Asia and hardy in zones 3–9.
Grape hyacinths are small, only growing 6–9 inches tall and 3–6 inches wide. Their small stature makes them a good choice for borders or along walkways. They are also attractive in rock gardens.
Their leaves are blades that look a lot like grass. They grow directly out of the bulb rather than on a stem. They appear in the early spring and persist until after the plants have finished blooming when they die. Unlike other spring blooming bulbs, the foliage appears again in late summer or early fall. It is important to leave the foliage until it dies because it is storing food in the bulb for next year’s growth. Many gardeners take advantage of this second flush of foliage. They plant grape hyacinths bulbs to mark where their other spring bulbs are planted so they don’t accidentally dig them up when they are planting perennials in the fall.
Grape hyacinth flowers grow on a stem that is 4–8 inches tall. The cluster of grapes effect is from the 20–40 flowers tightly packed on the top of the stem. The flowers can be blue, pink or white. They open starting from the bottom of the cluster to the top. Bloom time is April–May, depending on your growing zone. The flowers last 3–4 weeks.
The flowers are followed by green seed pods that are composed of three chambers, each filled with seeds. If you leave these seed pods on your plants until they ripen and release their seeds, you will have new grape hyacinth plants the following spring. It is best to remove the seed pods as soon as they appear so that the plants will concentrate on producing food for their bulbs for next year instead of unneeded seeds.
How to Plant Grape Hyacinth Bulbs
Choose a spot in your garden that gets full to partial sun. Grape hyacinths grow best in full sun, but their flowers last longer in partial shade. When choosing a planting area for your bulbs, remember that many areas are sunny in the spring before the trees leaf out. These are good spots for your grape hyacinths because the bulbs will finish blooming before the trees develop their leaves and create shade.
The bulbs grow best in well-drained soil. Avoid areas with a lot of clay or that are frequently wet. Soil that is too wet will result in rotted bulbs. Grape hyacinths are not particular about soil pH. Keep your bulbs well-watered in the spring when they are growing and blooming. Once they have finished, you can allow the soil to dry out a little to avoid rotting the dormant bulbs.
The bulbs should be planted in the fall after the soil cools down. For my zone 6 New Jersey garden, that is the end of October at the earliest. If the soil is too warm when you plant your bulbs, they will begin to sprout. You want your bulbs to remain dormant until the soil warms in the spring. You can plant your bulbs any time up until the soil freezes whenever that is in your area.
In zones 8 through 10, the winters do not get cold enough to provide the chill that the bulbs need. Gardeners in those zones need to fool their bulbs into thinking that they have experienced winter by chilling them in their refrigerators for 10 weeks before planting them in December or January.
Plant your bulbs 3 inches deep and 3 inches apart. Because the plants and flowers are so tiny, it is best to plant them in groups of five. Even better are large drifts or groupings of them. That’s a lot of holes to dig so what I do is rather than digging all those individual holes, I get out my shovel and dig one big hole, 3 inches deep and as large as I need to plant all of my bulbs.
I sprinkle ¼ cup of bone meal per 100 square feet in the bottom of the hole and then place each bulb along the bottom of the hole where I want it to grow. Bulbs should be planted with the pointed end facing up. That is where the plant will grow from in the spring.
Be careful when you are shoveling the soil back into the hole to not knock over the bulbs. I usually use my trowel, rather than my shovel, to refill the hole. It takes longer, but it ensures that the bulbs are not disturbed.
Each spring when your grape hyacinths appear, sprinkle another ¼ cup of bone meal per 100 square feet. No other fertilizer is required.
How to Divide Grape Hyacinths
Grape hyacinths multiply every year. The bulbs should be divided every three years. You can do this in the late summer when they are growing their second flush of leaves. Carefully dig up the bulbs and divide them by gently twisting them apart. Discard any bulbs that are shriveled or rotted. Replant the healthy bulbs 3 inches deep and 3 inches apart.
How to Force Grape Hyacinth Bulbs Indoors in the Winter
Grape hyacinths can be forced to bloom indoors like narcissus. You should plan on 22 to 24 weeks to bloom time.
Because the bulbs need a 10-week period of cold to initiate growth, place them in your refrigerator for that time period. At the end of ten weeks, you can remove them and plant them in a container that is at least 6 inches deep and 6 inches wide.
Unlike in your garden, you will want to plant your bulbs 1 inch apart with the pointy end facing up and exposed above the soil. Place the container in a cool, dark place for another ten weeks. At this point, you should have leaves that are about 2 inches long. You can then move the container to a sunny spot. The plants should bloom in 2 to 3 weeks.
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