Whether for cut flowers or to add a pop of color, bulbs are an easy, low-maintenance garden addition. Flowering bulbs come in a wide variety of shapes, sizes and colors; fit into most landscapes; and provide seasonal color.
Fall is the best time to plant bulbs for spring blooms and can be planted into existing landscapes. Bulbs fill the gap between ground cover and shrubs with fragrance and beauty. “If you can stick your finger in the ground, there is room for a bulb,” said Ruth E. Wolfe, UCCE Master Gardener emeritus, retired landscape designer and bulb specialist.
Bulbs are a unique plant organ because their underground structures store reserves of food and water.
“Bulbs are like armored cars. They have everything they need to grow with them,” Wolfe said. Another bulb trait is that most propagate asexually, which means without pollination.
There are five bulb types:
The first, true bulbs, are identified by rings that appear when sliced. Common flowering true bulbs are tulips, daffodils, hyacinths, amaryllis and Dutch iris. Edible bulbs are onion and garlic.
A corm stores its food in its stem. It looks similar to a true bulb but has a solid interior. The exterior is scalelike and <FZ,1,0,39>sometimes rough. Flowering corms include gladiolus, crocus, freesia and watsonia. Water chestnuts are edible corms.
Tubers also store their food in underground stems but have multiple “eyes” or buds from which growth occurs. Tubers can be planted whole or cut into pieces with at least one eye per piece. Tuberous begonias, cyclamen and anemones are flowering tubers, and potatoes and yams are edible tubers.
Tuberous roots store resources in their roots and taper at both ends. They grow in clusters, which are separated for propagation. Flowering tuberous roots are dahlias, agapanthus and ranunculus. Sweet potatoes are an edible tuberous root.
Rhizomes grow horizontally with elongated underground stems. To propagate, cut into smaller pieces with each piece having at least one lateral bud or “eye.” Flowering rhizomes are bearded iris, cannas and calla lilies. Some rhizomes, like Bermuda grass and mint, can be invasive and spread easily.
Select bulbs that are firm and uniform in color. Dark spots might be symptoms or signs of mold. Avoid bulbs that are shriveled, lightweight or have soft spots. Bulbs store their own nutrients, so larger bulbs produce better flowers.
<bsp-module data-state="{"cms.site.owner":{"_ref":"00000163-26ee-da3a-a1ff-6eefbc380000","_type":"ae3387cc-b875-31b7-b82d-63fd8d758c20"},"cms.content.publishDate":1631320279604,"cms.content.publish":{"_ref":"00000169-b65f-d577-abfb-b7df37250000","_type":"6aa69ae1-35be-30dc-87e9-410da9e1cdcc"},"cms.content.updateDate":1631320279604,"cms.content.update":{"_ref":"00000169-b65f-d577-abfb-b7df37250000","_type":"6aa69ae1-35be-30dc-87e9-410da9e1cdcc"},"module":{"title":"Fall Garden Tour","description":"Be inspired by 15 local gardens in the Master Gardener Association of San Diego County’s annual Fall Garden Tour. Early registration highly recommended.","items":[{"text":"When: 9 a.m. to 4 p.m., Sept. 18
Where: North coastal area of Carlsbad","_id":"0000017b-d243-d33b-a77b-fee7241e0002","_type":"2d8cea80-ec5b-3076-9c3c-39086f44ad66"}],"cta":{"text":"Details: mastergardenersd.org/fall-garden-tour/","link":{"target":"NEW","attributes":[],"url":"https://www.mastergardenersd.org/fall-garden-tour/","_id":"0000017b-d242-ded3-a77b-faef399b0002","_type":"ff658216-e70f-39d0-b660-bdfe57a5599a"},"_id":"0000017b-d242-ded3-a77b-faef39980000","_type":"f4dcfa63-dc48-3426-a5ca-724cf1d776fe"},"theme.00000166-300c-ddc8-a177-f44f8d870000.:infobox:Infobox.hbs.imageTransformation":null,"theme.00000166-300c-ddc8-a177-f44f8d870000.:infobox:Infobox.hbs.leftAlignTitle":false,"theme.00000166-300c-ddc8-a177-f44f8d870000.:infobox:Infobox.hbs.leftAlignDescription":false,"theme.00000166-300c-ddc8-a177-f44f8d870000.:infobox:Infobox.hbs.leftAlignLinks":false,"theme.00000166-300c-ddc8-a177-f44f8d870000.:infobox:Infobox.hbs._template":null,"_id":"0000017b-d242-d5bb-a17f-dbfb29ad000c","_type":"1bd71488-cfff-3e76-bbca-93f270e46b6e"},"theme.00000166-300c-ddc8-a177-f44f8d870000.:core:enhancement:Enhancement.hbs.alignment":"align-right","theme.00000166-300c-ddc8-a177-f44f8d870000.:core:enhancement:Enhancement.hbs._template":null,"_id":"0000017b-d242-d5bb-a17f-dbfb29970000","_type":"c5b60bfe-fc18-3e1d-bd70-75608e803f66"}”>Visit 15 local gardens and be inspired in the Master Gardener Association of San Diego County’s annual Fall Garden Tour. Early registration highly recommended.
Bulbs grow best in loose, well draining soil with a soil temperature below 70 degrees. To prepare the soil, remove all weeds and debris and work in compost. Dig holes to the recommended depth. If the depth is unknown, a rule of thumb is to plant the bulbs at a depth three times the height of the bulb. Use a bulb trowel or bulb planter, marked with inches, to help in digging to the correct depth. Insert the bulb pointy end up or roots down. Cover with soil and water until moist. After blooming, deadhead and retain the green shoots until brown, then remove. Keeping the shoots on the bulb adds food into the bulb’s storage system, which will help next year’s bloom. Fertilization is not needed.
For fall bulb planting in San Diego, Wolfe suggest several varieties of Narcissus such as ‘Avalanche,’ ‘Ice Follies’ or ‘Tahiti.’ Each blooms during a different month, providing a long season of color. She also recommends experimenting.
“Try something that is new to you. You just might like it,” she said. Some suggestions are babiana, a striking and adaptable bulb, and watsonia, also known as ‘Bugle Lily.’
Another bulb to consider is ranunculus. This tuberous root produces the flowers for the beautiful ribbons of color at The Flower Fields at Carlsbad Ranch. San Diego’s Mediterranean climate is ideal for growing ranunculus, and October to January is the best time to plant. Kick-start the growing season by refrigerating the bulbs for two weeks prior to planting, then plant pointy ends down. If you have many bulbs, plant every two weeks for a long season of blooms. Different from other bulbs, remove the leaves after flowering, do not water, and let the bulbs remain in the soil. Dig them up in July and store in a low-humidity location.
Bulbs are relatively pest-free. Snails are primary pests and can be managed by picking them up, putting them into a closed container and disposing of it in the trash. Vertebrate pests also cause bulb damage. They are best managed by setting up barriers such as covering the planting site with hardware cloth.
The planning and planting done in the fall will give rewards with beauty and fragrance in the spring. And for the impatient, the good news: There are also fall-blooming bulbs to provide autumn color and scent.
Bulb design tips
Wolfe offers the following suggestions for choosing and planning where to plant your flowering bulbs:
Know your bulbs. Match them to plants with similar water, sun and soil needs, and bloom cycle. A good online resource is Easy to Grow Bulbs in Oceanside.
Plant in layers. Bulbs are planted at different depths. Plant the deepest bulbs first and then others at shallower depths. This gives a lush multilayered bloom.
Begin at the edge. Plant an impactful border. Select low-height bulbs that will grab the eye and lead the viewer to the rest of the garden.
Odds are best. Group bulbs in odd numbers and plant randomly, not in a row.
Stagger bloom cycles. Plant early blooming in back, late blooming in front and mid-blooming in the middle.
Under-plant. Plant bulbs into existing landscape by tucking under plants, being cautious to not disturb the roots.
Bay has been a Master Gardener since 2012. She is an instructor in the Beginning Vegetable Gardening workshops, which teach new gardeners how to grow a healthy and bountiful vegetables.
The Master Gardener Association of San Diego County is involved in a variety of outreach programs. Get free home gardening advice by phone on the Master Gardener Hotline, (858) 822-6910, or email at [email protected].
