Fall Bulb Planting: How to Get a Spring Garden You'll Brag About

Why fall is the moment

Spring-blooming bulbs such as tulips, daffodils, crocuses, and hyacinths are small packages of stored energy, and they need a stretch of cold weather to trigger flowering. Planting in fall gives their roots time to establish in cooling soil, then lets winter chill do its job. Skip the cold period and you get weak stems, stunted flowers, or nothing at all.

Here in Portland, where our winters are mild and wet, we plant most bulbs from mid-October through late November. The rule of thumb that works almost anywhere is to plant when nighttime temperatures have settled into the 40s and 50s °F and the soil at 4 inches down has cooled to roughly 55°F or below. Plant too early in warm soil and bulbs can sprout leaves prematurely; plant too late, and you risk frozen ground, but you can still get bulbs in the soil until it freezes solid.

Choosing bulbs and picking a site

Buy bulbs that feel firm and heavy for their size, with no soft spots, mold, or shriveled skin. Larger bulbs generally mean bigger blooms. Plant them within a week or two of buying, and if you must wait, store them somewhere cool, dry, and airy at about 60°F rather than in a plastic bag.

Most spring bulbs want full sun in spring, which in practice means a spot that gets at least 6 hours of light before deciduous trees leaf out. Drainage matters more than anything else: bulbs sitting in soggy soil rot before they bloom. If your soil is heavy clay, dig in a few inches of compost or grit, or grow bulbs in raised beds and deep containers filled with Greenhouse Potting Mix. Avoid low spots where water pools after a rain.

Depth, spacing, and the pointy-end-up rule

A reliable guideline is to plant each bulb at a depth of about three times its height. That means large tulips and daffodils go 6 to 8 inches deep, hyacinths about 6 inches, and small bulbs like crocuses and grape hyacinths about 3 to 4 inches. Measure from the base of the bulb, not the tip. Set them pointy end up, root side down, and if you cannot tell which end is which, plant the bulb on its side; it will sort itself out.

For spacing, put large bulbs 4 to 6 inches apart and small ones 2 to 3 inches apart. Bulbs look best in clusters of 7 to 12 rather than single file lines, so dig one wide hole and place the whole group in it. Backfill, firm the soil gently, and water well to settle it, even if rain is in the forecast. One deep soak of about an inch of water starts root growth right away.

Layering for color from March to May

The 'lasagna' method fits several layers of bulbs into a single pot or bed. In a 16-inch container, start with a couple of inches of potting mix, then add a layer of late-blooming tulips at about 8 inches deep. Cover with 2 inches of mix, add daffodils, cover again, and top with a layer of crocuses or grape hyacinths just 3 inches below the surface. As each layer emerges in succession, you get continuous color from late winter through mid-spring.

Pair bulbs with perennials that will cover their fading foliage later. Coneflowers, catmint, and Blue Fescue grasses leaf out in late spring just as bulb leaves turn yellow, so the bed always looks intentional. Set a few Garden Labels and Copper Plant Markers where you planted so you don't accidentally dig into them in March.

Winter protection and pests

Squirrels and voles love bulbs, especially tulips and crocuses. If they are a problem, lay a piece of chicken wire flat over the planting area and cover it with soil or mulch, or plant deer- and rodent-resistant varieties like daffodils, alliums, and fritillaria, which are toxic or distasteful to critters. Spreading 2 to 3 inches of shredded bark mulch after the first hard frost keeps soil temperature steady and suppresses weeds.

Container bulbs are more exposed than in-ground ones, since roots in a pot lack the insulation of the earth. In areas that regularly dip below 15°F, move pots against a sheltered wall, wrap them in burlap, or set them in an unheated garage, watering lightly about once a month so the mix never turns bone dry.

After the bloom

When flowers fade, snip off the spent bloom to prevent seed production, but leave the green foliage alone for at least 6 weeks. Leaves are recharging the bulb for next year, and cutting them early is why many tulips shrink or vanish after a season. Once the foliage has yellowed and flopped over, you can remove it cleanly.

A light feeding at planting and again when shoots emerge helps bulbs perform for years. We like a diluted Liquid Seaweed Plant Food every couple of weeks while the leaves are green. With a little planning in October, you will be enjoying flowers by early March and celebrating well into May.