Planting Spring Bulbs: Timing, Depth and Keeping Deer Off Them

Every daffodil, tulip, crocus and allium you see in April was planted in the fall. Spring bulbs need a long cold spell to set their flower, so the window to get them in the ground is now — roughly from the time nights turn cool until the ground freezes. It is one of the highest-return jobs in the yard: an hour with a trowel in October, and a bed that comes back every spring for years.

It is also a job people get wrong in three predictable ways: planting too early, planting too shallow, and choosing tulips in a yard full of deer. Here’s how to get all three right.

When to plant: cool soil, not a calendar date

Bulbs want to go in when the soil has cooled to about 55°F (13°C) — usually once nighttime temperatures are reliably in the 40s and 50s. Plant into warm soil and the bulbs may sprout leaves this fall or rot; wait too long and they don’t have time to grow roots before the freeze. In most of the country that gives you a generous window of six to eight weeks.

Not sure of your zone? Every deer-resistant plant page on Clearly is sorted by zone, and the plant finder lets you filter to yours. If the bulbs arrive before the soil is ready, store them in a cool, dry, dark spot — a garage shelf or a paper bag in the basement — never in a sealed plastic bag, and never near ripening apples or bananas, whose ethylene gas can kill the flower inside the bulb.

How deep, how far apart, and which end is up

The rule that covers nearly everything: plant a bulb about three times as deep as it is tall, measured to the bottom of the bulb. A 2-inch tulip or daffodil bulb goes in a 6-inch hole; a small crocus or grape hyacinth goes 3 to 4 inches down. Too shallow is the most common mistake — shallow bulbs heave out of the ground in freeze-thaw cycles, dry out, and are the easiest for squirrels to find. Err deeper, especially in sandy soil.

• Pointed end up, roots down. If you can’t tell (alliums and anemones are ambiguous), plant it on its side — the shoot will find its way.
• Space large bulbs 4–6 inches apart, small bulbs 2–3 inches. For a natural look, plant in loose groups of odd numbers (7, 11, 15) rather than single-file rows.
• Dig a bed, not a hole per bulb. For anything more than a dozen, excavate the whole area to depth, set the bulbs, and backfill once. It’s faster and the spacing comes out right.
• Drainage is the one thing bulbs can’t forgive. A spot that puddles in spring will rot them. If your soil is heavy clay, work in compost or plant on a slight rise or slope.
• Sun matters, but spring sun. A bed under deciduous trees is full sun in April, before the leaves come in — it’s a great place for early bulbs.

Bulb planters and augers →

A hand-held bulb planter is fine for a couple dozen; for a hundred, a drill-driven bulb auger turns an afternoon into twenty minutes. Water the bed once after planting to settle the soil around the bulbs, then leave it alone — fall rain does the rest. Mark the spot with a label or a photo, because by the time you’re digging in that bed again in November you’ll have forgotten exactly where they are.

Skip the “bulb food” in the hole

A spring bulb already contains everything it needs to flower next year — that’s what the bulb is. Fertilizer in the planting hole doesn’t help the first bloom and can burn the new roots. And the old advice to drop bone meal in every hole has a real downside: it smells like exactly what it is to every dog, raccoon, skunk and squirrel in the neighborhood, and they will dig up your bed to find it.

If you want bulbs that repeat for years (daffodils, crocus, alliums and species tulips will; most hybrid tulips fade after two or three seasons), the feeding that matters is a light scattering of balanced, slow-release fertilizer on the surface when the shoots emerge in spring. Then let the foliage yellow and die back on its own after blooming — those six ugly weeks are the bulb recharging for next year. Cutting or braiding the leaves early is the main reason daffodils stop flowering.

A 2–3 inch layer of shredded leaves or mulch over the finished bed evens out soil temperature, hides the disturbed soil from squirrels, and is the last thing you need to do until spring.

Daffodil and allium bulbs →

Deer-proof the bed by choosing the right bulbs

This is where most bulb plans go wrong before a single bulb is in the ground. Tulips are deer candy. So are crocus (to a lesser degree) and, for squirrels and chipmunks, anything without a bad taste. A bed of 100 tulips in deer country is a spring buffet that gets eaten to the ground the week it flowers, often the night before you were going to enjoy it. Rutgers rates tulips “D — frequently severely damaged.”

• Daffodils (Narcissus) — the gold standard. Every part is toxic to deer and rodents; nothing eats them, they naturalize, and they come in dozens of forms from tiny to trumpet.
• Alliums (ornamental onions) — the onion smell keeps deer, rabbits and voles away. The big purple globes bloom in late spring when tulips would have been eaten.
• Snowdrops, winter aconite, fritillaria, grape hyacinth (Muscari), Siberian squill — all rarely browsed, and the fritillaria in particular smells strong enough to help protect neighbors.
• Hyacinths — usually left alone; the bulbs are irritating to handle, so wear gloves.

If you must have tulips, plant them deep (8 inches), interplant them with daffodils and alliums, and be ready with repellent the moment the shoots show. Against squirrels, the fix is physical: lay a piece of chicken wire or hardware cloth flat over the planted bed just under the mulch. Shoots grow through the mesh; paws don’t.

Hardware cloth and bulb cages →

The bigger picture: bulbs are the cheapest, easiest way to get color into a bed that deer have made frustrating. Choose from the resistant list, plant them deep and in drifts this fall, and you get a spring show that doesn’t depend on spraying anything.

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