Planting bulbs too deep? The 3‑finger rule old gardeners use for perfect spring blooms every time

Cold soil, low sun, a bag of bulbs that looked far fewer once you tipped them out on the path. You knelt, guessed a bit, pushed them into the earth and forgot about them. Months later, spring arrived with fanfare in next door’s garden - and a rather awkward silence in yours. A few leaves, the odd bloom, lots of bare patches. The bulbs were in there somewhere. They just were not playing along.

Most of the time, the problem is not the bulb, the compost or the weather. It is the depth. Too deep and they struggle up, if they make it at all. Too shallow and frost, drought or a hungry squirrel finds them first. Seasoned gardeners rarely reach for a ruler in the drizzle. They reach for something they always have with them: their fingers.

There is a quiet little trick many older gardeners use: the 3‑finger rule. Once you know it, you stop guessing - and your spring beds stop sulking.

Why planting depth matters more than you think

A bulb is a battery. All the energy for that first spring show is already packed inside. Depth decides how much of that energy goes into flowering, and how much is wasted just reaching daylight.

Plant too deep and the shoots climb for longer through cold, heavy soil. By the time they reach the surface, they are thinner, later and often weaker. In bad cases, they never make it at all, especially in compacted clay or waterlogged beds.

Plant too shallow and you get a different set of troubles. Frost can nip the growing tip. Sudden dry spells hit harder. Large bulbs can work themselves to the surface over a couple of seasons, leaving them wobbling in gaps and more likely to flop or topple. Animals also find them more easily when they sit just under the surface.

Depth is not about precision to the millimetre. It is about landing in the “just right” band for each bulb. That is where the 3‑finger rule quietly earns its keep.

The 3‑finger rule, explained

The classic advice is to plant most bulbs at a depth of roughly two to three times their own height. Helpful on paper, awkward in the mud. The 3‑finger rule turns that into something you can measure in the dark.

Put simply:

• Lay three fingers flat on the soil - usually your index, middle and ring fingers side by side.
• The height of those three fingers is roughly how much soil should sit above the top of a medium‑sized bulb.
• For very small bulbs, you may only need one or two fingers of soil; for very big ones, you aim for three fingers (sometimes a touch more) of cover.

On most adult hands, three fingers together measure around 4–6 cm. That lines up remarkably well with the “two to three times the bulb’s height” rule for the common spring stars: daffodils, tulips, hyacinths, alliums.

It is not geometry. It is a quick field measure you carry everywhere.

How old gardeners actually use it

Out in the garden, it looks like this:

1. Make the hole
   Use a hand trowel, bulb planter or even the corner of a hoe to open a planting hole or slit.

2. Drop in the bulb the right way up
   Flat side or roots down, pointed or shoot end up. If in doubt, lay it on its side - the bulb will sort itself.

3. Check the depth with your fingers

   • Place your fingertips gently on the top of the bulb.
     
   • Stack or “walk” your fingers up the side of the hole until they are level with the soil surface.
     
   • Adjust the depth so you will end up with around three finger‑widths of soil over the bulb for medium to large bulbs.

4. Backfill and firm
   Replace the soil, crumble any big clods and press lightly with your palm to remove air pockets.

After you have done this a couple of times, you stop counting consciously. Your hand remembers how “deep enough” feels.

The 3‑finger rule is less about accuracy and more about consistency. Consistent depth means even flowering and a border that looks planned, not patchy.

Adapting the rule for different bulbs

Not every bulb wants the same blanket. Think in bands rather than exact numbers, and use your fingers as a guide you adjust.

Small bulbs (crocus, snowdrops, grape hyacinths)

These have tiny reserves and slender shoots. Bury them too deep and they lose the race with late frosts and spring weeds.

• Aim for 1–2 fingers of soil above the bulb.
• In numbers, that is usually 5–7 cm deep in light soil, slightly less in heavy clay.
• In lawns, keep to the shallower end so the grass can recover after you cut.

Medium bulbs (most narcissi, standard tulips)

This is where the full 3‑finger cover comes into its own.

• Aim for 3 fingers of soil above the bulb.
• That usually means your planting hole is 10–15 cm deep in lighter soil, a little shallower in heavy clay.
• Deeper planting steadies tall daffodils and tulips against wind and gives them cooler soil for summer rest.

Big bulbs (large alliums, crown imperial, big hyacinths in beds)

These need an anchor. Their flower stems are tall and can act like sails in March winds.

• Aim for 3–4 fingers of soil above the bulb.
• In practice, that is 15–20 cm deep in many gardens, adjusted for soil type.
• In wet, sticky soil, do not chase the full 20 cm. Go slightly shallower and improve drainage instead.

A quick cheat sheet:

Bulb type	Typical depth in open ground	3‑finger shorthand
Crocus, snowdrops	5–7 cm	1–2 fingers of cover
Daffodils, small tulips	10–15 cm	~3 fingers of cover
Large tulips, alliums	15–20 cm	3–4 fingers of cover

Use this as a starting point, then let your soil and your fingers fine‑tune it.

Soil, pots and slopes: tweaking the depth

Depth on a label assumes average, well‑drained soil. Real gardens are rarely that tidy. A few small adjustments keep the 3‑finger rule working.

• Heavy clay
  Clay holds water and can sit cold and sour in winter. Planting too deep here is a common way to rot bulbs. Stay at the shallower end of each range and, if you can, stir in grit or compost in the planting zone.

• Very light or sandy soil
  Sand drains fast and warms quickly. Bulbs can safely go a touch deeper to help them stay cool and moist. Add a finger’s worth of depth rather than a spade’s.

• Raised beds and slopes
  Because water runs off, you can stick to standard depths. On very steep banks, plant a little deeper to help bulbs hold on.

• Containers
  Pots heat up faster and dry out more. Still use the finger guide, but remember the whole pot is shallower than the open ground. Ensure there is at least one full finger of compost under the base of each bulb as well as your cover on top.

Think of the 3‑finger rule as the middle lane. Your soil tells you whether to nudge slightly left or right.

Common depth mistakes (and how to rescue them)

Even careful gardeners misjudge it now and then. The good news: bulbs are tougher than they look, and you often get a second chance.

• Planted far too deep
  Symptoms: nothing appears, or shoots emerge very late and weak.
  Fix: in late spring or summer, once the foliage has died down, lift a few bulbs and check. If they are sitting very deep, replant them at the right depth immediately or in early autumn.

• Barely covered bulbs
  Symptoms: bulbs showing at the surface, flowers that flop or snap, damage after hard frost.
  Fix: top up with compost or soil to give them at least their finger’s worth of cover. For pots, you can underplant with a shallow‑rooted annual to help shade and hold the soil.

• Uneven depth in the same patch
  Symptoms: flowers at random heights, an untidy “staggered” effect.
  Fix: when re‑doing a bed, dig a single, broader planting trench rather than lots of individual holes. Set the base of the trench level, then use your fingers to check cover as you go.

• Waterlogged pockets
  Symptoms: bulbs disappear entirely; when dug up, they are mushy or smell sour.
  Fix: depth was probably fine, drainage was not. Next time, add a little grit under the bulbs or pick a drier spot rather than planting shallower alone.

A simple planting routine for reliable spring colour

Once you know the 3‑finger rule, you can turn bulb planting into a quick autumn ritual rather than a guessing game.

1. Lay out the bulbs on the soil
   Space them where you want the flowers to appear, before you dig. This avoids packed clumps and awkward gaps.

2. Dig a shared trench for each group
   It is faster and helps you keep depth consistent. Aim for a flat bottom, not a cone.

3. Place bulbs on the base, points up
   For mixed displays, taller bulbs like tulips go slightly deeper at the back, smaller bulbs a little shallower at the front.

4. Use your fingers to check cover
   Rest your fingertips on the bulb, then measure to the soil line. Adjust until you have the right number of fingers’ cover for that bulb type.

5. Backfill, firm and label
   Replace soil, press gently, then add a label before your memory fades and the weather closes in.

6. Water once if the soil is dry
   This settles soil around the bulbs and starts root growth, especially important for pots and raised beds.

Do this once each autumn and, by spring, that quiet little 3‑finger trick will be written all over your borders - in straight stems, full flowers and beds that burst into life together.

FAQ:

• Can bulbs really “pull themselves” to the right depth if I plant them wrong? Some bulbs can adjust slightly over several seasons by making contractile roots, but they will not fix extreme mistakes. It is better to get close to the right depth from the start using the 3‑finger guide.
  
• Does the 3‑finger rule change for very large hands or children? Not dramatically. The rule is a guide, not a prescription. If your fingers are wider, your bulbs will be a touch deeper, which is usually fine. With children, use 3 fingers for small bulbs and 4 for big ones to compensate a little.
  
• What about planting bulbs in grass for naturalising? Use the same finger depths, but err slightly shallower so the grass can recover and you can still mow once the foliage has died back. A bulb planter or long narrow trowel works well here.
  
• Do I need to change depth in very cold parts of the UK? Where winters are harsher, depth helps insulation. You can go half a finger to a finger deeper in free‑draining soils, but still avoid burying bulbs too far in heavy clay. Mulch on top is often safer than chasing extra depth.
  
• If bulbs have already sprouted in the bag, should I still follow the rule? Yes, but handle them gently. Plant so the sprout just sits at or just below soil level, then make sure the bulb itself still has its proper finger’s worth of cover beneath.