Hey there, fellow DIYer,
Planting bulbs is the only garden job where you work for an hour in November and see the result in April without having to do anything else in between. No other job gives back so much for so little effort.
Straight to the answer: you plant spring-flowering bulbs between mid September and mid December, nose up, at a depth of roughly three times the height of the bulb. Small bulbs such as crocus and snowdrop go 5 to 8 cm deep, daffodils 12 to 15 cm, tulips 15 to 20 cm. As long as the ground is not frozen, you can plant.
And then the point that a surprising number of people miss: you do not want to plant every bulb at the same moment. Snowdrops, daffodils and crown imperials want to go in early, because they dry out fast. Tulips you want to plant as late as you can, ideally not until November, once the soil has cooled to around 10 degrees. Why? Because a tulip bulb sitting for weeks in warm, wet soil runs a much higher risk of tulip fire, a fungal disease that kills your flowers while they are still in the bud. Anyone who puts all their tulips in during September is short-changing themselves.
In this article: a full planting calendar and a depth table per type, which bulbs genuinely come back and which ones you should really treat as annuals, how to outwit mice and squirrels, the lasagne method for pots, naturalising in grass, what to do and not do after flowering, and the mistakes that cost you flowers.
Why autumn? The cold is not the problem, the cold is the requirement
A spring bulb is a complete little plant in a storage package. The leaves and the flower are already formed inside it. What still has to happen is that the bulb goes through a period of cold: only after a number of weeks at low temperature does the flower stem push up.
That is the whole reason you plant in autumn and not in spring. Without a cold period of somewhere between ten and fifteen weeks on average, you get leaves without a flower, or a flower that never makes it out.
Two practical consequences straight away:
- Being late is less serious than you think. Forgot? Plant them in January anyway, as long as the ground is not frozen. They will flower a bit later and sometimes a bit shorter, but they will flower
- Keeping bulbs until next year is pointless. A bulb that sits in the bag for a whole year dries out and is finished. Buying means planting
The planting calendar: what goes in when
The general window is September to December. But every type has its own best moment. It looks like this:
| When | What you plant then | Why exactly then |
|---|---|---|
| Mid September – early October | Snowdrop, winter aconite, snake’s head fritillary, crown imperial, Anemone blanda, autumn crocus (Colchicum, flowers straight away) | These bulbs and corms have a thin skin and dry out quickly. They want to go in as fresh as possible and still need to root before winter |
| October | Daffodil, crocus, grape hyacinth (Muscari), scilla, glory-of-the-snow (Chionodoxa), ornamental onion (Allium), camassia, bluebell | The broad middle. The soil is still workable and warm enough for rooting |
| November | Tulips (all types), hyacinth, any remaining crocus and muscari | The soil has cooled, which cuts the risk of tulip fire considerably |
| December (and January at a push) | The tulips you forgot about | Still doable, as long as the ground is not frozen. Flowering a bit later |
| March – May | Dahlia, gladiolus, lily, canna, begonia, crocosmia | These are summer flowerers and they are not hardy. They do not belong on this autumn list |
The rule of thumb behind that list: do not look at the calendar, look at the soil. The ideal planting time is when the soil temperature drops below 10 degrees and the ground is not frozen. In north-west Europe that is usually the second half of October and November.
Why tulips really do need to go in later
Tulip fire (Botrytis tulipae) is the fungus that gives you grey blotches on the leaves, deformed flowers and sometimes no flowers at all. The spores sit in the soil and thrive in warm, damp conditions.
A tulip bulb that goes in at the start of September sits for five to eight weeks in relatively warm, wet soil before the cold arrives. That is exactly the situation the fungus is waiting for. Plant in November and the soil is cold, so the bulb goes almost straight into its resting phase.
Two more tulip rules that belong here:
- Do not plant tulips in the same spot three years running. Rotate, the same way you would in a vegetable bed. Otherwise the fungal pressure in the soil builds up
- Throw away any bulb with brown, soft patches or fluffy mould. Do not plant it, because it will infect the rest
How deep? The table per type
Everyone knows the rule of thumb: three times the height of the bulb. So a tulip bulb 5 cm tall goes 15 cm deep. That is the depth to the bottom of your planting hole, with the bulb sitting on the base.
But rules of thumb are there to check against, not to guess with. Here are the actual measurements:
| Type | Planting depth | Spacing | Flowers | Comes back every year? |
|---|---|---|---|---|
| Snowdrop (Galanthus) | 5-8 cm | 5-8 cm | Feb – Mar | Yes, naturalises well |
| Winter aconite (Eranthis) | 5-8 cm | 5-8 cm | Feb – Mar | Yes, self-seeds |
| Crocus (Crocus) | 8-10 cm | 5-10 cm | Feb – Mar | Yes |
| Glory-of-the-snow (Chionodoxa) | 5-8 cm | 5-8 cm | Mar | Yes, self-seeds |
| Siberian squill (Scilla siberica) | 5-8 cm | 5-8 cm | Mar | Yes |
| Anemone blanda | 5 cm | 8-10 cm | Mar – Apr | Yes |
| Species tulip (kaufmanniana, greigii, turkestanica) | 10-12 cm | 8-10 cm | Mar – Apr | Yes |
| Daffodil, small-flowered (Tête-à-Tête, jonquilla) | 10-12 cm | 8-10 cm | Mar – Apr | Yes |
| Daffodil, large-flowered | 12-15 cm | 10-15 cm | Mar – Apr | Yes |
| Grape hyacinth (Muscari) | 8-10 cm | 5-8 cm | Apr | Yes, spreads fast |
| Snake’s head fritillary (Fritillaria meleagris) | 8-10 cm | 10 cm | Apr | Yes, in damp soil |
| Hyacinth (Hyacinthus orientalis) | 12-15 cm | 12-15 cm | Apr | Moderate, thinner flowers each year |
| Crown imperial (Fritillaria imperialis) | 20-25 cm | 25-30 cm | Apr | Moderate, unpredictable |
| Large-flowered tulip | 15-20 cm | 10-12 cm | Apr – May | Variable, see below |
| Bluebell (Hyacinthoides) | 8-10 cm | 10 cm | May | Yes, naturalises strongly |
| Camassia | 10-15 cm | 15 cm | May | Yes |
| Ornamental onion (Allium, large types) | 15-20 cm | 20-25 cm | May – Jun | Yes |
Three adjustments to that table:
- Heavy clay soil: plant slightly shallower than the table says, and put a handful of grit or sharp sand in the bottom of the hole. Bulbs rot from wet feet, not from cold
- Loose sandy soil: plant slightly deeper. In loose sand bulbs work their way upwards and end up sitting half above ground after a few years
- In pots: planting shallower is fine, because a pot cools down faster and the bulbs do not need the frost protection of deep soil. Do make sure of good drainage holes
And the most important nuance: not sure? Plant a little too deep rather than a little too shallow. Planted too deep, they usually come up anyway (sometimes a week later). Planted too shallow, they freeze, get eaten, or flop over.
The crown imperial, that eternal disappointment
The crown imperial bulb has a hole in the top where the old stem was. Rainwater runs straight into it and the bulb rots from the inside out. The fix growers have used for centuries: lay the bulb at an angle or on its side in the planting hole. Then the water runs out instead of in. Put a decent handful of grit underneath it as well.
Which bulbs genuinely come back every year?
This is the key question if you do not want to reinvest every autumn, and most articles are far too casual about it.
Naturalising bulbs are the ones that multiply and come back year after year with more flowers. You just leave them where they are. Other bulbs are bred for one perfect display and then fade away to nothing but leaves.
| Reliable returners | Variable | Often good for one year only |
|---|---|---|
| Snowdrop | Hyacinth | Large-flowered double tulips |
| Winter aconite | Crown imperial | Parrot tulips |
| Crocus | Large-flowered tulips in general | Fringed tulips |
| Daffodil (nearly all types) | Heavily bred novelties | |
| Species tulip | ||
| Grape hyacinth | ||
| Scilla and glory-of-the-snow | ||
| Ornamental onion | ||
| Camassia | ||
| Bluebell | ||
| Snake’s head fritillary (in damp soil) |
What that means in practice:
- Want to invest once and enjoy it for years? Go for daffodils, crocuses, species tulips, muscari and snowdrops. They make more bulbs every year
- Want those big, crisp blocks of tulips from the pictures? Accept that you are largely treating them as annuals and topping up every one or two years. Of the large-flowered tulips, the Darwin hybrids have the reputation for coming back the longest
- Combine. A backbone of daffodils and muscari that is always there, with a load of tulips in between every autumn for the spectacle
What the label tells you: bulb size
Professional bulb bags carry a number like 11/12 or 12+. That is the circumference of the bulb in centimetres, not the diameter. Bigger bulbs hold more food reserves and give you more and larger flowers in the first year.
- Tulips: size 11/12 is standard garden quality, 12+ gives noticeably heavier flowers
- Daffodils: a daffodil bulb with two or three noses (the bumps on top) gives you two or three flowers as well
- Cheap bags from the bargain bin are often smaller sizes. Fine for naturalising, less so for a formal flower bed
Check when buying: the bulb should feel firm, just like an onion. Soft patches, blue-green fluffy mould, or a badly dried out, papery bulb, leave those alone. A loose brown skin is not a problem.
How to plant: step by step
What you need
- A bulb planter (the tube that lifts out a plug of soil) for individual bulbs in a border, or simply a trowel for small bulbs
- A spade for larger areas, because then you would rather dig one hole than thirty
- Grit or sharp sand on heavy clay
- Gloves for hyacinths (see the warning further down)
- Chicken wire if you have mice or squirrels
Step 1: choose the spot
Most spring bulbs flower before the leaves are on the trees, so a spot under a deciduous tree is simply a sunny spot in March and April. That is why woodland plants like snowdrop and winter aconite work so well there.
Where bulbs do not do well:
- Permanently wet, heavy soil. Bulbs rot away. Fix it with grit, a raised bed, or go for snake’s head fritillary and camassia, which actually like the moisture
- Under an evergreen conifer or a yew. Too dark and bone dry
- In a lawn you keep short in April and May. See the section on naturalising
Step 2: dig and plant
For individual bulbs: lift out a plug of soil with the bulb planter, set the bulb nose up on the base of the hole, and drop the plug back on top.
For a group or a block: dig one hole at the right depth across the whole area, lay the bulbs in it, and fill it back in one go. That is much faster and the result looks more natural.
Which way is up? Nose up, flat root plate down. With round corms like Anemone blanda and winter aconite you cannot always tell. No panic: lay them on their side and they will sort it out themselves. With those two it helps to soak them in lukewarm water for a few hours or overnight first, so they get going faster.
Step 3: plant in groups, not in rows
This is the difference between “someone planted bulbs here” and “flowers grow here”.
- At least 7 to 10 bulbs per group of the same type and colour
- Odd numbers and irregular shapes. No dead straight rows and no neat circle
- Scattering really does work. Throw the bulbs across the area in an arc and plant them where they land. Only move the ones that land on top of each other
- Let groups run into each other by spacing the bulbs out a bit more at the edges
How many bulbs per square metre? For a full effect: roughly 40 to 60 large bulbs (tulip, daffodil, allium) per m², or 100 to 150 small bulbs (crocus, muscari, scilla) per m². For naturalising in grass or under trees you can space them out more generously, because they multiply on their own.
Step 4: firm down, cover over, done
Soil back, firm it down lightly, and that is it. Watering is usually unnecessary in autumn, because the soil is damp enough. Only after an exceptionally dry autumn do you give one good soaking so the bulbs can root.
Put in a marker. A cane, a stone, or note it on a little garden plan. Otherwise in February you will be digging in exactly the spot where your daffodils are. I speak from experience.
Mice, squirrels and other pests
Tulip bulbs are to mice, rats and squirrels what peanuts are to us. Daffodil bulbs, on the other hand, are barely touched: they contain lycorine, a bitter and toxic compound.
How to keep them out:
- Plant daffodils in among your tulips. The simplest trick going. The smell and taste of daffodils keep rodents at a distance
- Lay chicken wire over the planting area, just under the soil or just on top of it. In spring the bulbs come straight through it. For pots: lay a circle of wire on the compost
- Plant deep enough. A bulb at 18 cm is a lot harder to find than a bulb at 6 cm
- Clear up the bulb skins. Those loose brown flakes you leave lying around while planting are a scent trail saying exactly where the food is
- For persistent trouble: plant in bulb baskets made of plastic mesh. As a bonus, you can lift them out in one go after flowering
Bulbs in pots: the lasagne method
In a pot you can do something you cannot do in open ground: plant several layers of bulbs on top of each other, so that one pot flowers continuously from February to May. That is called a bulb lasagne.
Here is how:
- Take a pot at least 30 cm deep with drainage holes. Any shallower and you will not fit three layers in
- A layer of clay pebbles or coarse gravel 3 to 5 cm deep in the bottom for drainage
- Compost up to the depth of your first layer
- Bottom layer: the last to flower. Tulips, or large daffodils. Bulbs close together, they can almost touch but should not press against the sides
- About 3 cm of compost on top
- Middle layer: the mid-season flowerers. Small daffodils, hyacinths
- Another 3 cm or so of compost
- Top layer: the earliest flowerers. Crocus, muscari, glory-of-the-snow, species crocus. These can go really close together
- Cover with at least 5 cm of compost, roughly twice the height of the top bulb
The lower bulbs simply come up between the upper ones; they find their way past.
What you need to know about pots in winter:
- A pot freezes from every side. In a hard winter put it against the house wall, on a piece of polystyrene or a wooden board, and wrap bubble wrap around it if needed. A terracotta pot that freezes solid all the way through will crack
- Too wet is more dangerous than too cold. Stand the pot on feet or a couple of tiles so the water can get out, and keep it out of driving rain if the drainage is not good
- After flowering the compost is spent. Bulbs from a lasagne pot rarely come back well the following year. Treat the pot as an annual investment, or plant the daffodils out into the garden after they finish
Naturalising in the lawn: the mowing rule
Crocuses and daffodils in grass look wonderful. But there is one deal you have to make with yourself, and it costs you part of your spring lawn.
The rule: do not mow until the bulb foliage has completely died back and gone yellow. In practice that is six to eight weeks after flowering. That foliage is the factory the bulb uses to refill itself for next year. Mow too early and the bulb is empty next year, leaving you with nothing but floppy leaves.
In practice that means:
- Crocuses flower in February and March. You can start mowing again from around the middle of May
- Daffodils flower into April. That puts you at the end of May to the middle of June
- The smart solution: plant bulbs in a defined part of the lawn (a strip along the edge, a patch under a tree, a circle) and mow the rest as normal. That way you keep a tidy lawn and your bulbs
How to get them into grass:
- Small numbers: lift plugs with a bulb planter, bulb in, plug back
- Large numbers: use a spade to lift a square of turf 40 by 40 cm, fold it back, scatter the bulbs underneath, fold the turf over and tread it down
- Scatter the bulbs here too and plant them where they land. Regular patterns in grass always look wrong
After flowering: what to do and what not to do
This is the stage where most bulbs get ruined, and it happens out of tidiness.
| Do | Do not |
|---|---|
| Cut off the spent flower (setting seed costs the bulb energy) | Cut off the foliage while it is still green |
| Leave the foliage until it is yellow and floppy | Tie the foliage in a knot or bundle it up |
| Water once more during a dry April and May | Dig the bulbs up straight after flowering |
| Scatter a bit of compost or organic feed if you like | Tip artificial fertiliser straight onto the bulbs |
| Lift, split and replant daffodils in summer after three to five years if they start flowering less | Panic if a naturalised group has one weaker year |
For tulips you do want to keep: wait until the foliage has gone completely yellow, lift the bulbs, leave them somewhere dry and airy for a few weeks (not in plastic), remove the old root remains, and store them dark, dry and cool until November. Honestly: for most people that is more work than it is worth. Buying new bulbs takes less time and gives better flowers.
The eight mistakes that cost you flowers
- Planting tulips in September. Soil too warm, higher risk of tulip fire. Wait until November
- Planting too shallow. The classic mistake. Three times the bulb height, and deeper if in doubt
- Bulbs in wet, heavy soil without drainage. They rot away. Grit underneath or choose different types
- Cutting the foliage away after flowering. Next year you will have half as many flowers
- Too few bulbs per group. Five tulips in a square metre look pitiful. Use twenty
- Planting in neat rows. Scatter them
- Not putting in a marker. In spring you will dig up your own bulbs
- Planting summer bulbs in autumn. Dahlias, gladioli and begonias are not hardy and only go in after the last frost in spring
What does it cost?
Bulbs are one of the cheapest ways to change your garden for a whole season.
| Item | Price range |
|---|---|
| Crocus, muscari, scilla (100 bulbs) | 10 – 25 euros |
| Daffodils (50 bulbs, garden quality) | 20 – 45 euros |
| Tulips (50 bulbs, size 11/12) | 20 – 50 euros |
| Ornamental onion / large allium (10 bulbs) | 15 – 35 euros |
| Bulb planter (hand held) | 10 – 30 euros |
| Grit or sharp sand (25 kg) | 5 – 15 euros |
| Bulb baskets against mice (set) | 10 – 25 euros |
How to get more for your money:
- Buy in bulk for naturalising. Bags of 100 or 250 small bulbs cost a fraction per bulb compared with individual packets
- Choose naturalising bulbs as your base. Pay once, flower for ten years
- Order in August or early September. The choice is at its widest then, and many suppliers send the bulbs out automatically at the right planting time
- Do not buy in the January sales unless the bulbs still look firm. Half price for dried out bulbs is still too expensive
- Split and share your daffodils after a few years and swap with the neighbours
Careful: bulbs are toxic
Something that appears in almost no bulb article, and that does go wrong from time to time.
- Many flower bulbs are toxic if eaten, to people and to pets. Daffodil, hyacinth, tulip, crocus and amaryllis are all known for their toxic compounds. With daffodils, lycorine is one of them
- Dogs and cats that dig up bulbs and eat them can get seriously ill. If you have a dog that likes to dig, plant deeper, use wire, or keep the bulbs away from the spots where it digs
- Hyacinth bulbs irritate a lot of people’s skin, because of crystals in the bulb skin. Wear gloves if you are planting a large quantity
- Do not mix bulbs up with edible onions or garlic. Never store flower bulbs anywhere near your onions or shallots in the shed
Frequently asked questions
When should I plant flower bulbs?
Spring-flowering bulbs go in between mid September and December. Snowdrops, winter aconites, crown imperials and snake’s head fritillaries want planting early (September to early October) because they dry out quickly. Daffodils, crocuses and muscari can go in during October. Tulips and hyacinths are best planted in November, once the soil temperature drops below around 10 degrees. As long as the ground is not frozen, you can keep planting into January.
How deep should I plant flower bulbs?
The rule of thumb is three times the height of the bulb. In practice: small bulbs such as crocus, snowdrop and muscari 5 to 10 cm, daffodils 10 to 15 cm, tulips 15 to 20 cm, crown imperial 20 to 25 cm. On heavy clay you plant slightly shallower with a handful of grit underneath, on loose sandy soil slightly deeper. When in doubt, a little too deep beats a little too shallow.
Which flower bulbs come back every year?
Snowdrops, winter aconites, crocuses, daffodils, species tulips, grape hyacinths, scillas, glory-of-the-snow, ornamental onions, camassia and bluebell all naturalise well and come back year after year with more flowers. Large-flowered tulips (especially the double and fringed varieties) and hyacinths fall away noticeably after one or two years; in practice you treat those as temporary planting. Of the large-flowered tulips, Darwin hybrids have the reputation as the most reliable returners.
Can I cut the foliage off after flowering?
No, not while it is green. The foliage makes the food reserves the bulb uses to flower next year. Wait until the leaves are yellow and floppy, usually six to eight weeks after flowering. The spent flower you can cut off straight away, because setting seed costs the bulb energy. Do not tie the foliage up or knot it: that reduces how much light it takes in.
How do I stop mice eating my bulbs?
Plant daffodils in among your tulips (daffodils contain lycorine and are not eaten), lay chicken wire over or just under the planting area, plant deep enough, and clear up the loose bulb skins after planting. For stubborn problems you can use bulb baskets made of plastic mesh.
Can I plant flower bulbs in pots as well?
Yes, and with the lasagne method you get one pot flowering from February to May: the late flowerers at the bottom (tulips), the mid-season ones above them (daffodils, hyacinths), the early ones on top (crocus, muscari), with 3 cm of compost between each layer and 5 cm over the top. Use a pot at least 30 cm deep with drainage holes, and make sure the pot does not freeze solid all the way through in winter and does not stand in water.
I have left it too late, can I still plant in December or January?
Yes. As long as the ground is not frozen, you can plant bulbs. They usually flower a bit later and sometimes a bit shorter, but they flower. What you should not do is keep the bulbs until next autumn: they dry out and are then lost. If it really is not going to happen, plant them in pots of compost and stand those in a cold, sheltered spot outside.
To finish
Bulbs are the job with the best effort-to-result ratio there is in the garden. Two hours of work in November, and from February to June there is something to look at.
Remember three things: early types early, tulips late, three times the bulb height deep, and leave the foliage alone after flowering. The rest is a matter of buying enough bulbs, because too few bulbs is the mistake everybody makes once.
If you are out in the garden anyway, this is also the season for planters, a bulb crate on legs, a toolbox or a cold frame. For projects like that I have complete working drawings with dimensions and a materials list ready to go, so you buy the right timber in one trip. Have a look here: Fred’s DIY Plans
Cheers, Fred Schouten, handyman and DIYer through and through
PS: put a cane or a stone by every group you plant. Sounds unnecessary in November. It is not in February, when you are standing in the border with a spade.