Which flowers to plant in September for a spring garden full of blooms?

Daniel Platteau Articles Flower bulbs gardening tips

Which flowers to plant in September for a spring garden full of blooms?

In September, the garden slowly starts to change pace. Summer flowering fades, the days get shorter and the first cool nights announce autumn.

But for the gardener, this is no time to ease off.

It is in fact an excellent time to prepare spring flowering.

Many spring-flowering bulbs can be planted from autumn onwards. They will develop their roots before winter, stay dormant through the cold season, then start growing again as soon as temperatures rise.

Crocuses, daffodils, grape hyacinths, hyacinths, tulips, alliums... With a few well-chosen plantings, you can have flowers in the garden for several months, sometimes from February.

So, what should you plant in September to have flowers in spring?

Bulbs to plant in September

Bulbs are probably the easiest way to prepare a garden full of flowers for spring.

They need little work and often take up very little space at planting time. Yet a few months later, they can completely transform a bed or a lawn.

Crocuses: the first to announce spring

Spring-flowering crocuses are among the first flowers to appear after winter.

Depending on the species and the weather, some can start flowering as early as February.

They are particularly useful for:

• rock gardens;
• edges;
• naturalistic lawns;
• the foot of trees and shrubs;
• small gardens short on space.

Small species crocuses are particularly well suited to naturalising. Planted in groups, they look much more natural than a few isolated bulbs.

Spring crocuses are planted in autumn, while some autumn-flowering crocuses follow a different calendar.

Tip: rather than dotting a few crocuses here and there, plant small, irregular clumps. The effect will be much more spectacular in spring.

Daffodils: reliable and easy to naturalise

The daffodil is one of the best choices for a garden that should flower again every year with minimal maintenance.

The bulbs are ideally planted in early autumn, and September is particularly well suited.

There is a great diversity of daffodils:

• yellow;
• white;
• two-tone;
• small-flowered;
• large-flowered;
• scented;
• very early or later.

They can be planted in beds, under deciduous trees or even in a lawn.

Once established, some daffodils can stay in place for many years and gradually form fine clumps.

Note, however: the bulbs and various parts of the daffodil are poisonous if eaten. Take care not to confuse them with edible bulbs.

Grape hyacinths: small blue clusters that are very easy to live with

With their small, cluster-shaped flowers, grape hyacinths (Muscari) bring a pretty touch of blue in spring.

They are particularly effective at the front of beds or combined with tulips and daffodils.

Their small size also means they can be planted:

• in rock gardens;
• along edges;
• in window boxes;
• at the foot of shrubs;
• among perennials.

When they are happy, they gradually multiply, giving larger groups over time.

Hyacinths: for colour and above all scent

If you are looking for very fragrant flowers, hyacinths deserve a place in the garden.

Their compact spikes come in a wide range of colours: blue, pink, white, violet, yellow...

They are particularly welcome near a path, a terrace or an entrance, where their scent can be enjoyed.

They can also be grown in pots.

As with many bulbs, above all avoid spots where water lingers after rain.

Tulips: lots of colours, but a slightly different calendar

It is impossible to talk about spring without mentioning tulips.

There are thousands of varieties, with very different shapes and colours: single, double, parrot, fringed, species tulips...

Contrary to a widespread idea, you do not need to plant all your tulips in September.

Tulip bulbs can be planted from September to November. In our regions, later planting, once the soil has cooled, works very well.

This helps avoid bulbs sitting too long in soil that is still warm and damp.

For a spectacular effect, avoid planting tulips one by one.

Plant them instead in groups of at least 7 to 10 bulbs of the same variety.

And if you want tulips that flower again for several years, choose species tulips or cultivars known for their longevity. Classic garden tulips often give their best display in the first year.

Alliums: to extend the show into early summer

Alliums are not the first flowers of spring, but they are very useful for bridging the gap between spring flowering and early summer.

Their large purple, pink or white flower balls rise above the other plants and immediately add height to beds.

They can be planted in autumn and generally like sunny, well-drained spots.

A small group of alliums among lower plants easily creates a very graphic effect.

What about snowdrops?

The snowdrop is a bit of a special case.

It is one of the very first flowers of the year and can sometimes bloom while winter is not really over.

You can find dry bulbs to plant, but snowdrops generally establish better when planted "in the green", that is, after flowering, while the leaves are still present.

So it is not a plant to treat as just another bulb to buy and plant in September as a matter of course.

If you do find them as dry bulbs in autumn, plant them quickly and above all do not let them dry out.

Snowdrops particularly like partial shade and soils that stay slightly moist, for example under deciduous trees. They do not cope well with constantly waterlogged soil.

Perennials to plant in September

September is not only for planting bulbs.

It is also a good time to plant some perennials sold in pots or containers.

They then still have enough time to start rooting before winter.

Anemones

Spring anemones can bring delicate, natural-looking flowers to lightly shaded areas.

Some species do particularly well under deciduous trees and shrubs, where they make the most of the light available before the foliage fully appears.

Irises

Garden irises are also worth planting in late summer or early autumn.

But beware: a rhizomatous iris is not planted like a bulb.

The rhizome must stay partly visible, especially in heavy soils. It needs to benefit from the sun and must not be buried deep.

This small difference in planting matters: a rhizome buried too deep may flower poorly, or even rot.

Where to plant bulbs?

The choice of spot is often more important than the amount of soil or fertiliser used.

Most spring bulbs like:

• a well-drained soil;
• a sunny or lightly shaded position, depending on the species;
• a spot that does not stay waterlogged in winter.

Daffodils and some small bulbs are particularly well suited to planting under deciduous trees.

Why?

Because in early spring the trees have not yet leafed out. The bulbs therefore get the light they need to flower and rebuild their reserves.

What if your soil is heavy clay?

This is a fairly common problem in many gardens.

The classic mistake is to dig a hole, put a layer of gravel or sand at the bottom, then plant the bulb.

This is not a universal solution to poor drainage.

In very compacted soil, this thin layer at the bottom of the hole does not miraculously turn the ground into free-draining soil.

It is better to:

• gradually improve the soil structure with organic matter;
• avoid areas where water stands;
• plant slightly raised where necessary;
• create a small mound or raised bed for plants that are particularly sensitive to wet;
• choose species suited to the conditions.

Drainage is particularly important for tulips, which like fertile but well-drained soil.

How deep should bulbs be planted?

The general rule often given is to plant a bulb at a depth of about two to three times its height.

But this rule is only a guide.

Recommendations vary with the species and the soil. For daffodils, for example, a depth of about three times the height of the bulb is commonly recommended.

The best habit is therefore to check the instructions supplied with the bulbs.

And above all:

the tip of the bulb must point upwards.

After planting, firm the soil lightly without over-compacting it.

Should you water after planting?

That depends on the soil and the weather.

If the ground is already moist after several days of rain, heavy watering is generally unnecessary.

On the other hand, if the soil is very dry at planting time, watering can help bring the roots into contact with the soil.

The aim is not to soak the bed.

Moist but well-drained soil is better than constantly wet soil.

What to plant in September, October or November?

Not all species follow exactly the same calendar.

Here is a simple guide for gardeners in Belgium:

These periods are only a guide. An early or late variety, a mild winter, a cold spring or a different aspect can shift flowering by several weeks.

A tip for flowers over several months

The secret is not to plant huge numbers of flowers.

It is above all to mix plants that do not all flower at the same time.

For example:

Late winter:
snowdrops → crocuses

Early spring:
daffodils → hyacinths

Spring:
tulips → grape hyacinths

Late spring:
alliums → irises

That way, as the first flowers begin to fade, the next ones gradually take over.

Mistakes to avoid in September

1. Planting all your bulbs at exactly the same time

Each plant has its own calendar.

Daffodils can be planted relatively early, while tulips can wait until later in autumn.

2. Burying bulbs too deep

A bulb buried too deep may struggle to come up.

Follow the instructions for the species.

3. Planting in constantly waterlogged soil

This is one of the main causes of failure with bulbs that are sensitive to wet.

4. Cutting the leaves as soon as the flowers fade

This is particularly important for bulbs.

After flowering, the leaves keep working and allow the bulb to rebuild its reserves for the following year.

So remove faded flowers if necessary, but let the foliage yellow naturally.

5. Planting only flowers of the same height

A bed made up only of tall tulips can be spectacular for a few weeks, but much less interesting the rest of the time.

Combine instead:

• small crocuses;
• grape hyacinths;
• daffodils;
• tulips;
• alliums;
• perennials that will gradually take over.

One last tip: think in groups rather than individuals

A single crocus is pretty.

A dozen crocuses springing up together in the middle of a lawn can be magnificent.

The same goes for daffodils, grape hyacinths and tulips.

For a natural result, plant bulbs in small irregular groups rather than in perfectly straight lines.

You can even toss a few bulbs on the ground and plant them where they land. This technique often gives a much more natural result in a lawn or under trees.

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September is already preparing spring

The garden may seem less spectacular in September than in May or June.

Yet this is precisely when some of the most beautiful spring flowering is prepared.

A few packets of bulbs, properly prepared soil and a few hours of planting can be enough to turn an ordinary garden into a real festival of colour a few months later.

So, if you want a garden in flower as winter ends, don't only look at the flowers you have in front of you today. Look also at what you can put in the ground now.

Spring sometimes begins long before you see it.

Key points

• September is ideal for starting to plant many spring bulbs.
• Daffodils, crocuses, grape hyacinths and hyacinths can be planted from autumn.
• Tulips can be planted later, until November.
• Snowdrops are special and often establish better when planted "in the green".
• Avoid constantly waterlogged soils.
• Do not cut bulb foliage immediately after flowering.
• For a long-lasting bed, mix plants with different flowering periods.