Plant Summer Bulbs in March: Alan Titchmarsh’s Guide to Huge Blooms

While many amateur gardeners are still staring helplessly at empty beds in March, professionals such as TV gardener Alan Titchmarsh are already planning the year’s biggest colour display beneath the soil. Plant the right summer-flowering bulbs now and you could be enjoying enormous blooms from June, rather than regretting bare ground in the height of summer.

Why March is the quiet starting point for a summer of flowers

Although March can still look like late winter on the calendar, the soil is already counting down to summer. Temperatures are gradually rising, daylight hours are increasing and the ground remains moist – ideal conditions for bulbs and tubers to establish roots undisturbed.

What goes into the ground in March determines how lavishly beds, containers and window boxes burst into bloom in June.

Garden professionals regard this particular window as the key to a long flowering season from June to August. Plants have several months to develop a strong root system before dry spells and hot weather arrive. As a result, they flower more reliably, produce larger blooms and keep going for longer.

There is another benefit: summer-flowering bulbs and tubers are relatively inexpensive and easy to look after. They give less experienced gardeners quick, rewarding results. More seasoned gardeners use them to fill gaps in perennial borders or introduce carefully placed bursts of colour.

These summer bulbs should genuinely go into the ground in March

Not every bulb flowers in summer – many people know only tulips and daffodils. However, for the warmer months, it is worth considering other varieties that truly come into their own from June onwards.

For tall, dramatic borders

For flower stems that can be seen from a distance, choose these familiar favourites:

• Lilies – elegant, often fragrant, with large and refined flowers
• Gladioli – tall flower spikes, ideal for cutting and displaying in a vase
• Freesias – more delicate in appearance, but intensely scented
• Crocosmias (montbretias) – slender, arching flowers in vivid orange or red
• Ornamental alliums – spherical flower heads that bring a modern, architectural look to borders

These varieties add height and structure, especially towards the back of a border or behind lower-growing plants.

For big, show-stopping blooms

Anyone after a real “wow” factor will almost inevitably end up choosing these options:

• Dahlias – huge, frequently multicoloured flowers, from pompon forms to dinner-plate dahlias
• Begonias – abundant double blooms, also well suited to partial shade
• Bearded irises – spectacular shapes and bold, often bicoloured flowers

All three make excellent focal points in borders or can fill large containers positioned beside the patio.

For containers, balconies and small spaces

Alan Titchmarsh often uses a mix of flowering plants and companion plants in pots and small beds. The following work particularly well:

• Begonias – flower almost continuously, even in smaller containers
• Petunias – trailing varieties cascade over balcony edges like a carpet of flowers
• Verbenas – finely branched growth, masses of small flowers and exceptional staying power
• Rudbeckias – sun-like blooms that are robust and long-lasting

In window boxes and hanging baskets, these plants excel because they need little root space while delivering an enormous amount of colour.

How to plant summer bulbs properly

The basic principles are straightforward, yet they are surprisingly often overlooked. Ultimately, planting depth, position and soil determine whether the result is a success or a disappointment.

Planting depth and spacing: the rule of thumb

Most flower bulbs perform best when planted at a depth around two to three times their own height. A large dahlia tuber therefore needs to sit deeper than a delicate freesia.

Type	Recommended planting depth	Spacing
Lilies	3 x bulb height	20–30 cm
Gladioli	10–15 cm	10–15 cm
Dahlias	5–10 cm of soil above the tubers	40–60 cm
Begonias	3–5 cm	15–20 cm

Rather than scattering bulbs individually, plant them in groups of four to six of the same variety. In summer, concentrated blocks of colour make a far greater impact than a few isolated stems among perennials.

Borders or pots: what matters in each case

For borders, the essential requirement is free-draining soil. Waterlogging is the greatest enemy of almost all bulbous plants. Improve heavy clay soil by working in sand or fine grit.

For tubs and pots, use a blend of good-quality compost with a mineral component, such as clay pebbles, sand or fine gravel. Alan Titchmarsh often opts for large terracotta pots and checks the drainage holes first. He then plants the bulbs with their tips pointing upwards, fills the container with peat-free compost and leaves a watering gap of two to three centimetres below the rim.

Watering, care and securing a flood of flowers

Summer bulbs are considered undemanding, but a few essentials can make an enormous difference.

• Water thoroughly immediately after planting so that the soil and bulb settle together properly.
• Allow the soil to dry slightly afterwards and avoid waterlogging, particularly in pots.
• Keep plants evenly moist while they are growing, especially during extended dry weather.
• Remove faded flowers regularly so that plants direct their energy into fresh buds.

Those who water bulbous plants less often but more deeply give them stronger roots and a longer flowering period without breaks.

Many varieties benefit from a light liquid feed every two to three weeks during their main growing period. In good garden soil, an organic slow-release fertiliser applied at planting time is often sufficient.

Hidden pests: when inconspicuous insects ruin entire borders

One threat can be present before anything green has even appeared: tiny insects called thrips. They often hide between bulb scales, particularly on planting material that has been stored. To the naked eye, they resemble minute lines.

The insects and their larvae later feed by sucking sap from buds and leaves. Typical consequences include:

• distorted flowers that barely open
• brown marks and silvery streaks on leaves and petals
• generally weakened plants

How to prepare the bulbs

A brief additional step before planting can reduce the risk significantly:

• Use only firm, clean bulbs; discard any that are soft or mouldy.
• Carefully brush away loose soil and debris.
• Mix 1 litre of water with 1 tablespoon of gentle soft soap or mild washing-up liquid.
• Spray the bulbs, allow them to dry, then repeat the treatment after three days.

Sensitive varieties such as tulips and daffodils do not tolerate aggressive products. With gladioli, ranunculus or anemones, some gardeners also use a short soak in a mild disinfecting solution, then dry the tubers thoroughly before planting them.

What to do if damage is already visible in the border

If you noticed distorted flowers or silvery leaf markings last year, take decisive action. It is best to remove badly damaged plants so they do not remain a continuing source for future generations.

Possible measures for affected plants include:

• spraying leaves in the evening with a water and soft-soap solution of around five per cent
• placing yellow sticky traps in borders or pots
• drying lifted or harvested bulbs thoroughly and storing them in a cool place at 2–4 °C

Bulbs that have spent winter unchecked in a warm garage or boiler room should be examined critically and, if there is any doubt, discarded.

Practical March tips for lazy gardeners who want lots of flowers

If time is limited, follow a simple minimum plan: one hour of work in March in exchange for enjoyment throughout the summer.

• Plant one or two large containers densely with lilies or dahlias.
• Put groups of gladioli or begonias into gaps within perennial borders.
• Fill a sunny corner bed entirely with one variety, such as yellow rudbeckias for a “sunspot effect”.

The layering method is especially worthwhile on balconies and patios: drainage at the bottom, good compost in the middle, then a mix of bulbs and fast-growing companion plants such as verbenas or petunias on top. This means the container already looks appealing before the larger summer-flowering plants get started.

Why summer bulbs are worth considering for the long term

Many amateur gardeners buy flowering plants on impulse from the garden centre once the season is already under way – usually at a higher cost and with a shorter flowering period. Choosing bulbs and tubers deliberately in March is a much more efficient approach.

Once planted, many varieties return for years provided they have a suitable site and are not damaged by frost or excess moisture. Lilies, alliums and hardier begonias in particular can become permanent features of the garden. Over time, this creates a foundation of summer flowers that needs only a few additions each year.

Perhaps the greatest advantage is that the garden looks less accidental in summer. Instead of isolated colourful patches, it develops defined blocks of colour, graduated heights and recurring shapes. That is what separates “quite nice, somehow” from “Wow, what a garden!” – and, if you follow Alan Titchmarsh, it begins on an otherwise unremarkable day in March, with soil on your fingers.