Chrysanthemum Growing Guide: Pinch Out in June for Bushier Plants and 3x More Autumn Blooms

The Autumn Garden’s Best-Kept Secret

When most summer flowers have given up, chrysanthemums are just hitting their stride. From September through November — sometimes into December — they deliver colours that nothing else in the autumn border can match: rich bronze, burnt orange, deep crimson, pure white, and every shade of gold and pink in between.

The trouble is, most people’s experience of chrysanthemums begins and ends with a supermarket pot that collapses within a fortnight. Those plants — grown under artificial light, drenched in dwarfing hormones, and forced into flower out of season — bear little resemblance to the genuinely hardy garden chrysanthemums that can return reliably for years with almost no intervention.

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This guide covers everything you need to grow all types well: understanding the different forms, choosing hardy varieties that will actually perennialise, pinching for the bushiest plants, feeding at the right moment, and overwintering successfully whether you’re growing cottage-garden border mums or working towards your first show bench entry.

Understanding Chrysanthemum Types

Chrysanthemums divide into two broad groups that determine almost everything about how you grow them: hardy types that can stay in the ground year-round in most of the UK, and tender types that need frost-free overwintering. Within those groups, the National Chrysanthemum Society (NCS) classifies varieties across 30 numbered sections based on flower form — but for practical growing, the six main forms below cover everything most gardeners will encounter.

The RHS hardiness ratings matter here in a practical way: H4 means reliably hardy to −10°C, which covers most of England, Wales, and sheltered parts of Scotland. H3 (down to −5°C) means you’re fine in mild areas but should mulch generously or consider lifting in the north and on exposed sites. H2 means frost kills them — they must come in before October ends.

Supermarket Mums vs Garden Chrysanthemums: Know the Difference

Every autumn, supermarkets fill their displays with potted chrysanthemums at temptingly low prices. These plants have been grown in controlled glasshouses under supplemental lighting and treated with dwarfing agents (paclobutrazol and similar) to produce compact, heavily flowering plants that look spectacular in the shop. They almost never perform reliably in the garden, and they’re almost never the hardy perennial varieties that will come back the following year.

Specialist nurseries — and particularly NCS-affiliated growers — sell rooted cuttings and young plants of named, trialled varieties with known hardiness ratings. These are completely different plants from what you find on supermarket shelves. If you want chrysanthemums that will reward years of growing, buy from a specialist. The investment is modest and the difference in reliability is enormous.

The NCS website lists affiliated nurseries, and the RHS publishes a list of Award of Garden Merit (AGM) chrysanthemums — these are varieties proven in UK garden conditions through RHS trials. An AGM is the most reliable quality indicator when choosing.

How to Plant Chrysanthemums

Choosing the Right Spot

Chrysanthemums want as much sun as you can give them — a minimum of six hours of direct sun daily, in a warm and sheltered position. The RHS recommends a site that is warm, sunny and sheltered [1]. In shade they will grow leggy, produce fewer flowers, and become more susceptible to disease. South- or west-facing borders away from frost pockets are ideal.

Wind is a real enemy of taller varieties. A sheltered spot reduces the need for staking and prevents the stem damage that opens entry points for disease. I’ve found that planting against a south-facing fence not only gives extra warmth in autumn but also provides natural windbreak support.

Soil Preparation

The ideal chrysanthemum soil is fertile, moisture-retentive but free-draining, with a pH of around 6.5 [2]. Dig in a generous amount of well-rotted garden compost or manure before planting — this improves both drainage in clay and moisture retention in sandy soils.

One fact most growing guides gloss over: waterlogging in winter kills hardy chrysanthemums far more reliably than cold does. A variety rated H4 (−10°C) will often die in a mild, wet winter in heavy clay, while surviving much colder temperatures in free-draining soil. If your soil is clay, improve it with horticultural grit at planting time, or consider growing in raised beds.

For containers, use peat-free John Innes No. 2 compost in a pot with a minimum diameter of 30cm. Smaller containers restrict root development and dry out too quickly to sustain a chrysanthemum through the growing season.

When and How to Plant

Plant rooted cuttings or young plants after the last frost — mid-May to early June for most of the UK [1]. Garden-centre plants bought in late summer or autumn can go straight into the border.

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Space plants 30–45cm (12–18in) apart [1]. Good air circulation reduces the risk of grey mould and white rust, both of which thrive in dense, humid conditions. Firm the soil gently around the roots, water in well, and insert support canes immediately for taller varieties rather than waiting until they need them.

Pinching Out: How to Use the Chelsea Chop

Left to their own devices, chrysanthemums will produce a single tall stem topped with one large flower — or a small cluster of flowers at the tip. Pinching out transforms this into a shorter, bushier plant with many more flowering stems.

The technique is simple: when your plants reach about 20cm tall, remove the top 50mm (2 inches) of the main growing stem between finger and thumb, or with clean secateurs [3]. This removes the apical bud, breaking apical dominance and releasing the lateral buds below to develop into new branching stems.

The timing of pinching is what gardeners call the Chelsea Chop — named because it coincides with the RHS Chelsea Flower Show in late May. According to the RHS Chelsea Chop guide, pinching in late May or early June delays flowering by roughly four to six weeks compared to unpinched plants, and produces significantly more stems and flowers [4]. For border display, this is almost always the better approach.

A few nuances worth knowing:

• You can pinch a second time in mid-June to create an even bushier plant — but this delays flowering further, so only do this for varieties that you know will still flower before the first frosts in your location.
• For exhibition and disbud types, pinching is timed very precisely using stopping charts — the date you pinch determines the bloom date, and show growers work backwards from their target show date.
• Charm and cascade types benefit from pinching every three to four weeks throughout spring to maximise lateral branching.

How Chrysanthemums Know When to Flower

Chrysanthemums are short-day plants — but the name is slightly misleading. What actually triggers bud initiation is not the length of the day, but the length of the uninterrupted dark period at night. When nights exceed roughly 10–12 hours of continuous darkness, the plant initiates flower buds. This is why chrysanthemums flower in autumn: as nights lengthen through August and September, buds begin forming.

The practical implication: even a brief flash of light during the critical dark period — from a nearby streetlight, or a garden light left on — can delay or prevent flowering entirely. If you’re growing chrysanthemums near artificial lighting and wondering why they’re late to flower, this is often the cause.

Commercial growers exploit this mechanism in both directions: using blackout curtains to create artificially long nights and force early flowering, or supplemental lighting to interrupt nights and delay blooming — which is exactly what’s done to produce supermarket mums in full flower at any time of year. For the home gardener, the main takeaway is to position late-flowering varieties away from lights, and to know that early-flowering types (NCS Sections 22–30) will always perform better outdoors in the UK without any intervention.

Ongoing Care: Watering, Feeding, Staking and Deadheading

Watering

Water regularly throughout the growing season, keeping the soil consistently moist but never waterlogged. Container-grown plants need more frequent attention — in warm weather, daily watering may be necessary. Water at the base rather than overhead to keep foliage dry and reduce the risk of grey mould and petal blight.

Feeding

Chrysanthemums are hungry plants that respond well to a clear two-phase feeding programme:

• Vegetative phase (planting through to bud formation): Apply a balanced or high-nitrogen liquid fertiliser weekly [2]. This supports strong stem and foliage development through the growing season.
• Switch to high-potassium feed as soon as flower buds appear: Potassium supports flower development, stem strength and disease resistance. Tomato feed is ideal and widely available [2] [3].
• Stop feeding when buds show colour: Continuing to feed at this point can cause blooms to develop too soft and short-lived [2].

Staking

Insert bamboo canes at planting time for taller varieties rather than waiting until the plant leans. Tie loosely with soft twine in a figure-of-eight knot at intervals as the plant grows. For clumps of border varieties, horizontal wire or mesh stretched between stakes at 30–40cm height works well, letting stems grow through it naturally.

To manage height without pinching, you can cut taller plants back hard to 30cm in early August — this creates compact, well-branched plants but does delay flowering, so it’s mainly useful for late-season varieties in the south of England.

Deadheading

Regular removal of faded flower heads encourages the formation of new buds and significantly extends the display [1]. Cut spent heads back to the nearest healthy leaf or lateral bud. For spray types, remove individual spent blooms within the cluster as they fade rather than taking the whole stem.

Disbudding for Exhibition and Spray Types

Standard border chrysanthemums need no disbudding — they’re grown to produce the maximum number of flowers naturally. But for exhibition and cut-flower work, disbudding is central to the craft.

For disbud/exhibition types: Remove all lateral (side) buds from each stem, leaving only the terminal (top) bud. This directs all the plant’s energy into one large bloom. Begin when the laterals are small enough to remove cleanly with a thumbnail. The earlier you disbud, the larger the final bloom; leaving laterals longer before removal can result in scarring around the terminal bud.

For spray types: The opposite applies — remove the central (terminal) bud from each shoot, allowing the lateral buds to develop into a uniform spray of equally-sized flowers. This prevents the central bud from developing faster than the rest and throwing off the symmetry of the spray.

Exhibition growers also manage bloom date precisely by controlling the stopping date (the date of the final pinch). Using published stopping charts — available from the NCS and specialist suppliers — growers work backwards from their target show date to calculate when to stop, which varies by variety from 8 to 14 weeks before bloom.

How to Overwinter Chrysanthemums

Hardy Border Types (H3–H4)

After flowering, once the first hard frost has blackened the foliage, cut plants back to 15–20cm above ground level [1]. Remove the cut stems from the garden to reduce overwintering sites for pests and fungal spores.

Apply a thick layer (at least 7–8cm) of organic mulch over the crown — straw, bark chips, or well-rotted garden compost all work [1]. The mulch does not significantly insulate against cold; its job is to keep the crown slightly dry and buffer against rapid freeze-thaw cycles that can heave plants out of the ground.

In exposed, frost-prone sites or on heavy clay, even H4 varieties are safer lifted. In mild parts of southern England with free-draining soil, most H4 varieties will overwinter reliably in the ground with just the mulch treatment.

Lifting and Storing as Stools (All Types, Exposed Sites, and Tender Varieties)

Lifting chrysanthemums produces what growers call stools — the old root system that will produce new basal shoots the following spring.

1. After flowering, cut top growth back to 15cm.
2. Lift the plant carefully, shaking off excess soil from the roots.
3. Trim roots to about 15cm length and remove any dead or diseased material.
4. Place the stools into shallow trays or boxes with barely moist, open compost — a 50:50 mix of multi-purpose and perlite works well. Do not bury the crown deeply.
5. Label clearly — stools look identical over winter and you will regret not labelling them.
6. Store in a frost-free space: an unheated greenhouse, cold frame, or cool garage at around 5°C (40°F) [3]. Avoid anything warmer than 10°C or the stools may start shooting too early.
7. Keep compost barely moist throughout winter — stool rot is caused by overwatering in storage, not underwatering.

For tender florist and exhibition types grown in pots, move plants to a frost-free greenhouse (minimum 5°C) by the end of October, before the first hard frosts arrive.

Post-Winter Stool Care

In late January or February, move stored stools into a slightly warmer position (10–12°C) with good light to stimulate new basal growth. New shoots — short, fresh green growth emerging from the base of the old stems — are what you’re waiting for. These become your propagation material: basal cuttings taken at 5–8cm length, with a clean cut just below a node, root readily in spring. For full instructions on all three propagation methods, see our chrysanthemum propagation guide.

Divide stools every two to three years in spring to maintain vigour [3]. Each division should have healthy roots and at least two or three new basal shoots attached.

Pests and Diseases

Aphids

The chrysanthemum aphid (Macrosiphoniella sanborni) and various other aphid species colonise shoot tips and leaf undersides, causing distorted growth and producing honeydew that encourages sooty mould [5]. Check new growth regularly from May onwards. Knock colonies off with a forceful jet of water, encourage ladybirds and lacewings, or use an insecticidal soap spray for heavier infestations.

Capsid Bugs

Common green capsid (Lygocoris pabulinus) and tarnished plant bug cause distinctive damage: many small, irregular holes with brown edges appear in the leaves, and buds may fail to open properly or develop unevenly [6]. The frustrating thing about capsid bugs is that by the time you see the damage, the insects have usually moved on. The RHS recommends tolerating the damage where possible — plants rarely suffer lasting harm. Removing dead vegetation in late winter destroys overwintering sites for the tarnished plant bug [6].

Chrysanthemum Leaf Miner

The chrysanthemum leaf miner (Chromatomyia syngenesiae) is a small fly whose larvae tunnel through leaves, leaving pale sinuous tracks on the upper surface [7]. Two generations occur outdoors — early summer and late summer/autumn. For light infestations, remove affected leaves and crush visible larvae at the ends of tunnels. Biological control using parasitic wasps (Dacnusa sibirica or Diglyphus isaea) is effective in greenhouses. The RHS notes that plants typically survive and still produce flowers even with significant leaf mining [7].

White Rust (Puccinia horiana)

White rust is the most serious disease of chrysanthemums in the UK. Pale yellow spots appear on the upper leaf surface; on the underside, buff-coloured pustules develop that turn white or cream in humid conditions. Affected leaves eventually shrivel and brown, and heavily infected plants become stunted [8].

The fungus spreads via airborne spores and infected cuttings, thriving in cool, wet conditions from late summer into autumn. Cultural controls are the main line of defence — the RHS advises against fungicides due to environmental concerns [8]. Remove and destroy affected leaves promptly, avoid overhead watering, and never take cuttings from infected plants. Dormant stools can be treated with hot water at 46°C for five minutes, which kills the pathogen in rootstocks without damaging the plant [3] [8].

Petal Blight and Grey Mould (Botrytis cinerea)

Petal blight causes light brown spots on the lower petals that spread rapidly in humid conditions to cover whole blooms in dusty grey-brown mould [9]. Cool, overcrowded growing conditions are the trigger. No fungicides are approved for home gardeners in the UK; cultural management is the only tool: remove and destroy infected flowers and leaves immediately, improve air circulation by spacing plants adequately, and avoid watering from above [9].

Recommended Chrysanthemum Varieties

For wildlife value, choose single-flowered forms — they provide accessible late nectar for bumblebees and butterflies at a time when most other flowers have finished. ‘Clara Curtis’, ‘Emperor of China’, and ‘Perry’s Peach’ are the strongest performers for pollinators.

Companion Plants for the Autumn Border

Chrysanthemums pair beautifully with other late-season plants that share the same growing conditions. The best companions are those that bloom at the same time or slightly before, extending the overall display [1]:

• Asters / Symphyotrichum — the natural partner; same conditions, similar daisy form, complementary colours. ‘Monch’ (lavender-blue) is a classic alongside orange and bronze mums.
• Sedum / Hylotelephium (‘Herbstfreude’ / Autumn Joy) — flat plateaux of russet-pink flowers attract the same late pollinators; shared drought tolerance once established.
• Ornamental grasses — Miscanthus, Pennisetum, and Calamagrostis provide movement, texture and warm feathery tones that complement bronze and orange chrysanthemum cultivars perfectly. Taller grasses also provide physical shelter for neighbouring plants.
• Rudbeckia — yellow and gold daisy flowers; blooms slightly earlier to bridge summer and autumn, then chrysanthemums carry the baton.
• Helenium — bronze, russet and gold tones from August into September; creates a seamless transition to chrysanthemum season.
• Dahlia vs Chrysanthemum: Fall Flower Face-Off

For more ideas on building an autumn border, see our Autumn Garden Colour guide. For comprehensive winter preparation of the whole garden — including mulching and lifting tender plants — see How to Winterise Your Garden.

Chrysanthemum Care Calendar

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Frequently Asked Questions

Will chrysanthemums come back every year?

Hardy garden chrysanthemums (H3–H4 varieties, including Korean and Rubellum types) will return each year in most of the UK if grown in free-draining soil with a mulch over the crown in winter. Florist and exhibition types are tender and must be lifted and stored annually. The key point is getting the right variety — see the Varieties section above.

Why did my chrysanthemum die over winter?

In most cases, winter death is caused by waterlogging rather than cold — I lost several ‘Ruby Mound’ plants one mild winter in a low-lying bed that sat wet from November to February, while identical plants in a raised, gravelled bed came through without any protection. Even H4-rated varieties will die in sodden clay soil in a mild, wet winter. Improve drainage at planting time or grow in raised beds. Always apply a mulch to the crown after cutting back in autumn.

When should I pinch out chrysanthemums?

Pinch when plants reach 20cm tall, from late May (the Chelsea Chop timing). Remove the top 5cm of the main stem. This produces more stems and more flowers, and delays flowering by four to six weeks. For exhibition types, the stopping date is calculated from your target show date using NCS stopping charts.

Can I grow chrysanthemums from a supermarket pot?

It’s possible but unreliable. Supermarket chrysanthemums are typically florist varieties treated with dwarfing agents and grown under artificial light. They’re not the hardy garden varieties that will perennialise reliably. Once flowering finishes, they can be cut back and kept frost-free over winter, but long-term results are inconsistent. For reliable performance, buy from a specialist chrysanthemum nursery.

What’s the difference between spray and disbud chrysanthemums?

Spray types produce a cluster of flowers per stem by removing the central bud — the result is a balanced spray of smaller, similar-sized blooms, ideal for cutting or border display. Disbud types have all lateral buds removed, directing all energy into one large terminal flower — the classic exhibition or florist chrysanthemum. Both techniques are described in the Disbudding section above.

Even healthy chrysanthemums can develop yellow leaves, aphid infestations, or fungal diseases. Our chrysanthemum problems guide covers every common issue with a diagnostic table to help you identify symptoms and act quickly.

Sources

1. RHS — How to Grow Chrysanthemums (rhs.org.uk/plants/chrysanthemum/growing-guide)
2. Chrysanthemums Direct — Fertiliser Guide
3. Chrysanthemums Direct — Overwintering Treatment
4. RHS — The Chelsea Chop (rhs.org.uk/pruning/chelsea-chop)
5. Clemson University HGIC — Chrysanthemum Diseases and Insect Pests
6. RHS — Capsid Bugs
7. RHS — Chrysanthemum Leaf Miner
8. RHS — Chrysanthemum White Rust (rhs.org.uk/disease/chrysanthemum-white-rust)
9. Penn State Extension — Chrysanthemum Diseases