Philodendron 'Birkin'

• Moderate care
• Needs bright indirect
• Let it dry back partway
• Grows upright
• Toxic to pets

The Birkin is a philodendron that happened by accident. The usual account is that it turned up as a mutation on 'Rojo Congo', a dark, red-flushed hybrid, and the cream pinstripes that make it worth buying came with it. They're also the part of the plant that isn't settled. Each new leaf is drawn a little differently, and the pattern can drift: lighter in one leaf, darker in the next, now and then almost white.

That changes what looking after it means. Keeping a Birkin alive is easy. It's compact and slow, and asks for little beyond good light and a pot that dries back. Keeping it looking like a Birkin comes down to light, and to knowing the difference between two kinds of fading. Stripes can fade because the plant is short of light, or because it's turning back into the plant it came from. The first is a light problem. The second isn't, and moving the plant won't touch it. So work out which one you're looking at first.

Before you buy

Variegation costs a plant something. The cream stripes carry little or no chlorophyll, so every striped leaf does its work with less green surface than a plain one. Give a Birkin bright, indirect light and it keeps producing the pattern you bought it for. That means right beside a bright window that doesn't take hard afternoon sun, or a metre or two back from a sunnier one. An east- or north-facing room is the usual starting point, and the Shadow Test decides.

In lower light the plant does what any plant short of light does. It puts out leaves with more green in them, smaller, on longer stems, often leaning toward the window. It isn't dying. It's choosing chlorophyll over stripes. Move it into better light and the next leaves come in brighter. The leaves it has already made stay as they are.

The other end of the range matters too. The white sections have nothing to protect them, so direct sun through glass scorches them first: dry brown patches that start in the cream and spread. Soft morning sun is fine. Hot afternoon sun isn't.

The Shadow Test: hold your hand about 10cm above a leaf during the brightest part of the day for that spot — not midday, since an east-facing room peaks in the morning and a west-facing one in the afternoon — and look at the shadow. A distinct shadow means light the plant can use. A faint one means you're in the lower part of its range. Barely any shadow at all means the spot is too dim to keep a Birkin striped. You're not looking for direct sun, and the edges of the shadow don't matter. You're checking whether enough light reaches the leaf to cast a visible shadow at all.

A Birkin wants to dry back partway between waterings. It shouldn't stay damp, and it shouldn't go bone dry. The wet end is the one that gets it into trouble. It's a self-heading philodendron, so everything grows from a single crown sitting right at the mix line. A pot that never gets the chance to dry back leads to soft roots and, eventually, a soft crown. Going too far the other way is less dangerous but shows up faster, because the white sections crisp before the green ones do.

The Pot Weight Test: water thoroughly, let it drain, then lift the pot. That's your full weight, and it's the reference point for everything after — commit it to your hands rather than your head. Lift it again every so often until you learn how quickly that particular pot loses weight.

Weight is the test because the surface misleads. The top of the mix dries first and fastest, so it can feel dry to the touch while there's still plenty of water sitting further down — which is how people overwater while believing they've checked.

Water the mix, not the centre of the plant. Water left sitting where the new leaf unfurls, especially in a cool, still room, is the one place you don't want it. Water until it runs from the drainage holes, let it drain, then empty the saucer or cachepot. A Birkin sitting in a puddle at the bottom of a decorative pot is the most common way this plant is lost. There's more on how to water houseplants if you want the full picture.

Like most philodendrons, a Birkin's roots want air as much as water. In a dense mix they sit in a wet, airless mass and start to fail. In a chunky mix there's room between the pieces for both. Because a Birkin grows slowly and stays compact, it can sit in the same pot for a long time, so the mix has to hold its structure for that long too.

The Finger Probe Test: this one reads the mix, not the watering decision — weight tells you when to water, the finger tells you whether the mix can still do its job. Push your index finger in as far as it'll go. If it moves through and you can feel distinct pieces — bark, grit, fibre — with some give between them, the structure is still working. If it meets a dense mass that smears like paste and holds the shape of your finger, the mix has broken down and lost its air. Water running around it rather than soaking in means it's gone hydrophobic. A wall of roots with barely any mix left means it's outgrown the pot. A sour or swampy smell suggests the root zone is staying too wet and poorly aerated — investigate now, not later.

A Birkin doesn't need a big pot and doesn't want one. Pot up one size when the Finger Probe Test finds a wall of roots, and set the plant at the same depth it was growing, with the crown at the mix line, not below it. Spring is the easiest window, but the signals decide when, not the calendar.

A Birkin is a slow grower, and the variegation makes it slower still. Feed when it's actively putting out leaves and back off when it stops. Food won't push it along faster than its light allows, and it won't bring the stripes back. If the plant has stalled, look at light first.

Stripes fading: light or reversion?

Two different things make a Birkin's stripes fade, and on any single leaf they can look alike. Read the trend across the last few leaves, not one leaf.

Low light gives you new leaves with more green and less cream, but they're still recognisably Birkin leaves, with the same shape and the same stem colour and just a quieter pattern. The leaves often get smaller and the stems longer. Fix the light and the next leaves improve.

Reversion is the plant losing the mutation, and it shows up two ways. Either new leaves come through coppery-red and mature to dark green on burgundy stems, which is the look of its 'Rojo Congo' parent, or they come in plain green, often larger than a Birkin leaf. A half-striped leaf is usually where it starts. One plain leaf proves nothing, because variegated plants throw the odd one. A run of them, each carrying less pattern than the last, is reversion. Better light won't change it, because the change is in the growing tip, not the room.

If you're not sure which you've got, give the plant a few leaves in good light. Stripes lost to low light come back. Stripes lost to reversion don't. A fully reverted Birkin is a healthy, good-looking philodendron. It just isn't the one on the label.

Light won't bring a reverted Birkin back, but a cut sometimes can. On an established plant that has grown a short stem, take the reverted top off above a node with clean scissors. The stump often reshoots from the buds below, and if the tissue there still carries the pattern, the new growth comes back striped. It isn't guaranteed, and it costs you the top of the plant, so wait until the trend is clear. The other way back is a basal shoot with better striping than the main crown: separate it and grow it on (see Propagation).

Propagation

A Birkin isn't a plant you take a quick cutting from. It's self-heading, so there are no long vines with nodes to snip, and most commercial plants come from tissue culture. At home there are two realistic routes.

The easier one is division. Older plants sometimes push a second shoot from the base. Once it has a few leaves and roots of its own, ease the plant out of the pot, separate the offset with clean pruning scissors, and pot it up on its own.

The harder one is a top cutting. You take the crown off an older plant that has grown a short stem with a few aerial roots, and root it. The remaining stump will often reshoot. It works, but it's a commitment, and the cutting's stripes will be whatever that growing tip was producing.

Cleaning the leaves

Broad, glossy leaves collect dust, and on a variegated plant that's light it can't spare. Wipe them every few weeks with a soft, damp cloth. Neem Oil Leaf Shine helps lift dust and grime and leaves the foliage clean without a heavy residue. Spray the cloth, not the leaves, and support each leaf from underneath as you wipe.

Common problems

Stripes fading, new leaves greener: Light first, so run the Shadow Test. If the new leaves are also darker, redder and larger, see reversion above.

Lower leaves yellowing: One at a time, oldest first, as new ones open, is normal. A self-header sheds its oldest leaves as it grows. Several at once, or yellowing with soft stems, means it's time to lift the pot. If it's still heavy, the mix has been staying too wet. Check the roots, and check the mix with the Finger Probe Test.

Brown, crispy patches in the cream sections: Sun first: scorch shows on the leaves facing the window, as dry patches in the cream. If the spot is right and the browning starts at the tips and edges, the plant is drying back too far between waterings.

Small leaves, long stems, plant leaning: Light. The plant is stretching toward the window. Move it closer and turn the pot now and then.

An all-white leaf: Nothing to fix. It's the variegation landing all in one leaf. With almost no chlorophyll it tends not to last as long as the others and may brown off early. Leave it until it does, then remove it at the base.

Common pests

Whenever you find one of these, check the plants around it too. All three move between plants.

Thrips: Silvery, scratched-looking patches and tiny black specks, usually on the undersides and on new leaves as they unfurl. Isolate the plant and check new growth closely before it opens.

Mealybugs: White, cottony tufts tucked where the leaf stems meet the crown and along the undersides of the veins. Isolate the plant and dab them off with a cotton bud.

Spider mites: Fine webbing and pale stippling on the leaves, more common in warm, dry rooms. Isolate the plant and rinse the undersides of the leaves.

Why does every leaf look different?

Because the Birkin's pattern isn't written evenly into the plant. The likeliest explanation is that it's a chimera: a growing tip built from layers of cells, some that make chlorophyll and some that don't, and every new leaf draws on those layers in slightly different proportions. A leaf that draws more from the pale cells comes out lighter, and one that draws more from the green comes out darker. That's also why the pattern can drift, and why, given time, the green can take over and the plant reverts.

That's well established for variegated plants in general. Nobody has mapped the layers in a Birkin specifically. The stripes also tend to grow bolder as the plant matures, which is one more reason not to judge a young plant on its first few leaves. What's safe to say is this: genetics decides whether the pattern is there, and light decides how much of it the plant can afford to show.

Good to know