Mixed bouquets in San Francisco: lilac in May, a designer's mix any month
Mixed bouquets in San Francisco set a lilac stem beside greenhouse flowers, and lilac is a May cut: the second Sunday of that month is Mother's Day in the US. The rest of a mix comes from flowers sold all year, so the real choice is which flower leads and whether a seasonal stem matters to you. San Francisco's flower calendar sets out what else moves with the seasons.
What sits beside the roses in a San Francisco mix
Several mixes pair a large flower with something lighter. One pairing puts a rose beside lisianthus, sold as Roses with Lisianthus, trading the rose's dense round head for the lisianthus's looser, ruffled one. Another puts a lily next to a gerbera, and a third tucks chamomile in beside Misty Bubbles, in the bouquet named for both.
Two more pairings work without a named rose partner. One gathers a large hydrangea head with Misty. Another builds a softer mix with lilac.
A flower's size decides its job as lead flower or filler. Roses, lilies and gerberas are the kind that fill a hand and hold the eye, so they sit at the centre and carry most of the bouquet's weight. A head as large as hydrangea's works differently: a few stems of it already read as a full bouquet on their own.
That changes what a bouquet feels like from across a room. One hydrangea head reads calm and uncomplicated; a lily paired with a gerbera reads brighter and busier. For anyone who would rather send one flower and nothing beside it, mono bouquets is the section built for that.

The months a lilac or hydrangea mix makes sense
Lilac is a May cut; hydrangea follows in summer. Both are seasonal stems, so a mix built around either one has a window rather than standing ready every month.
Lily, gerbera and lisianthus are different: all three are greenhouse-grown and in the catalogue year-round, which means a mix leaning on them does not depend on the calendar at all.
Order a lilac or hydrangea mix outside its season and the florist swaps the missing stem for one close in colour and value; the substitution shows up in the photo taken before the courier leaves, so nothing arrives as a surprise. For stems picked specifically because they are in season right now, seasonal hits is the shorter route to them.
Mixed bouquet delivery in San Francisco: a simple pair or designer work
Not every one of the mixed bouquets in San Francisco is a simple two-flower pairing. Designer Bouquet "Gentle" sits in the same section, built with a wider hand and left to the florist's judgement rather than fixed to one pair of flowers.
A bouquet can also start from a brief instead of a shelf pick: a message naming the lead flower, a rough palette and a budget brings back a few options with photos and prices, and nothing is charged before one is approved.
Flowers for an order are bought once payment clears, not kept ready on a shelf, and the finished bouquet is photographed before the courier sets out; that photo is also the point to flag anything that needs changing. Most orders go out the same day they are placed, delivery in the centre is free, and the exact timing for each bouquet is shown on its own page; delivery terms cover the rest.

Start with whichever flower should lead: roses on their own if the rose is the whole point, a pairing with lisianthus or chamomile for something softer, or lilac in May if the date allows for a seasonal stem. Where the decision is harder to pin down, designer bouquets leave the arranging to the florist.