Jamaica Plain's Halloween Saturday Has One Hard Choice, and It Comes at 1 P.M.

Halloween falls on a Saturday this year. In Jamaica Plain, that turns four separately run events into one schedule that goes from noon to 10:30 p.m. The Arnold Arboretum, JP Centre/South Main Streets, Hyde Square Task Force and Franklin Park Zoo each planned on their own. On paper, their times mostly line up end to end.

The two exceptions are worth planning around. At 1 p.m. the Arboretum's storytime and the start of the Canine Costume Parade happen at the same moment. If the weather turns, each organizer has a different backup plan, so the Saturday schedule breaks into separate Sunday pieces.

Here's the order of the day, starting with the two events that open at noon.

Two Starts at Noon

The Arboretum's Wicked Plants: A Botanical Halloween runs on the Hunnewell Lawn from noon to 3 p.m. It's free, there's no registration, and the Arboretum calls it appropriate for all ages. The topic is the collection's most sinister plants: species that defend themselves with spiky thorns, sticky latex and chemical warfare, plants that poison their neighbors, plants with explosive seed dispersal, and some that glow under black light. The lawn is flat and right off the paved road, which helps if you're bringing a stroller or a wagon. The Arboretum gives the address as 125 Arborway, the Hunnewell Building.

Also at noon, registration opens on the lawn of First Baptist Church at 633 Centre St. for the 22nd JP Canine Costume Parade. Registration is in person only and costs $10. You have to pay it for your dog to be eligible for the costume contest, which awards first, second and third place. All of the money goes to Shultz's Guest House Dog Rescue in Dedham.

The organizers point out that this year the parade falls on Halloween itself. On a regular weekend, the parade and the botanical event might never compete. This year they share the same three-hour window.

The 1 P.M. Collision

The parade leaves First Baptist at 1 p.m. and goes down Centre Street to the Loring Greenough House at 12 South St. At that same hour, back on the Hunnewell Lawn, the Arboretum's page says:

No need to register, just stop by the Hunnewell Lawn between 12:00 and 3:00pm. Kids storytime at 1:00pm!

A household with both a costumed dog and a young child has to pick one. The rest of the timing gives you some room, though. Wicked Plants runs until 3, so a family can watch the parade, see the red carpet and still get to the Arboretum before the lawn closes. You can also do it the other way: go to storytime, then skip the parade and catch the dogs at the finish. The red carpet starts at 1:30 p.m. at the Loring Greenough House, and the dogs walk it once they've all arrived. The organizers welcome spectators.

The red carpet is a very local production. Brad Brown of Blue Frog Bakery emcees. The judges include City Councilor Ben Weber and Dr. Jonathan Levine of JP Animal Clinic, with more to be announced. The sponsors are mostly neighborhood names too: TCB The Cooperative Bank, The Mindful Mutt Doggy Day Care and Boarding, First Church in Jamaica Plain Unitarian Universalist, and Happy Tails Market.

The parade's start also sits near one of Centre Street's newer storefronts. Jamaica Plain News reported in September that Edwin Barber Studio had opened at 636 Centre St., one of two new ground-floor tenants in a building that had been vacant for a long time. If you're waiting at 633 Centre St. for the parade to step off, you're looking at that block's newest storefronts.

From the Red Carpet to Mozart Park

Once the dogs have walked the carpet, the next event starts at 3 p.m. Hyde Square Task Force's Annual Halloween Fiesta runs from 3 to 4:30 p.m. at Mozart Park, 10 Mozart St. It's free, and you don't need to RSVP. Meet Boston's listing describes an afternoon of games, music, crafts and treats for the whole family in Boston's Latin Quarter.

That makes 3 p.m. the day's handoff point. Wicked Plants ends just as the Fiesta begins, so the Arboretum crowd and the parade crowd both have somewhere to go next. Here's the full afternoon:

1. Noon to 3 p.m. Wicked Plants on the Hunnewell Lawn, with kids' storytime at 1.
2. Noon. Parade registration on the First Baptist Church lawn, 633 Centre St.
3. 1 p.m. The Canine Costume Parade steps off down Centre Street.
4. 1:30 p.m. Red carpet at the Loring Greenough House, 12 South St.
5. 3 to 4:30 p.m. Halloween Fiesta at Mozart Park, 10 Mozart St.
6. 5 to 10:30 p.m. Boston Lights at Franklin Park Zoo, with last entry at 9:30.

Spectators can watch everything from noon to 4:30 p.m. for free. The only charge before dark is the $10 to enter a dog in the costume contest. After that, Boston Lights needs a ticket.

There's also a chance for an early dinner near Green Street. In September, Jamaica Plain News reported that the Tacoswey and Suya Joint food trucks had been assigned a spot outside Green Street station through the city's food-truck program. The trucks were expected to stay through October, and Tacoswey planned to serve Tuesday through Saturday, 3 to 10 p.m. If that schedule held, Halloween would be the program's last Saturday of the month there. Suya Joint was only there on some days.

After Dark, at the Zoo

Boston Lights: A Lantern Experience opens at Franklin Park Zoo at 5 p.m. and runs through Nov. 8, from 5 to 10:30 p.m. Zoo New England's page says the Halloween additions this season are talking pumpkins and skeletons. The main lanterns cover coastal South Africa, big cats, the Grand Canyon and the ocean, plus lantern tunnels close to 100 feet long inspired by bamboo and peacock feathers.

The details here matter more than at the free events earlier in the day:

• Every guest needs a ticket, but children under two get in free.
• A Boston Lights ticket doesn't include daytime zoo admission.
• The gate sells tickets if any are left, but at higher prices, and the zoo warns that some evenings sell out.
• All sales are final and can't be moved to another date. The VIP ticket, the only one good any night, is sold out.
• Massachusetts EBT and WIC cardholders pay $17 per ticket for up to four tickets.

The final-sale rule is where the zoo differs from everything else that day. The afternoon events have rain dates. A Boston Lights ticket is good for the night printed on it.

If It Rains, Sunday Gets Three Different Plans

Weather has already cost Jamaica Plain one event this fall. In September, Jamaica Plain Open Studios canceled both days because of a forecast nor'easter and said it would not reschedule. The Halloween organizers all have backup plans, but they don't match:

• Canine Costume Parade. The rain date is Sunday, Nov. 1.
• Wicked Plants. The rain date is also Nov. 1, but it shrinks to 2 to 4 p.m. The Arboretum says to check the event page for updates.
• Halloween Fiesta. There's no posted rain date. The listing says to check Hyde Square Task Force's social media for updates.
• Boston Lights. Tickets stay on the night you bought them.

So a rainy Saturday doesn't just slide everything to Sunday. The Arboretum gets a shorter afternoon, the Fiesta may or may not happen, and anyone with zoo tickets for Saturday night still has them for Saturday night.

Sunday already has an event of its own on the Arboretum calendar. Rhythms in the Garden with the Iris Percussion Quartet is listed for Nov. 1 at the Leventritt Shrub & Vine Garden. The calendar doesn't give a start time, so check the Arboretum's events page before you go. Arboretum events are free. In a dry year, it's a quiet Sunday after a long Saturday. In a wet one, it shares the Arboretum with the rescheduled Wicked Plants.

The Jamaica Pond Lantern Parade already happened, on Oct. 17. Boston Lights keeps going after Halloween weekend, with its final night on Nov. 8.

If you're out on Centre Street on the 31st, whether your dog is in costume or you're just watching, say hello. I'm always glad to talk about which blocks in Jamaica Plain are worth getting to know. Jamie Iacoi is happy to share what he hears around the neighborhood. Let's Connect.