USDA Zone 13

Average annual extreme minimum temperature: 60 to 70°F

This page is written with an honest limit in mind: most of what this site recommends for a typical vegetable garden was never going to hold up in a climate this extreme, and pretending otherwise wouldn't serve anyone actually gardening here. It's the hottest, most consistently tropical band the USDA's 2023 Plant Hardiness Zone Map defines - 60 to 70 degrees Fahrenheit average extreme minimum winter temperature - and in US territory it's limited to a handful of the lowest, most sheltered coastal lowlands of Puerto Rico, the very warmest pocket of Hawaii's Kona coast, and Guam.

This Is the Edge of What a Temperate Crop List Covers

Most of this site is built around crops with real temperate-climate roots - even the ones that tolerate heat well were bred and selected in growing regions with at least some seasonal variation. Zone 13's constant, extreme warmth pushes past what a lot of that breeding assumes, so results here are genuinely more variable and experimental than on any other zone page on this site, even compared to Zone 12 just below it.

What Has the Best Realistic Chance

Sweet potatoes and okra are the two crops on this site's list most likely to perform reliably in Zone 13 - both are genuine heat-adapted crops with a wide tolerance for sustained extreme warmth and humidity. Southern peas are a reasonable third choice for the same reason. Beyond these three, treat everything else on this site's crop list as a real experiment rather than an expected outcome, and watch the specific plant's response rather than assuming a guide written with a milder zone in mind will translate directly.

Even Heat-Lovers Can Struggle at the Extreme

Sustained daytime highs in the 90s paired with high humidity and warm nights can push even genuinely heat-tolerant crops like peppers and okra into blossom drop or reduced fruit set during the hottest stretches of the year - a real limit distinct from the milder heat stress described on this site's other warm-zone pages. Some Zone 13 growers use shade cloth during the most extreme weeks specifically to protect fruit set on crops that would need no such protection in a less extreme zone, treating shade as a heat-management tool rather than something reserved for shade-loving crops.

Guam's Typhoon Season Is a Different Calendar Than Hurricane Season

Guam sits in the western Pacific typhoon belt, which runs on a different rhythm than the Atlantic hurricane season affecting Puerto Rico - Pacific typhoon risk is present across more of the year, with a less sharply defined peak season, which means the storm-preparedness habits described elsewhere on this site (low, wind-tolerant crops, quick-securing trellises, harvesting ahead of a forecast storm) need to be closer to a year-round default in Guam rather than a seasonal precaution limited to a few months.

A Working Approach, Not a Planting Calendar

Build the garden around sweet potatoes, okra, and southern peas first - keep them going continuously rather than trying to fit them into a seasonal schedule they don't need.
Grow peppers cautiously, in a disease-resistant variety, with shade cloth available for the hottest stretches to protect fruit set.
Avoid lettuce, spinach, peas, and most brassicas outright rather than searching for a workable window - none exists in this zone's constant heat.
In Guam specifically, keep wind-resilience practices (low profiles, securable trellising, early harvest ahead of a storm) in place year-round rather than seasonally.

Garlic Is Not a Realistic Crop Here

Even the pre-chilling workaround described for Zone 11 and Zone 12 is a harder sell in Zone 13, since the gap between this zone's constant extreme warmth and garlic's cold requirement is at its widest here of any zone this site covers. Growers who specifically want garlic in this zone should expect to rely entirely on refrigerated cloves and treat the result as uncertain rather than counting on it.

Drainage and Airflow Still Apply

The same tropical-rainfall drainage concerns described for Zone 12 apply here too, often more intensely - a raised bed with a genuinely well-draining mix, sited to avoid standing water, is a baseline requirement rather than an improvement. Spacing every crop generously for airflow matters as much here as anywhere on this site, since fungal disease pressure under constant heat and humidity doesn't ease at any point in the year.

Why Publish a Page for a Zone This Narrow

It would be easy to skip a genuinely marginal zone like this one entirely, but a handful of real gardeners do live and grow food in Zone 13, and they deserve an honest answer rather than silence or a guide that quietly assumes conditions this zone doesn't have. The goal of this page isn't to make Zone 13 sound like every other zone with the numbers swapped - it's to say clearly which small part of this site's crop list has a real chance here, and to be upfront about the rest.

A Note on Elevation Within the Zone

Because Zone 13 describes such an extreme, narrow band of conditions, even a modest gain in elevation on Puerto Rico, Hawaii, or Guam can shift a specific property into a meaningfully cooler zone with a genuinely wider crop list available. A grower right at the edge of this zone's boundary, even a short drive from the coast, may find that checking their exact location against the current USDA map opens up crops this page has to rule out for the zone's hottest, lowest-elevation core.

Where Zone 13 Falls

Zone 13 is the rarest and smallest zone this site covers, limited to specific coastal lowlands of Puerto Rico, the warmest pocket of Hawaii's Kona coast, and Guam. Move to any meaningful elevation on any of these islands and the picture changes fast - your actual growing zone is very likely cooler and considerably friendlier to this site's broader crop list, so it's worth looking up your specific address rather than assuming an entire island shares this page's extremes.

Companion Planting Is the Same Across Zones

Even with a crop list this short, sweet potatoes, okra, and southern peas still have real companion and antagonist relationships worth checking before you decide what goes where - a narrow list doesn't mean the layout question disappears, it just means fewer combinations to weigh.

Look up your frost dates →Build a planting calendar →

Frequently Asked Questions

Is it worth trying tomatoes in Zone 13 at all?

It's a genuine long shot rather than a reliable plan - sustained extreme heat and humidity here push well past what tomatoes typically tolerate well, and even the disease-resistant varieties that help in a milder tropical zone face a tougher environment in Zone 13's constant extreme warmth.

Does it matter that nighttime temperatures barely drop in Zone 13, or is daytime heat the only real concern?

Warm nights are a real, separate stress on top of daytime heat - many plants use cooler nighttime temperatures to recover from daytime heat stress and properly set fruit, and Zone 13's minimum average winter temperature alone, 60 to 70 degrees Fahrenheit, is warmer than the daytime high in plenty of temperate zones this site covers. That lack of nighttime relief is part of why even genuinely heat-tolerant crops can underperform here in ways a simple daytime-heat number wouldn't fully explain.

How much more often does a Zone 13 garden need watering compared to a milder zone on this site?

Meaningfully more - constant high heat and humidity drive faster soil-moisture loss even with regular tropical rain, and a raised bed's lighter, well-draining mix, needed here for drainage, also dries faster than denser native soil would. Daily checking during the driest stretches, rather than the every-few-days schedule that works in a temperate zone, is closer to the realistic baseline here.