Houston, TX

Houston sits in zone 9b, where winter lows rarely drop below 25 to 30°F. The city's defining advantage is its exceptionally long growing season: from a last spring frost around February 13 to a first fall frost around December 9. That spans roughly 300 frost-free days, among the longest in the continental United States.

The constraint isn't cold. It's heat and humidity. Summers routinely exceed 95°F, and coastal humidity means mold, mildew, and fungal pressure remain high from late spring through early fall. This is why figs, pomegranates, Asian persimmons, and jujubes thrive where they might struggle in cooler zones: they tolerate and even prefer the heat. Warm-season vegetables like tomatoes, peppers, and okra find ideal conditions from April through November, with potential for two or even three plantings across the year.

The trade-off is a spring spike in disease pressure. February and March warmth can trigger leaf unfurling before the risk of freeze has actually passed. A late frost in mid-March can kill new growth on tender ornamentals and early-planted vegetables, even though the season is long overall. Experienced gardeners in this region don't race the calendar in February: they wait until mid-March before putting sensitive crops in the ground.

Late spring frosts are the most common single threat. The combination of an early, warm February followed by a cold snap in March catches home gardeners off guard. Even though full-season frost risk is minimal, that one unexpected March freeze can destroy tender new foliage on fruit trees and set back newly planted vegetable transplants by weeks.

Humidity-driven fungal disease is relentless. Powdery mildew hits ornamentals, roses, and some vegetables (particularly squash and peppers) starting in late summer. Anthracnose affects stone fruits and some shade trees. Extended wet springs favor bacterial leaf spot and other pathogenic fungi. Proper spacing, selecting resistant varieties, and staying alert to early symptoms are essential.

Finally, summer heat itself can cause problems. While most crops suited to this region handle heat well, beans and some cool-season vegetables suffer blossom drop in extreme heat (above 95°F at night), and newly planted specimens can stress without consistent irrigation.

Wait until mid-March to plant tender annuals, even though frost risk is technically past mid-February. The later planting date avoids damage from the periodic cold snap that appears between February and March, and it costs almost nothing since the long growing season means those plants still mature well before December.

Select disease-resistant or disease-tolerant varieties. For tomatoes and peppers, prioritize varieties bred or tested in humid Southeast and Gulf conditions rather than generic catalogs. For ornamentals and shade trees, research mildew and anthracnose resistance ratings before buying.

Succession plant warm-season vegetables every three to four weeks from late March through August. The long season allows multiple harvests of tomatoes, peppers, and okra without a single planting. Stagger plantings to maintain production through the heat and into fall, when temperatures moderate enough for a fall tomato crop in October and November.