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When to Plant Begonias in Grimes County, TX

Grimes County, Texas Zone 9a August

Top priorities for Grimes County, Texas gardeners in August

We've pulled the most time-sensitive tasks for Grimes County, Texas this August and put them front and centre. Tackle them in order.

Avg. last frost February 25
Avg. first frost December 1
Soil temp (4") 93°F
Watering Low
Pest pressure High
Daylight 13.1 hrs
  1. It's harvest week for begonias

    This is the payoff month. Bring a basket, bring a friend, and get into the beds.

To set up a strong September, finish these tasks
  • First harvests: begonias

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Wax begonias (Begonia × semperflorens) are the workhorse shade bedding plant of American horticulture, offering continuous bloom from transplant to hard frost. Bronze or green-leaved varieties perform well from deep shade to full sun (in northern zones) and tolerate summer humidity better than most cool- season flowers. A staple of mass plantings, containers, and window boxes.

Grimes County, Texas is in USDA Zone 9a. The average last spring frost is February 25 and the first fall frost is December 1, giving you a growing season of approximately 279 days.

At an elevation of 33 feet, Grimes County receives approximately 65.2 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 91°F, providing good warmth for Begonias during the growing season. Sandy soil warms quickly in spring — great for early planting — but Begonias will need more frequent watering and organic matter to retain nutrients. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Begonias root diseases.

Annual Blooms in Multi-season Pollinator-friendly Deer-resistant
Grimes County, TX (Zone 9a) Year-round
279 days
Last Spring Frost February 25
279 growing days
First Fall Frost December 1

Grimes County Soil Profile

Soil Type

Sandy Loam

Soil pH

5.8-6.5

Drainage

Well Drained

Begonias Planting Risk Windows

Early Start (70% safe) ✓ Fits season (52 days to spare)
Start indoors: Dec 4 Transplant: Jan 22 🌸 Bloom: Apr 2 – Oct 1
Recommended (50%) ✓ Fits season (48 days to spare)
Start indoors: Dec 17 Transplant: Feb 4 🌸 Bloom: Apr 15 – Oct 14
Safe Start (90%) ✓ Fits season (51 days to spare)
Start indoors: Dec 31 Transplant: Feb 18 🌸 Bloom: Apr 29 – Oct 28

Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.

Soil Compatibility in Grimes County

How your county's soil matches Begonias's growing requirements.

Soil pH

Your soil pH (5.8–6.5) is within Begonias's preferred range (5.5–6.5).

Soil Texture

Sandy soil in Grimes County warms quickly in spring but drains fast. Begonias will need more frequent watering and regular compost additions to retain nutrients.

Drainage

Drainage is adequate for Begonias.

Organic Matter

Organic matter is low (1.7%). Add 2-3 inches of compost before planting Begonias.

How to Plant Begonias

8"
Between Plants
10"
Between Rows

Succession Planting Begonias

4
successive plantings in your 279-day season

Sow every 8 weeks. Last sowing by Sep 02 to harvest before frost.

Begonias Water Budget

Plant needs
1.0″/week
Rainfall provides
1.0″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 963 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Begonias

Begonias needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Begonias Needs Rainfall You Supplement Action
Jan 1.9" 0" ❄️ Dormant
Feb 4.3" 2.1" 2.2" 🚿 Regular watering
Mar 4.3" 4.7" 0" ✅ Rainfall sufficient
Apr 4.3" 6" 0" ✅ Rainfall sufficient
May 4.3" 9.9" 0" ✅ Rainfall sufficient
Jun 4.3" 9.9" 0" ✅ Rainfall sufficient
Jul 4.3" 8.3" 0" ✅ Rainfall sufficient
Aug 4.3" 8.3" 0" ✅ Rainfall sufficient
Sep 4.3" 6.6" 0" ✅ Rainfall sufficient
Oct 4.3" 3.9" 0.4" 💧 Light watering
Nov 4.3" 2" 2.3" 🚿 Regular watering
Dec 4.3" 1.7" 2.6" 🚿 Regular watering

Water needs are for active growing months only (Feb–Dec in Grimes County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Begonias Heat Requirements (GDD)

What are Growing Degree Days (GDD)?

Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.

Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.

Begonias needs ~1,460 GDD — county provides 5,110 GDD Excellent fit

Begonias Planting Timeline — Grimes County, TX

Begonias Planting Calendar

Activity When Date Range
Start Indoors December 17 Dec 17 – Dec 31
Transplant Outdoors February 4 Feb 4 – Feb 18
Bloom April 15 Apr 15 – Oct 14

· 8" apart · Rows 10" apart

Month-by-Month Timeline

MonthActivities
January
February Transplant Outdoors
March
April Bloom
May Bloom
June Bloom
July Bloom
August Bloom
September Bloom
October Bloom
November
December Start Indoors

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

70–90 days

🧪 Soil pH

Needs 5.5–6.5 · Your soil: ideal

🗺️ USDA Zone

Zone 9a

📆 Growing Season

279 days in Grimes County

Growing Tips for Begonias in Grimes County

Direct sow Begonias outdoors after February 25 in Grimes County when soil has warmed and frost danger has passed.

Sandy soil in Grimes County dries quickly — mulch Begonias with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.

General growing tips

Start seeds indoors 10–12 weeks before last frost — seed is dust-fine; surface-sow on moist mix under lights, do not cover. Bottom heat (70–75°F) speeds germination. Transplant after frost; begonias are not direct-sown in practice. Pinch seedlings once for branching. Keep soil evenly moist; avoid waterlogged conditions. Bronze-leaf types tolerate more sun; green- leaf types prefer shade to part-sun.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Begonias in Grimes County, TX?

Grimes County is in Zone 9a with an average last frost of February 25. Plan your Begonias planting based on this frost date — see the calendar above for exact timing.

What planting zone is Grimes County, TX?

Grimes County, Texas is in USDA Hardiness Zone 9a. The average last spring frost is February 25 and first fall frost is December 1.

🌱

Your Grimes County Garden Planner — Free

A 22-page printable planner built for Grimes County (Zone 9a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Grimes County, TX. Local conditions may vary. Last updated: August 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.