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Tri-X 313 Seedless Watermelon

Cucurbitaceae

Tri-X 313 is a seedless (triploid) watermelon listed in the Texas A&M AgriLife seedless crop guide, which gives 65 to 75 days from planting to harvest. Seedless watermelons still need pollen to set fruit, so plant a standard seeded variety of a different color or shape alongside as the pollinizer. Key facts: 65–75 days to maturity from planting, 24–36" spacing.

Updated September 11, 2026 · Backed by 3 cited sources
Overview

At a Glance

The essentials first: timing, light, spacing, seed-starting, container fit, and overall size.

Days to maturity
65–75 days
from planting
Spacing
24–36"
between plants
Planting window

Zone Planting Guide

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Care

Growing Guide

Everything in one place: seed starting, transplant timing, watering, soil, and structural support.

Moisture
Watering
Weekly1"
Root zone
Soil
pH range5.5–8
Common questions

Watermelon (Tri-X 313) FAQ

Every answer is assembled from this cultivar's own record, so the figures match the rest of the page.

How many days to maturity for Tri-X 313 Seedless Watermelon?

Watermelon (Tri-X 313) takes 65–75 days to reach maturity from planting.

How far apart should you plant Tri-X 313 Seedless Watermelon?

Space Watermelon (Tri-X 313) 24–36 inches apart, with 80 inches between rows.

How much water do Tri-X 313 Seedless Watermelon need?

Watermelon (Tri-X 313) needs 1 inches of water a week, counting rainfall.

What soil pH do Tri-X 313 Seedless Watermelon need?

Watermelon (Tri-X 313) grows best in soil with a pH of 5.5–8.

How do you start Tri-X 313 Seedless Watermelon from seed?

Start seed indoors.

When is Tri-X 313 Seedless Watermelon in season?

Watermelon (Tri-X 313) is a warm-season crop, in season from mid-summer through fall in most regions. Plants reach harvest 65–75 days after planting and keep producing until the first fall frost.

Feeding & picking

Nutrition & Harvest

How hungry the plant is, what ripe harvest looks like, and how long the crop keeps after picking.

Timing
Harvest

Harvest 65 to 75 days after planting.

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What you'll need

Growing Supplies

Hand-picked for your Watermelon (Tri-X 313), with the extension research behind every recommendation.

Seed starting tray + heat mat

For crops started indoors before transplanting, this tray-and-mat combo improves germination consistency. Bottom heat speeds and evens germination; warm-season crops in particular want it, while cool-season transplants germinate fine at the lower end of the range. Look for a rigid tray, cell inserts with drainage, and a mat paired with a thermostat.

Source: Utah State University Extension; Iowa State University Extension; Mississippi State University Extension

Our pick

Seedling Heat Mat + Thermostat Combo

Same trusted mat with a digital thermostat so you can dial in exact soil temperature. Peppers want 80-85°F, tomatoes 75-80°F.

paid link ?When you shop on Amazon using this link, SoilStack earns a small commission at no extra cost to you. It's how we keep the site free and the calendar ad-free. Every product on this page was hand-selected based on university extension research. When you shop on Amazon using this link, SoilStack earns a small commission at no extra cost to you. It's how we keep the site free and the calendar ad-free. Every product on this page was hand-selected based on university extension research.
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Mulch / landscape fabric

Nearly every garden benefits from mulch for weed suppression, moisture conservation, and soil temperature moderation. For most home gardeners, quality organic mulch is the better buy over landscape fabric.

Source: Penn State Extension; Wisconsin Horticulture; Illinois Extension

Our pick

Cleaned Wheat Straw Mulch (3 cu ft, ~20 lbs)

Thoroughly cleaned wheat straw at 3 cubic feet, marketed specifically for vegetable gardens rather than animal bedding or decoration. Better per-pound economics than the 1 cu ft option, with the same extension-recommended material. Strong sales volume (2K+ bought past month) supports product consistency.

paid link ?When you shop on Amazon using this link, SoilStack earns a small commission at no extra cost to you. It's how we keep the site free and the calendar ad-free. Every product on this page was hand-selected based on university extension research. When you shop on Amazon using this link, SoilStack earns a small commission at no extra cost to you. It's how we keep the site free and the calendar ad-free. Every product on this page was hand-selected based on university extension research.
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Drip irrigation / soaker hose kit

Every gardener benefits from putting water at the root zone instead of on the leaves, because drip and soaker systems reduce foliar disease pressure by limiting leaf wetness and soil splash. A quality kit should include a backflow preventer, filter, pressure reducer, and UV-resistant tubing.

Source: Iowa State University Extension; Colorado State University Extension; UMass Extension

Our pick

Complete Garden Drip Irrigation Kit

Designed for beginners with a step-by-step setup guide. Adjustable emitters, both tubing sizes, and all connectors included.

paid link ?When you shop on Amazon using this link, SoilStack earns a small commission at no extra cost to you. It's how we keep the site free and the calendar ad-free. Every product on this page was hand-selected based on university extension research. When you shop on Amazon using this link, SoilStack earns a small commission at no extra cost to you. It's how we keep the site free and the calendar ad-free. Every product on this page was hand-selected based on university extension research.
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Row cover / frost blanket

Row cover adds frost protection, speeds early growth, and physically excludes insect pests without spraying. Look for spun-bonded fabric with a stated weight and frost rating, UV resistance, and enough width for hoops or low tunnels.

Source: University of Maryland Extension; University of New Hampshire Extension; Colorado State University Extension

Our pick

Frost Blanket (10'x30')

Thicker 1.2 oz fabric rated to protect down to 28°F. Covers 300 sq ft — enough for multiple raised beds in a single sheet.

paid link ?When you shop on Amazon using this link, SoilStack earns a small commission at no extra cost to you. It's how we keep the site free and the calendar ad-free. Every product on this page was hand-selected based on university extension research. When you shop on Amazon using this link, SoilStack earns a small commission at no extra cost to you. It's how we keep the site free and the calendar ad-free. Every product on this page was hand-selected based on university extension research.
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Internal links

Tri-X 313 Seedless Watermelon Planting Dates by Zone

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