Beat first frost: raised beds, real dates, real pairings

Your garden club has probably told you to tuck marigolds next to your potatoes to keep the Colorado potato beetle away. That one does not hold up.

Multiple studies show the marigold-potato pairing does not work, per the Farmers Almanac's companion planting guide, which draws on University of Minnesota Extension research. Below: the pairings that actually work, plus your real frost dates, not the ones on the seed packet.

The pairings that actually earn their spot

If marigolds and potatoes are out, what is in? University of Minnesota Extension backs four pairings with real results, per the same companion planting guide:

• Tomato with basil
• Brassicas with thyme
• Squash with nasturtium
• Corn with buckwheat

These are not folklore. Researchers tested them and they work. If you have room for one experiment before frost, make it one of these four instead of the marigold bed everyone's grandmother swears by.

Tomato and basil share a bed happily. Marigolds and potatoes never got the memo.

Your seed packet does not know your zip code

Frost dates are not one number for your whole state, and folklore does not know your zip code. Take Texas, which spans USDA zones 6 through 9.

The 2026 last-frost dates swing from as early as February 1 in Corpus Christi (zone 9) to as late as March 24 in El Paso (zone 8), according to Fox4's 2026 Texas planting guide. Even that range carries a stated 10 percent chance frost falls outside the window on either end, the difference between transplants that make it and a wasted flat of seedlings.

In zone 7, your last frost typically lands in mid-April, pushing as late as the first week of May in a rough year. First frost in fall typically lands in mid-October, occasionally sliding to early November, per LoveToKnow's zone 7 gardening guide. That six-month window is your real planning tool, not a date on a seed packet from a company that has never seen your yard.

Ten percent of the time, frost ignores the calendar completely.

The raised bed math beats the vibes

We hear "get a raised bed" a lot, without anyone explaining why or how much soil it takes. Raised beds drain better than in-ground soil, warm up faster in spring, and sidestep hard clay or fast-draining sand, which is why they work for beginners and veterans alike, per HGTV's raised bed guide.

Here is the part nobody gives you a number for. A frame-free raised bed needs about 6 inches of piled soil to get going. A framed bed at 4 feet by 8 feet and 8 inches deep needs roughly 21.44 cubic feet of soil, per the same HGTV guide. That is a real number for the garden center, not "a truckload" or "however much looks right."

A framed 4x8 bed eats about 21.44 cubic feet of soil before it is full.

Bottom line

• Marigolds do not repel potato beetles. Plant tomato with basil, brassicas with thyme, squash with nasturtium, or corn with buckwheat instead, per Farmers Almanac.
• Your real frost date depends on your specific zone, not your state. Texas alone spans zones 6 through 9, with last frost ranging from February 1 to March 24, per Fox4.
• Raised beds drain better and warm up faster than in-ground soil, per HGTV.
• A framed 4 by 8 foot bed at 8 inches deep needs about 21.44 cubic feet of soil, per the same HGTV guide.

Your zone

Zone 3-4: [VERIFY: no zone 3-4 specific frost-date source opened this pass]

Zone 5-6: You get a standard two-season window: direct sow cool crops in spring and again in late summer for a fall harvest. In Texas zone 6, covering the Panhandle including Amarillo, start beets, broccoli, cauliflower, kale, lettuce, onions, peas, and spinach indoors in March, per Fox4's Texas planting guide.

Zone 7-8: Long shoulder seasons mean you can pull a spring and a fall crop of the same vegetable. Zone 7 runs roughly mid-April to mid-October frost-free, about six months, per LoveToKnow. In Texas zone 8, covering Austin, El Paso, Tyler, and parts of Houston and San Antonio, last frost can arrive as early as February 17, per Fox4.

Zone 9-10: Mild winters let you grow cool crops right through them, but watch for summer heat stress on spring transplants. Corpus Christi, Texas, zone 9, can see its last frost as early as February 1, per Fox4.

Zone 11+: [VERIFY: no zone 11+ specific source opened this pass]

Sources

1. HGTV, raised bed vegetable garden tips
2. Fox4, when to start planting Texas vegetables in 2026
3. LoveToKnow, gardening zone 7 guide
4. Farmers Almanac, companion planting guide Photo: 2021-11-06 15 02 50 Tomato plants killed by frost along Old Dairy Court in the Franklin Farm section of Oak Hill, Fairfax County, Virginia by Famartin, CC BY-SA 4.0, via Wikimedia Commons, https://commons.wikimedia.org/wiki/File%3A2021-11-06_15_02_50_Tomato_plants_killed_by_frost_along_Old_Dairy_Court_in_the_Franklin_Farm_section_of_Oak_Hill%2C_Fairfax_County%2C_Virginia.jpg Photo: Frost leaves 1b by NeilK, CC BY-SA 3.0, via Wikimedia Commons, https://commons.wikimedia.org/wiki/File:Frost_leaves_1b.jpg Photo: Red leaves wih frost, Ehrenbach by Gerda Arendt, CC0, via Wikimedia Commons, https://commons.wikimedia.org/wiki/File:Red_leaves_wih_frost,_Ehrenbach.jpg Photo: Field with frost on leaves, Ehrenbach by Gerda Arendt, CC0, via Wikimedia Commons, https://commons.wikimedia.org/wiki/File:Field_with_frost_on_leaves,_Ehrenbach.jpg