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SUS Farms · Sevier County, Utah
Utah Growing Reference
Synthesized from USU Extension Yard & Garden, Utah Climate Center, and on-farm logs.
Last-frost / first-frost by city
| City | Elev. | USDA Zone | Last spring frost | First fall frost |
|---|---|---|---|---|
| St. George | 2,860 ft | 8a | Mar 25 | Nov 5 |
| Hurricane | 3,258 ft | 7b | Apr 5 | Oct 28 |
| Cedar City | 5,846 ft | 6a | May 22 | Sep 28 |
| Richfield | 5,341 ft | 6a | May 18 | Oct 1 |
| Sevier County (SUS) | 5,400 ft | 6a | May 15 | Oct 5 |
| Salt Lake City | 4,226 ft | 7a | Apr 26 | Oct 22 |
| Sandy | 4,470 ft | 7a | May 1 | Oct 18 |
| Provo | 4,551 ft | 6b | May 5 | Oct 12 |
| Logan | 4,534 ft | 5b | May 22 | Sep 30 |
| Park City | 7,000 ft | 5a | Jun 15 | Sep 5 |
| Vernal | 5,331 ft | 5b | May 28 | Sep 22 |
| Moab | 4,026 ft | 7a | Apr 22 | Oct 24 |
Ideal soil pH by crop · Utah native: 7.4–8.4
| Crop | Ideal pH | Verdict | Note |
|---|---|---|---|
| Blueberries | 4.5–5.5 | ✗ Needs amendment | Effectively impossible in native Utah soil — grow in raised beds with peat-based mix. |
| Potatoes | 5–6.5 | ✗ Needs amendment | Lower pH suppresses scab. Sulfur amendment recommended. |
| Strawberries | 5.5–6.8 | ✗ Needs amendment | Acidify with elemental sulfur 6 months before planting. |
| Raspberries | 5.6–6.5 | ✗ Needs amendment | Will tolerate up to 7.0 with regular iron applications. |
| Tomatoes | 6–6.8 | ✗ Needs amendment | Surprisingly adaptable but iron deficiency shows yellow-veined leaves above 7.5. |
| Peppers | 6–6.8 | ✗ Needs amendment | Same iron concerns as tomatoes — both are Solanaceae. |
| Corn | 5.8–7 | ✗ Needs amendment | Tolerant. Most Utah soils grow good corn without amendment. |
| Cucurbits | 6–7.5 | ✓ Tolerates Utah pH | Among the most tolerant of native pH — squash and melons grow well untouched. |
| Brassicas | 6–7.5 | ✓ Tolerates Utah pH | Native Utah pH is fine. Boron deficiency more often the issue. |
| Asparagus | 6.5–7.5 | ✓ Tolerates Utah pH | One of few crops that thrives in Utah pH untouched. |
| Most lawns | 6–7.5 | ✓ Tolerates Utah pH | Fescue and bluegrass are pH-tolerant. Iron chlorosis comes from compaction more than pH. |
Soil amendments · per 100 sq ft
| Amendment | Rate | When | Why |
|---|---|---|---|
| Compost (annual top-dress) | 1–2 inches | Late fall or early spring | Builds organic matter, holds water, feeds soil biology. |
| Elemental sulfur | 1 lb / 100 sq ft | 6+ months before planting | Lowers pH 0.5 unit. Repeat applications needed for stubborn caliche soils. |
| Aged manure | 0.5–1 inch | Fall (must age before planting) | Nitrogen and biology. Never use fresh — burns roots and may carry weed seed. |
| Iron chelate (Sequestrene 138) | Per label, foliar | When chlorosis appears | Quickest fix for iron-deficiency yellowing in alkaline soil. |
| Gypsum | 5 lb / 100 sq ft | Anytime | Loosens clay-caliche soils. Does NOT lower pH despite the myth. |
| Cover crop (rye/vetch mix) | 2 oz / 100 sq ft | Sow Sept, terminate April | Adds organic matter and fixes nitrogen over winter. Best long-term play. |
Raised bed mix · 48" × 12"
50%
Topsoil
30%
Compost
10%
Sand or perlite
10%
Peat or coir
Edging: Untreated cedar or redwood. Avoid pressure-treated lumber and railroad ties — both leach into food crops.
Watering: Drip line at the surface, mulch 2" deep on top.
Pest calendar (USU IPM)
Mar
- • Codling moth (set traps)
- • Cabbage maggot
Pheromone traps in apples; row cover on brassicas.
Apr
- • Aphid pressure starts
- • Cherry slug
- • Powdery mildew (early)
Beneficial release; horticultural oil dormant spray on stone fruit.
May
- • Cucumber beetle
- • Flea beetle on eggplants/potatoes
Floating row cover until flowering; trap crops.
Jun
- • Squash bug
- • Squash vine borer (lower elevations)
- • Spider mite (heat)
Hand-pick squash bug eggs; mist undersides of leaves daily for mites.
Jul
- • Tomato hornworm
- • Earwig surge after irrigation
- • Powdery mildew on cucurbits
Bt for hornworms; trap earwigs with rolled newspaper; spaced plantings.
Aug
- • Grasshoppers (variable years)
- • Late blight on tomatoes (wet years)
Nolo bait; remove infected tomato leaves.
Sep
- • Codling moth second flight
- • Vole damage starts
Pick up dropped fruit; clear weeds from tree bases.
Oct
- • Mouse / vole prep
Mouse-proof tree guards; clean compost piles.