If Dust is Flying, Keep Cover Crops in the Bag
If you are thinking about planting a cover crop, you may be worried about the dry conditions and forecast. You're not alone. Here are some things to consider as you decide how to move forward.
Cover Crop Species Matters
Some species are better suited to face fall conditions than others. However, you need to make the best decision to achieve your cover cropping priorities, taking into consideration the soil moisture conditions.
Clovers
We are now past the planting window for successful crimson, balansa, and berseem clover establishment in Pennsylvania. If you had been waiting for rain, it is time to switch species. For red clover specifically, you can wait and frost seed in late February, but only if you expect to leave the clover in until spring of 2027.
Winter-Killed Species
For species like spring oats, forage radish, buckwheat, etc., consider how much growth you'll get before the first killing frost. Is the seed and planting operation worth the expense versus how much potential forage or other benefit you'll get out of it before it dies? If you plant today and the cover crop emerges within a few days, no problem. For example, buckwheat can be ready for termination in just 40 days, while oats can be ready to bale in 60-75 days (see Fall Oats for Forage or Straw). Unfortunately, the typical quick germination we see with these species is jeopardized by the drought, so realistically, the growing window could be two weeks shorter than expected, as we wait for rain.
Winter-Hardy Species
Winter cereals, especially rye, can establish successfully even when planted in November or later. If you are looking for the nitrogen supply from a legume cover crop, hairy vetch is our most cold-tolerant option. While in the southeast, hairy vetch can still successfully be established into October, we are very close to the planting window closing further north and west. At the end of the day, cereal rye is your safest bet for successful late establishment.
Read in more detail about individual species in the Penn State Agronomy Guide Table 1.10-5 and Managing Cover Crops Profitably (PDF), or use the Northeast Cover Crop Council's Cover Crop Explorer tool to help find the best species for your situation.
| Species | Life Cycle¹ | Hardy Zone | Seeding Rate² (lb/A) | Seeding Depth (in) | Seeding Date | Nitrogen Capture / Fertilizer (lb/A) | Key Advantages | Key Disadvantages |
|---|---|---|---|---|---|---|---|---|
| Cool-Season Grasses | ||||||||
| Winter rye | WA | 3 | 30–112 | 1–2 | Sep–late Oct | Excellent N scavenger | Most cold tolerant; erosion control; weed suppression | Regrowth risk; explosive spring growth; allelopathy |
| Winter wheat | WA | 4 | 40–120 | 1–2 | Sep–mid Oct | Excellent N scavenger | Cold tolerant; rapid growth; easier to manage than rye | Lower biomass than rye; nutrient tie-up; attracts pests |
| Winter triticale | WA | 3 | 40–120 | 1–2 | Sep–late Oct | Excellent N scavenger | Intermediate between wheat and rye | Intermediate between wheat and rye; late maturity |
| Winter barley | WA | 6 | 60–120 | 1–2 | Sep | Good scavenger | Manageable height; good for southern PA | Potential winter kill; lower biomass than wheat |
| Spring oats | SA | 8 | 50–100 | 1–2 | Aug–mid Sep | Average scavenger | Easy management (winter-kills); quick fall cover | No living root in winter; high lodging potential |
| Annual ryegrass | WA | 5 | 10–20 | 0.25–0.5 | Aug–mid Sep | Good scavenger | High-quality fodder; good living cover | Difficult to control; may become a weed; low heat tolerance |
| Warm-Season Grasses | ||||||||
| Pearl millet | SA | NFT | 10–15 | 0.25–0.50 | June–July | Excellent scavenger | Drought-tolerant; heavy tillering; good forage | Very large biomass can be difficult to manage |
| Sudangrass | SA | NFT | 35–40 | 1 | June–July | Excellent scavenger | Quick growth; alleviates compaction | Prussic acid risk; large biomass management |
| Japanese millet | SA | NFT | 20–25 | 0.25–0.50 | June–July | Good scavenger | Very fast growth (4ft in 45 days); adapts to wet soils | Can become a weed; grows poorly on sandy soils |
| Legumes | ||||||||
| Hairy vetch | WA | 4 | 20–25 | 1–2 | Aug–mid Sep | 80–160 | High biomass; very cold tolerant; drought tolerant | Slow to establish; requires early fall planting; potential weed |
| Clover, crimson | WA/SA | 5 | 10–15 | 0.25–0.5 | Aug–mid Sep | 70–130 | Rapid fall growth; shade tolerant; nematode resistance | May winterkill; poor heat/drought tolerance; tough residue |
| Clover, red | SLP | 4 | 8–10 | 0.25–0.5 | Feb–June | 70–120 | Deep taproot; tolerates wet soil and shade | Slow initial growth; pure stands cause bloat in livestock |
| Field peas | SA/WA | 5 | 50–80 | 1.5–2 | Aug | 50–150 | Rapid cool-weather growth; versatile food/feed | Shallow roots; sensitive to heat and humidity |
| Cowpea | SA | NFT | 40 | 1.5–2 | June–July | 50–100 | Deep taproot for moisture; wide soil adaptation | Performance has been erratic in PA trials |
| Sunnhemp | SA | NFT | 10 | 0.5–1.5 | June–July | 0–100 | Fast growth (9ft in 60 days); reduces nematodes | No seed production in US; stems become fibrous |
| Other Crops | ||||||||
| Buckwheat | SA | NFT | 35–50 | 0.5–1.5 | June–July | Fair–Good (P, Ca) | Quick smother crop; grows on infertile/low pH soils | Frost sensitive; not winter hardy; limited biomass |
| Brassicas | WA | 8 | 5–12 | 0.25–0.5 | June–mid Aug | Good (N, P, Ca) | Compaction alleviation; quick establishment | Requires high fertility; radish leaves soil bare in spring |
1 A = annual; WA = winter annual; SA = summer annual; SLP = short-lived perennial; LLP = long-lived perennial; NFT = no frost tolerance.
2 Drilled seeding rate; for broadcast or aerial seedings or for seeding past optimum date, increase 25 to 50 percent.
3 See Table 1.10-6 for recommended fall seeding dates by small grain management area.
Seed Drills Help, But Can't Work Miracles
Understand that broadcasting cover crops without incorporation in this dry weather is bound to fail. Drilling the cover crop assures good seed to soil contact and helps seeds reach moisture as well. One detail you can change is to plant the cover crop seed a bit deeper than usual (to 2 inches deep). If you can't drill, at least follow a broadcast pass with vertical tillage or a harrow and cultipacker. But, as dry as it is now, even drilling won't help much with accessing moisture. If the seed emerges and there is no moisture, the stand could be reduced, especially on higher spots in the landscape.
Take-Home Message
If you plant seeds now and it doesn't rain for two weeks, emergence may be erratic and 3-4 weeks away. All that time, seeds are vulnerable to disease, vertebrate and invertebrate pests, and growth prior to the onset of winter will be limited.
We therefore recommend that you wait to plant until you see rain in the forecast, and at that time, only drill the most winterhardy species, such as cereal rye or winter wheat.
