Choosing the Right Cover Crop Mix:
Lessons from a 2026 Field Demonstration
Cover crops can be a valuable part of vegetable rotation. They keep the
soil covered between cash crops, capture nutrients, add plant residue, compete
with weeds, and provide different types of roots that can help improve soil
structure and resilience over time.
There is no single cover crop mix that is best for every situation. The
right choice depends on when the cover crop is planted, how long it will be
allowed to grow, and what the grower wants it to accomplish.
In June 2026, six different cover crop mixtures were planted at the
Perennia Field House. The mixtures included different combinations of oats,
sorghum-Sudan grass, pearl millet, forage peas, crimson clover, radish, and
sunflower. The demonstration was established to see how different mixtures
perform and what practical benefits they may offer vegetable growers.
Benefits of Multispecies Cover Crop
Blends
Multispecies cover crop blends can provide several benefits by combining
plants with different functions. Grasses can produce biomass and extensive
fibrous roots, legumes can contribute nitrogen through biological nitrogen
fixation, and broadleaf species can provide different rooting patterns and add
diversity.
In this demonstration, the six-species mixture of oats, forage peas,
crimson clover, sorghum-Sudan grass, radish, and sunflower produced the highest
biomass at the first cutting. A simpler mixture of pearl millet and forage peas
also produced good biomass.
These observations show that there are different ways to build an
effective cover crop mixture. The important consideration is to select species
that provide the desired benefits and are reasonably well matched to the
planting window and growing period.
Figure 1. Six-species cover crop mixture was planted on
June 10, 2026. Photo taken on August 12, 2026 (63 days after planting).
Figure 2. Pearl millet and black forage
peas planted on June 10, 2026. Photo taken on August 12, 2026 (63 days after
planting).
Match the Species to the Planting
Window
One of the most useful lessons from this demonstration was that species
within a multispecies blend can have different temperature requirements, growth
rates, and maturity dates.
Oats, for example, established quickly when planted in June but also
matured quickly. This creates important management consideration in a
multispecies blend. If oats begin producing seed while other species are still
actively growing, the entire cover crop mixture may need to be mowed or
terminated to prevent viable seed production. This can shorten the growing
period for later-maturing species and reduce some of the benefits expected from
those species.
Planting season is also important. Oats, radish, and
crimson clover generally perform better under cooler conditions, particularly
during establishment. In the Annapolis Valley, oats and clovers are better
suited to late April and May planting, while radish is generally better suited
to August and September planting. When these species are planted during hot
summer conditions in June and July, establishment and growth may be reduced. In
contrast, warm-season grasses such as sorghum-Sudan grass and pearl millet are
better adapted to June and July planting and can produce substantial
above-ground growth and extensive root systems.
Figure 3. Sorghum-Sudan grass and black
forage pea mixture planted on June 10, 2026. Photo taken on August 12, 2026 (63
days after planting), showing the strong growth and height of sorghum-Sudan
grass under summer growing conditions.
Think Below Ground Too
It is easy to judge a cover crop by what we can see above the soil, but
much of its important work is happening underground.
Grasses such as sorghum-Sudan grass and pearl millet produce extensive
fibrous root systems. These roots explore the soil and help hold soil particles
together. Maintaining living roots and returning plant residues can support
soil structure and resilience over time.
Another useful characteristic of these warm-season grasses is their
ability to regrow after mowing. If sorghum-Sudan grass and pearl millet are
mowed high enough, leaving approximately 8–10 inches of stubble, they can
regrow when adequate growing conditions remain. This can provide additional
biomass, maintain living roots and soil cover, continue nutrient uptake, and
help compete with weeds later in the season.
Figure 3: Dense fibrous roots of sorghum-Sudan grass after mowing show
how the root system can bind and hold soil together.
What Should Growers Take from This?
The main lesson from the first year of this demonstration is to start
with the goal and planting window and then select species that can work well
together.
Multispecies blends can provide several functions within the same cover
crop, including biomass production, nitrogen fixation, nutrient capture, weed
competition, and different rooting patterns. However, species in the mixture
should be selected with their growing-season preference and maturity in mind.
For summer planting, warm-season species such as sorghum-Sudan grass and
pearl millet can be useful components of a mixture. Species such as oats, radish, and
clovers can grow during summer; however, establishment may be reduced when
seeded during hot, dry periods in July and August. They generally establish
better and provide greater benefits when planted during periods of moderate
temperatures, such as in May or from early August to early September in the
Annapolis Valley of Nova Scotia.
Maturity is another important consideration. If one species reaches seed
production well ahead of the others, the whole mixture may need to be mowed or
terminated earlier than planned to prevent volunteer or weed problems.
Selecting species with compatible growth periods can help growers capture more
of the intended benefits from the entire mixture.
The key is not simply how many species are in the blend, but how well
those species work together within the available planting and growing window.
The demonstration will continue to evaluate regrowth, rooting, nutrient
cycling, and soil-health indicators to better understand how these cover crop
strategies can support vegetable production under Nova Scotia conditions.
Manphool Fageria, PhD, P.Ag.
Vegetable Specialist | Agricultural Services
Perennia Food and Agriculture Corporation
Email mfageria@perennia.ca
Mobile
902-890-7716
6-28 Aberdeen Street, Kentville, NS B4N 2N1
