When to sow sweet corn?
- Botanical name
- Zea mays
- Family
- Poaceae
Sweet corn is sown outdoors from May to June, 2.5 cm deep. It germinates in 7 days. It is harvested from August to October.
Sweet corn is an annual plant. The edible parts are the seeds.
Sweet corn through the year
- indoor sowing
- transplanting
- outdoor sowing
- harvest
In short
The last frost is not on the same day everywhere, so the recorded weeks are a guide and not a date.
Growing conditions
Companions in the bed
Companion planting is tradition and not an agronomic claim. What is recorded is which pairs sources recommend and which they advise against.
Corn and beans are part of the Three Sisters, a practice thousands of years old. The bean has to be a climbing variety and the corn tall enough beforehand.
Part of the Three Sisters: the squash covers the ground under the corn. It holds for squash in general, so for the courgette as well.
Corn and tomato share a pest, and the corn takes the tomato's sun.
- “Widely cited” means the pair is named by three or more independent sources.
- “Cited” means the pair is named by one source or two.
- “Sources disagree” means one source recommends the pair and another advises against it.
Pests and diseases
Listed here is every problem for which the sources name this plant as a host. The problems are not listed in order of how common they are.
European corn borer
pest- Signs
- Small entry holes in the stem with borings that look like sawdust. Above them the foliage wilts or the stem snaps. The caterpillar feeds inside the cob as well.
- Prevention
- In autumn remove or shred the stems in which the caterpillars overwinter: cut them off at ground level and mulch them, plough them in or carry them off the bed. This is the strongest measure, because it takes the pest's winter quarters away.
- What to do
- Split the attacked stem below the entry hole and destroy the caterpillar. On a small bed this is workable and more precise than spraying, which does not reach a caterpillar inside a stem anyway.
Flea beetles
pest- Signs
- The leaves are riddled with small round holes, as if somebody had peppered them with shot. Touched, the beetles jump. Young plants with such leaves stall or die, older ones grow through the damage.
- Prevention
- Clear away the plant debris in which the beetles overwinter. Cover the bed with fleece right after sowing or planting and leave it until the plants are strong. Keep the soil moist, because a dry warm spring is the worst case.
- What to do
- Pin fleece down at the edges, which is the main measure. In autumn or early spring loosen the top layer of soil to cut down the number of overwintering beetles.
Keep track of your plants with Tendask
Log the task and set a reminder for the next one. Every plant keeps its own history, so there is nothing to guess at.
Sources about the plant: Clemson Cooperative Extension, GBIF Backbone Taxonomy, KGZS Zavod Ljubljana, KGZS Zavod Nova Gorica, NC State Extension Plant Toolbox, Royal Horticultural Society, Semenarna Ljubljana, Smernice za strokovno utemeljeno gnojenje (Mihelič et al., MKGP 2011), University of Georgia Extension, University of Illinois Extension, University of Maryland Extension, Utah State University Extension, Wikidata. Checked between 14 and 26 August 2026. The problem descriptions also draw on: EPPO Global Database.