When to Plant Nasturtium
Planting Window
- Direct sow
- After frost risk has passed
| USDA Zone | Typical Window |
|---|---|
| Zone 5 and colder | Late May to early June |
| Zone 6-7 | Mid-May |
| Zone 8 and south | April; often self-seeds in mild climates |
Nasturtium is a frost-tender annual that's almost always direct-sown, since its roots are sensitive to transplant disturbance similar to dill's - but because it's so often grown specifically as a trap crop, timing it to be established before nearby vegetables are vulnerable to aphids matters as much as basic frost-safety.
Direct Sowing
Nasturtium seed is direct-sown once frost risk has passed, germinating quickly in warm soil - the large, easy-to-handle seed makes it one of the more forgiving flowers on this site to direct-sow, with reliable germination that doesn't demand the precision some finer seed requires.
Timing for the Trap-Crop Role
If nasturtium is being planted specifically as a trap crop for aphids around brassicas or cucurbits, sowing it at the same time as (or slightly before) the crop it's protecting gives it time to establish before aphid pressure typically builds - a nasturtium planted well after its intended companion is already established offers less protective value during the vulnerable early weeks.
Bushy and Climbing Types Share Identical Timing
Compact bushy nasturtium varieties and vigorous climbing types both follow the same direct-sow, post-frost planting window - the difference between them shows up entirely in mature growth habit and space needs, not in when either should go into the ground.
Self-Seeding Changes the Planting Decision in Later Years
In climates where nasturtium reliably self-seeds, the planting decision after the first year often shifts from active sowing to simply managing where volunteer seedlings come up - thinning or transplanting volunteers to the desired location rather than starting fresh from packet seed each spring.
Flowers and Leaves Are Both Edible
Both the flowers and the leaves are edible with a peppery, watercress-like bite, which is worth knowing if nasturtium is being grown as much for the kitchen as for its trap-crop role - harvest is simply picking blooms and young leaves by hand, with no special timing beyond avoiding any recently sprayed foliage.
Zone boundaries follow the USDA Plant Hardiness Zone Map (2023 revision); frost windows reflect NOAA/NCEI climate normals. Both are typical historical ranges, reviewed annually - not a forecast or a guarantee for any single year. See Methodology & Sources.
Frequently Asked Questions
My nasturtium plants have holes chewed all over the leaves - isn't it supposed to be the pest-magnet, not the pest's actual host?
Nasturtium works as an aphid trap crop specifically, but it isn't immune to every pest - cabbage white caterpillars and flea beetles will readily chew nasturtium foliage too, since the plant's peppery mustard-oil compounds that make it attractive to aphids don't repel every insect. Some leaf damage from a different pest doesn't mean the trap-crop strategy against aphids has failed; they're separate relationships.
If I deadhead spent nasturtium blooms to keep more flowers coming, will that stop it from self-seeding for next year?
Yes, largely - deadheading removes the developing seed pods along with the spent flower, so a heavily deadheaded plant produces meaningfully fewer volunteer seedlings the following spring than one left alone to set seed freely. It's a genuine tradeoff between maximizing this year's bloom and getting a self-sown planting next year, not something you can fully have both ways on the same plant.
Could planting a lot of nasturtium actually pull pollinators away from the vegetables that need them, instead of helping?
Nasturtium's flowers are genuinely attractive to pollinators, but this generally works in a vegetable garden's favor rather than against it, since drawing more overall pollinator traffic into the area tends to increase visits to nearby flowering vegetables too rather than diverting a fixed number of bees away from them. It's a different mechanism from the aphid-trapping role entirely - one is about drawing pests away, the other about drawing beneficial insects in.
Can I start nasturtium indoors if I want blooms earlier than direct sowing would give me?
Yes, though its roots are genuinely sensitive to disturbance similar to dill's, so starting it in biodegradable pots that go straight into the ground unbroken avoids the real transplant setback a bare-root move would otherwise cause to the young seedling.