Gadenin日本語Get the appThe season in outline
Morning glory is an annual in almost every climate where it is grown from seed. The whole cycle runs inside one warm season: sow after the last frost, climb through early summer, flower from midsummer to frost, and die overnight when the first frost arrives. There is no overwintering and nothing to cut back and keep.
That compresses the useful decisions into a short window. Two of them matter far more than the rest: the seed treatment at sowing, and whether you improve the soil. Nick or soak the seed and you get an even stand a week after sowing. Leave the ground unimproved and you get flowers instead of a leaf factory. Everything after those two is maintenance.
Expect eight to twelve weeks from sowing to the first flower. Working backward from your own first frost date tells you the latest sowing that is still worth doing: if you have fewer than fourteen weeks of frost free weather left, the vine will only just be starting to flower when the season ends.
| Stage | What to do | What to watch for |
|---|---|---|
| Before the last frost | Put up supports; choose a lean sunny spot; do not improve the soil | Netting fixed firmly enough for a full grown screen |
| After the last frost, soil above 65F (18C) | Nick or soak the seed and direct sow half an inch (12 mm) deep | Even emergence in five to seven days |
| Two weeks after emergence | Thin to one plant per station, 6 to 12 inches (15 to 30 cm) apart | Weak seedlings shaded out by neighbors |
| Early summer | Start the vines by hand onto the support; spread them sideways | Shoots braiding together instead of covering the width |
| Midsummer | Water deeply; feed nothing, or half strength high potassium only | Lush leafy growth with no buds means stop feeding |
| Peak flowering | Count flowers weekly; remove reachable seed pods | Buds dropping after a dry spell |
| Late season | Leave a few marked pods to ripen if you want seed | Pods turning papery brown and splitting |
| First frost | Cut down and clear the vine; strip the netting | Fallen seed around the base, ready to self sow |
Early season: get the start right and the rest is easy
The support goes up before the seed goes in. Once a plant is in the ground, driving stakes cuts the taproot and threading netting behind a sprawling vine is miserable work. Fix the top of any screen to something solid, because a filled morning glory screen carries real weight and catches wind like a sail.
Sow only when the soil is genuinely warm, above 65F (18C). Treated seed sown into cold soil rots rather than germinating, and a sowing two weeks later into warm ground will overtake it anyway. There is no advantage in being early with this plant.
Thin without sentiment once the seedlings have two true leaves. Leaving three plants at a station gives three weak vines that shade each other at the base. Take the strongest, cut the others at soil level rather than pulling them, and the survivor keeps its roots intact.
- Guide the first two feet by hand Wind each shoot counterclockwise around the support every few days until it is two feet (60 cm) up. Once it has a firm grip on the netting it manages alone for the rest of the summer.
- Pinch the leaders once they reach the top This pushes side shoots that fill the bare middle of the support, where the flowers are actually at eye level. It is the most valuable ten minutes of the season.
- Set up watering before the heat arrives Mulch the base in the ground, and for containers plan on watering every morning in summer. A vine that dries out badly in midsummer drops its buds within a day or two.
End of season: seed, clearing up, and the self seeding question
Pods ripen from green to papery brown and split open to drop three to six hard black seeds. If you want seed for next year, mark one plant, leave a dozen pods on it, and collect them when the pod is brown and dry but before it splits. Store the seed dry, cool and labeled. It stays viable for several years, which is one consequence of that hard waterproof coat.
Everything else should come off before it ripens. Morning glory self seeds hard, the seed persists in the soil for two or three years, and seedlings keep appearing in beds long after you stopped growing it. In warm regions this is not a minor nuisance: morning glory is classed as an invasive weed in a number of places, where it smothers native vegetation and is difficult to remove from farmland once established. It is worth saying plainly rather than discovering it later.
If you garden in one of those regions, or you simply do not want the seedlings, the answer is straightforward. Remove the pods as they form rather than after they ripen, grow the plant in containers standing on a hard surface so fallen seed is easy to sweep up, clear the vine promptly after frost, and hoe the ground around the old support in spring. None of that is difficult, but all of it has to be deliberate.
Check whether morning glory is listed as an invasive or noxious species where you live before planting it in open ground. Where it is, grow it in containers and remove the pods before they ripen. Keep collected seed labeled and out of reach; it is toxic if eaten.
What a year of records gives you
Three dates and one weekly number are enough: the sowing date, the emergence date, the first flowering date, and a count of open flowers taken at a fixed time each week. Add a single line saying what you fed, even if the answer is nothing at all.
By the second season those notes answer the questions that otherwise go around in circles. How warm does my soil have to be before sowing works. How many weeks from sowing to the first flower in my garden. Which end of the screen flowers best. Whether that spring compost really did cost me the flowers.
Note the first frost date as well. It closes the year abruptly, and knowing your own average date tells you exactly how late a second sowing can go in before it stops being worth the seed.