Gadenin日本語Get the appTendrils need something thin, and they need it close
A sweet pea climbs by tendrils: thin coiling threads at the end of each leaf that wrap around anything narrow enough to grip. The practical limit is about a quarter inch (6 mm), which is much thinner than the half inch a twining vine can manage. Netting, string, thin wire, twiggy hazel or pea sticks all work. A bamboo cane is already at the upper limit and a fence post is useless on its own.
Tendrils also have a very short reach. They will only grab what is within two or three inches (5 to 8 cm) of the shoot tip, which means a plant that gets more than a hand's width away from its support will never find its way back. Most of the sweet peas seen collapsed on a border are there because the support was put up a week too late or an inch too far away.
Height matters as much as material. Sweet peas run to six or eight feet (1.8 to 2.4 m) in a good season and will simply pile up in a tangled mass on top of anything shorter. A five foot (1.5 m) wigwam is full by early summer and everything after that flowers above the top, out of reach and out of sight. Build taller than feels necessary.
Whatever you build has to stand up to a summer storm when it is carrying a full curtain of wet foliage. That load is far greater than the bare structure suggests. Drive stakes a foot (30 cm) into the ground, brace wigwams properly at the top, and tie netting to a frame rather than hanging it loose.
| Support type | Height needed | Notes |
|---|---|---|
| Vertical strings or twine on a frame | 6 to 8 ft (1.8 to 2.4 m) | Cheapest and best for cut flowers; cut down with the plants at the end |
| Plastic or nylon netting, 4 inch (10 cm) mesh | 6 to 8 ft (1.8 to 2.4 m) | Even coverage; tie it taut to a frame or it sags under wet growth |
| Cane wigwam with string wound round | 7 ft (2.1 m) canes, 1 ft buried | Good in a border; the bare canes alone are too thick to grip |
| Twiggy hazel or pea sticks | 5 to 7 ft (1.5 to 2.1 m) | Looks natural and tendrils love it; needs replacing each year |
| Single cane per plant, cordon style | 8 ft (2.4 m) | For long straight stems; requires weekly tying and side shoot removal |
| Trellis with wide flat battens | Any | Battens are too thick for tendrils; staple netting or strings over it |
Get the support up before the plants go in
Build the whole structure before planting. Driving stakes beside an established sweet pea cuts the deep root that the plant spent all winter making, and threading netting behind a sprawling plant in early summer is miserable work that snaps stems. Plant at the base of a finished support, six to nine inches (15 to 23 cm) apart.
For the first two feet (60 cm), guide the plants by hand. Young sweet peas lean rather than climb and their tendrils will not reach a support they have fallen away from. Once a week, stand each shoot up against the netting or string and secure it loosely with soft twine or a plant ring, tying the string to the support and then round the stem in a figure of eight so the stem is not pinched.
Spread the shoots sideways as you tie. The natural tendency of a pinched plant with four basal shoots is for all four to follow the first one up a single strand, leaving the rest of the support bare and creating a dense knot that traps damp air. Send each shoot to its own part of the netting and the coverage fills in evenly.
After two feet the plant takes over. Tendrils grab everything within reach, including neighboring stems and their own flower stalks, and from that point on the only handling needed is untangling growth that has wandered off the support.
- Build to full height before planting Set the posts, canes or frame and fix netting or vertical strings from top to bottom. Bury stakes at least a foot (30 cm) and brace the top. A finished structure standing over bare soil is the target on planting day.
- Tie in weekly for the first two feet Use soft twine in a figure of eight, or plastic plant rings. Never pull the stem tight against a cane; sweet pea stems are hollow and crush easily, and a crushed stem wilts above the tie within days.
- Fan the shoots across the support Direct each basal shoot to its own vertical strand rather than letting them braid together. Even coverage means more light on more leaves, better air movement, and flowers at every height instead of one clump at the top.
- Check the ties again in midsummer Stems thicken through the season and a twine tie that was loose in spring can cut in by midsummer. Walk the row once, loosen anything tight, and re-tie any heavy growth that has pulled away from the netting.
Cordon growing, if you want long straight stems
Growing on the cordon is the method used for exhibition and for the longest cut stems. Each plant is reduced to a single stem tied to its own eight foot (2.4 m) cane, and every side shoot and every tendril is removed each week as it appears. Stripped of tendrils the plant cannot hold itself up, so the tying is not optional; it becomes a weekly task from spring until the end.
What you get in return is flower stems twelve to sixteen inches (30 to 40 cm) long, straight, with four or five well spaced flowers on each, instead of the eight inch (20 cm) stems with three flowers that a naturally grown plant produces. For cutting, the difference is obvious in a vase. For a garden display it is not worth the labor, because a cordon plant carries fewer flowers overall and looks stark on its cane.
When a cordon reaches the top of its cane, the traditional answer is layering: untie the plant, lay the bare lower stem along the ground, and re-tie the growing tip to a cane several places along the row. This buys another several feet of growing height without a taller structure. It is fiddly, and it is only worth doing if you are chasing stem length late in a long season.
Most gardeners should grow naturally: leave the tendrils on, let the plant find its own way up netting, and accept slightly shorter stems in exchange for far more flowers and almost no weekly work. Choose one method per row rather than mixing them, because a naturally grown neighbor will tangle its tendrils through a cordon and undo the whole point of it.
Note on your plan which support you used, how tall it was, and the date each row reached the top. If plants are consistently hitting the top of the structure by early summer, next year's support needs to be a foot or two taller rather than the plants needing anything different.
Wind, shade and where to put the structure
A full sweet pea screen behaves like a solid sail. Site it where it is not fully exposed to the prevailing wind if you have the choice, and if you do not, brace it far more heavily than looks necessary. A row that blows over in a summer gale takes the stems with it and rarely recovers, because the crushed and kinked stems wilt from the break upward.
Give the plants full sun for most of the day, but a little afternoon shade in a hot climate is a genuine advantage. Sweet peas are a cool weather plant and heat is what ends their season; a structure that catches some shade after mid afternoon flowers noticeably later into the summer than one baking against a south facing wall.
Leave room to walk both sides of the support if you can. Picking is the whole job with this plant and it has to be done every few days, so a row you can only reach from one side leaves half the flowers unpicked, and unpicked flowers set the pods that stop the plant.
Keep the base clear. Grass and weeds at the foot of the support compete for exactly the water the plants need most, and dense growth at soil level holds damp air against the lower stems, which is where mildew and rot start.