Gadenin日本語Get the appWhy a pumpkin will climb at all
Pumpkins produce tendrils at almost every node and will grip anything within reach, which is why runners left on the ground still climb into a nearby hedge. The tendrils are strong enough to hold the vine but nowhere near strong enough to hold the fruit, and that single fact is the whole of vertical pumpkin growing.
Grown up a support, one plant occupies perhaps ten square feet (1 sq m) of ground rather than forty. The leaves get light and air from both sides, mildew arrives later, fruit never touch wet soil and you can see every flower without kneeling. The cost is building something strong enough and slinging every fruit.
- Match the fruit size to the method Fruit up to about eight pounds (3.5 kg) are straightforward on a trellis. Between eight and fifteen pounds (3.5 to 7 kg) needs a well-made sling on a solid frame. Above that, grow it on the ground.
- Expect to tie in weekly Tendrils alone will not hold a loaded vine. Plan on a few minutes each week tying the leader in as it climbs, right through the season.
Building something that will actually hold it
A mature vine carrying three fruit and a canopy of wet leaves in a summer gale puts a serious load on its support. Trellises fail in exactly that combination of conditions, and a collapse at that point loses the whole crop. Overbuild it.
| Component | Specification | Reason |
|---|---|---|
| Uprights | 2 by 2 in (5 by 5 cm) timber or steel posts | Canes bend under a loaded vine |
| Post depth | 18 to 24 in (45 to 60 cm) into firm ground | Wind loading on wet leaves is the failure mode |
| Height | 6 to 7 ft (1.8 to 2.1 m) | Anything you cannot reach you cannot pick |
| Mesh | Steel mesh or heavy netting, 4 to 6 in (10 to 15 cm) squares | Small mesh leaves nowhere to pass a sling |
| Angle | Upright, or leaning 15 to 20 degrees | A slight lean makes fruit hang clear of the frame |
| Bracing | Diagonal brace at each end | Stops the frame racking sideways |
Build it before you plant, not after. Driving posts through an established root system does real damage, and a vine that has already sprawled cannot be lifted onto a frame without breaking runners.
Training the vine up
The routine is simple and it is weekly. Guide the leader upward, tie it loosely to the frame, and let the side shoots fan out to fill the mesh. What you are avoiding is a vine that grows two feet sideways while your back is turned and has to be bent back into place when it is already stiff.
- Start it early Begin tying in as soon as the plant starts to run. A young runner is easy to place. One left loose for two weeks has already committed to a direction.
- Tie loosely in a figure of eight Use soft ties, twisted between the stem and the frame so nothing rubs. The stem thickens through the season, so leave slack and check the old ties monthly.
- Tie in every eighteen inches A tie every foot and a half (45 cm) of stem. Fewer than that and the weight hangs on the tendrils, which tear away in the first strong wind.
- Fan the side shoots Spread laterals sideways rather than letting them pile up. Even leaf spread across the mesh is what gives you the light and airflow you built the frame for.
- Stop it at the top When the leader reaches the top bar, pinch it out. Letting it trail over and down shades the frame from above and blocks airflow through the whole plant.
Slings: the part that cannot be skipped
The stem attaching a pumpkin to its vine will not hold a ripening fruit. It tears out somewhere around two to three pounds (1 kg), usually overnight, usually within weeks of harvest. Every fruit on a vertical vine needs its own sling, and it needs to go on early.
The sling carries the weight, not the frame member above it, so tie the sling to a structural part of the trellis. Tying it to the vine itself simply moves the tearing point along.
- Sling at the size of an orange Fit the sling well before the fruit is heavy, around three to four inches (8 to 10 cm) across. Retrofitting one to a heavy fruit is how stems get broken.
- Use breathable material Old netting, mesh produce bags, cut-up stockings or strips of shade cloth. Solid plastic traps moisture against the rind and the fruit rots where it sits.
- Cradle the base, not the shoulders The sling should hold the bottom of the fruit like a hammock. Anything that grips the sides scores the rind as the fruit expands, and that scar becomes a soft spot in store.
- Leave room to grow Fit the sling with plenty of slack. A pumpkin can double in a fortnight, so check every sling weekly and let it out before it starts to bite.
- Tie above, to the frame Attach the sling to a horizontal frame member directly above the fruit, so the load runs into the structure and the fruit stem carries nothing.
What changes when the plant is off the ground
Vertical plants dry out faster, because a smaller root run has to supply the same amount of leaf and there is more air moving through the canopy. Watering and feeding both need to step up, and if the plant is against a wall the difference is greater still.
| Aspect | On the ground | On a trellis |
|---|---|---|
| Ground used per plant | About 40 sq ft (4 sq m) | About 10 sq ft (1 sq m) |
| Watering | Deep, once or twice a week | More often, the root run dries faster |
| Feeding | Every three weeks | Every two weeks, no root spread to draw on |
| Powdery mildew | Common by late summer | Later, air moves on both leaf surfaces |
| Fruit rot underneath | A regular problem | Effectively eliminated |
| Practical fruit size | Any size | Up to about 15 lb (7 kg) |
A trellis against a south-facing wall gets hot and dry. Pull the frame six inches (15 cm) clear of the wall so air can move behind it, and mulch the base heavily.
Harvest and what to record
Cutting a slung fruit is a two-handed job, and it is worth thinking through before you are standing there with loppers in one hand and a ripe pumpkin in the other.
- Support before you cut Take the weight of the fruit in one arm, or have someone else hold it, and cut the vine above the stem afterwards. Cut first and it drops into the sling and bruises.
- Keep the long stem The same rule applies as on the ground: three to four inches (8 to 10 cm) of stem, never carried by the stem. Storage life depends on it.
- Note the fruit weight against the sling Record what each fruit weighed and whether its sling held comfortably. That number tells you what your frame can carry next year better than any general figure.
- Record where the vine reached Note the date the leader hit the top of the frame. If it arrived in midsummer, build higher or start the plant lower next season.