Gadenin日本語Get the appWhy cucumbers are so thirsty
A cucumber fruit is more than ninety per cent water, and in the middle of the season a single plant is filling several ounces of fruit every day. All of that water comes up through the roots, so the demand is higher than for other fruiting vegetables, and because the roots spread through a shallow layer they feel every dry spell directly.
Half a day short of water is enough to leave the tip of the fruit unfilled, which is where thin, curved cucumbers come from. The compounds behind bitterness also build up when heat and drought run together. Flavor problems on a cucumber are far more often a water problem than a feeding one.
| What you see | The immediate cause | What to do |
|---|---|---|
| Wilts by day, recovers by evening | Transpiring faster than it can drink | Nothing is wrong. Increase the morning watering |
| Still wilted next morning | Root damage or root rot | Stop watering, let the soil dry, look for the cause |
| Fruit thin and curved | More than half a day short of water | Water more per application and add a mulch |
| Leaf margins scorching | Drought plus fertilizer concentration | Water deeply and skip one feed |
Judge wilting in the morning. Reacting to midday wilt by adding more water waterlogs the root zone and damages the roots you were trying to help.
How much water, and when
Water deeply rather than often. Repeatedly wetting only the surface keeps the roots up in the top inch of soil, and that plant is more vulnerable to drought, not less. Dig down four inches (10 cm): if it is damp there, you have watered enough.
| Stage | Frequency | Per plant |
|---|---|---|
| Just after planting | Every two or three days | About half a gallon (2 L) |
| Vine extending | Every one to two days | About three quarters of a gallon (3 L) |
| Peak picking | Every morning | About one gallon (4 to 5 L) |
| Heatwave | Morning and evening | One gallon in the morning, half in the evening |
Wilting during the day is not a problem if the plant is upright again by evening. Still wilted the next morning is the signal that the roots are in trouble.
The first picking is your cue to start feeding
Do not feed a cucumber at all between planting and the first fruit. Feeding early gives you a mass of vine and delays the female flowers. Once you have picked that first cucumber, start feeding and do not stop while the plant is producing.
- First feed on the day you first pick Carry the plant on the base fertilizer alone until you cut the first cucumber, then feed. Any earlier and you get vine instead of flowers.
- Then every ten to fourteen days Keep it up for as long as you are picking. A cucumber shows a missed feed in the shape of its fruit within a week, so fix a day and stick to it.
- Feed under the tip of the vine, not at the stem The roots reach out roughly as far as the vine has run. Fertilizer at the stem only reaches old roots, so scatter it along the shoulder of the bed.
Reading a hungry plant and an overfed one
A hungry cucumber makes smaller leaves first, then fruit that tapers at the blossom end. Once the growing tip is thin and the tendrils are short, it is already short of food. At that stage a liquid feed every few days will bring it back within about a week.
Overfed, it does the opposite: the leaves become unnaturally large and dark, the tendrils grow thick and long, and female flowers stop forming. The fix is to skip a feed, give water only, and let it set fruit again.
| Where to look | Underfed | Overfed |
|---|---|---|
| Tendrils | Short and thin | Thick and long |
| Leaves | Getting smaller | Unusually large and dark |
| Female flowers | Set, but the fruit tapers | Stop forming |
| What to do | Liquid feed every few days | Skip a feed, water only |
Leaves curling inwards with a dull, powdery look mean drought and overfeeding at the same time.
Mulch to protect the shallow roots
Because cucumber roots are shallow, they are fully exposed to soil that heats up in midsummer. Once the weather turns properly hot, lay straw or dried grass clippings about two inches (5 cm) thick over the bed and around the base. The soil runs cooler and you buy yourself slack in the watering.
A mulch also stops rain splashing soil onto the leaves, which delays downy mildew and anthracnose. If straw is hard to come by, dried lawn clippings, husks or fallen leaves all work.
- Mulch before the heat arrives Get it down before the soil heats through. Laying it late means you are chasing damage that has already happened.
- Two inches thick Thin mulch that lets the soil show through does nothing. Press it down until no soil is visible, and carry it out into the path to cut splashing.
- What you can use instead Dried grass clippings, rice or oat husks and fallen leaves all work. Do not pile on fresh green clippings, which heat up as they rot. Dry them first.
In containers, assume there is not enough root room
When a container cucumber suddenly stops producing in midsummer, the reason is almost always that there is not enough compost for the roots. Aim for one plant in a container at least a foot (30 cm) deep holding six gallons (25 L) or more. Below that, watering twice a day in hot weather becomes compulsory.
Every watering washes nutrients out of a container, so feed on a shorter cycle than in the ground, every seven to ten days, and keep the dose modest. Do not leave water standing in the saucer or the roots rot.
| Container size | Plants | Watering in high summer |
|---|---|---|
| Under 4 gallons (15 L) | One | Twice a day may still not be enough |
| About 6 gallons (25 L) | One | Once in the morning, twice in a heatwave |
| 12 gallons (50 L) and up | Two | Once in the morning is usually enough |
Screening the sides of the container with a board or a piece of hessian drops the compost temperature by several degrees and visibly reduces root damage in high summer.
Working out what went wrong
Curved fruit and a plant that suddenly stops come down to water, feeding or roots. Where on the plant the symptom shows tells you which of the three to fix.
| Symptom | Likely cause | What to do |
|---|---|---|
| Fruit tapers and curves | Short of water or food | Water morning and evening and add a light feed |
| Wilts by day, recovers by evening | Roots cannot keep up | Mulch to cool the soil and water more in the morning |
| Still wilted in the evening | The roots are damaged | Cut back the water, shade the plant, and pull it if it does not recover |
| Dark leafy growth and no fruit | Overfed | Stop feeding and pick everything off to lighten the plant |
The same wilt means different things depending on whether it recovers by morning. Watering a plant that has not recovered by evening damages the roots further.