Growing A Vegetable Garden

Whether you choose leafy greens, vine vegetables, or root crops, the harvest will be bountiful if you plant at the right time. Follow seed packet instructions for planting dates and the ideal growing conditions and ripening cycles of each crop.

July’s hot days can be tough on vegetables. Even when plants are watered in the morning, large-leaved crops like summer squash will be wilted in the hot afternoon sun. Does this mean an extra dose of water is needed? Not necessarily. Let the timing of leaf wilts be the guide in watering.

Large-leafed vegetables of the Cucurbitaceae family like cucumber, summer squash, and winter squash are 95% water. Cucurbits need a minimum of 1 inch of water per week to sustain their large leaves; water can be applied in frequent, small dribbles by drip or less frequently in larger quantities by furrow irrigations.

Consistent water application intervals is critical for proper plant and fruit growth and development; like the leaves, cucumber and squash fruit are mostly water. Consistent watering is critical for taste as cucumbers become bitter if stressed.

Knowing when to water is a maintenance gardening principle. There are two factors to consider – the above ground, plant side, and the below ground, soil side.

Plant side. Maintenance principle: the amount of water lost from a plant determines how much water needs to be replaced.

Water loss from a plant occurs by the process of transpiration, which occurs through miniscule holes in leaves. The larger the leaf, darker the color, higher ambient temperatures and lower relative humidity, the faster water exits from a leaf, resulting in increased transpiration and increased water loss.

Cucurbits with large, dark green leaves, such as summer squash, require a different watering regime than flowering plants like lavender with its small silver-gray leaflets. Therefore, a larger reservoir of available water is required to replace the water lost from summer squash, which leads us to the soil.

Soil side. Three soil water terms that need defining:

• Field capacity. A fully hydrated soil; holds the maximum amount of water against the force of gravity.
• Permanent wilting point. Water in soil is bound so tightly that it is unavailable to plant roots; plants will permanently wilt and not recover even with additional irrigations.
• Plant available water. The amount of water available for use by a plant for growth and development.

The gardener’s task is to determine the optimum time and amount to supply water to plants, keeping soil moisture between field capacity and the permanent wilting point.

Wilting does not mean there is insufficient water in the soil, rather, leaves have lost so much moisture that leaves are no longer turgid and they wilt.

Large green leaves, like those of Cucurbits, will almost always wilt on a hot, dry afternoon. With adequate available water in the soil, plants rehydrate over the cool night hours and leaves perk up in the morning.

Observe plants throughout the day. The signal to the gardener that there is insufficient available water is when plants wilt before noon or earlier. The soil needs more water that day, otherwise the plant will wilt – permanently.  

Ellen Peffley taught horticulture at the college level for 28 years, 25 of those at Texas Tech, during which time she developed two onion varieties. She is now the sole proprietor of From the Garden, a market garden farmette. You can email her at gardens@suddenlink.net

Source: lubbockonline.com