How to Plant Zucchini: Spacing, Soil Warmth and How Much Room It Needs

It does not vine, but it takes a lot of room

Zucchini is a squash, but instead of running along the ground it throws leaf stalks up from the crown in a rosette. It does not take over the bed the way a trailing squash does, but the leaf spread passes three feet (1 m) across, and by late season neighboring plants overlap.

Allow roughly a square yard per plant. Crowd them and the leaves overlap, the crown stays humid, powdery mildew arrives earlier, and the female flowers hide under the leaves so you are pushing foliage aside every time you pollinate or pick.

1. Think about which way it leans The leaf stalks fall towards the light. If they fall into the path you snap them every time you walk past, so plant so they lean into the bed.
2. Think about what is next to it A tall crop on the sunny side makes the stalks stretch. Put zucchini on the shaded side of the plot rather than under something.

Plant once the soil is above 54F

Judge planting by soil temperature rather than by the calendar. Below about 54F (12C) at night the roots do not move, the plant is slow to establish, and it goes into flowering small. It grows best between 68 and 82F (20 to 28C), and it takes off once days are settled around 77F (25C).

1. Planting early If late frost is still possible, put a cloche or row cover collar over each plant for a fortnight. It also stops the wind snapping the leaf stalks, and the plants establish noticeably faster.
2. Planting late Planted well after the last frost, early growth is fast and the plant is ready quickly. The trade-off is that picking then coincides with the worst of the powdery mildew, so the season is shorter.

Three feet each way, one row

A bed three feet (90 cm) wide, plants three feet apart, in a single row. Closer than two and a half feet does not increase the crop, it just speeds up the spread of disease. Build the bed six inches (15 cm) high, and higher on badly drained ground.

1. One row, not two A double row closes the middle of the bed and you cannot get a hand in to pollinate or pick. Even on a wide bed, plant a single row and use the rest as path.
2. Leave two feet of path The stalks reach outwards, so a narrow path means snapping them every time you pass. A snapped stalk is lost photosynthesis and the next fruit fills more slowly.
3. Use black mulch It warms the soil and stops rain splashing disease up from the ground. Silver mulch also reduces aphid arrivals, which is your early virus control.

Keep the base dressing light and feed as it crops

Too much base fertilizer gives you a forest of leaf stalks and the female flowers stop. Zucchini crops for two months, so keep the base dressing to a normal rate and carry it with feeds once the fruit starts.

Aim for a pH of 6.0 to 6.5. Do not apply lime and compost on the same day: leave a gap between them.

Plant at three or four true leaves

A zucchini plant grows fast and does not transplant well once it is large. Three or four true leaves with the seed leaves still attached is the point to plant.

1. Choosing a plant Three or four true leaves, short leaf stalks, seed leaves still there. A stretched plant with long stalks flops after planting and the roots lift.
2. Making the hole Fill the hole with water and let it drain before setting the plant. Set the rootball level with the surface, never deep, or the crown sits wet and rots.
3. The first week Do not let it dry until it has taken. Water at the base in the morning. One hard wilt now delays the first female flower by several nodes.
4. Add a short stake Push a short cane in and tie the plant loosely. Wind rocking the crown breaks the fine roots and costs a week of establishment.

Grafted zucchini plants are rarely sold, so most are on their own roots. On ground that has grown squash before, moving the crop is more reliable than anything else.

Growing in a container

The roots are shallow and wide, so what matters is volume rather than depth. Under six gallons (25 L) the plant wilts even watered twice a day in high summer and the fruit stops partway. One plant per pot, at least sixteen inches (40 cm) across.

Stand containers on bricks rather than directly on the ground. The compost runs cooler and the drainage stays clear.