Cucumber, Muskmelon, and Watermelon

Introduction

Cucumbers and muskmelons (the genus Cucumis) and watermelons (the genus Citrullus) are related crops of tropical origin, and have similar cultural requirements. All three are tender, warm season vegetables that will not tolerate chilling or soil temperatures below 55°F. Having a good rotation plan is particularly important for these crops, as they are susceptible to several soilborne pathogens.

Types and Varieties

Cucumber types include pickling (short, with spines), slicing (long, with spines), and beit alpha types (long, with tender spineless skins). Cucumbers used for greenhouse or tunnel production should be parthenocarpic, meaning that they set fruit without pollination. Muskmelons have orange, musky flesh, and are the most common type of melon grown in New England. Specialty melons with white or green flesh include casaba, crenshaw and honeydew types. Watermelons exhibit a range of flesh colors (red, yellow, orange) and both seeded and seedless varieties are available.

CUCUMBER, MUSKMELON, AND WATERMELON VARIETIES  
Pickling Cucumber Slicing Cucumber
Alibi (50) - DM, CMV, PM, *S Intimidator (53) - A, Al, DM, CMV, PM, *S
Supremo (52) - A, Al, DM, CMV, PV, PM, *S Speedway (54) - A, Al, DM, CMV
Vlasstar (52) - A, Al, DM, CMV, *S Rockingham (57) - A, Al, DM, CMV, *S
Fancipak (53) - A, Al, DM, CMV, *S Dasher II (58) - A, Al, DM, CMV
Eureka (56) - A, Al, DM, CMV, PV, PM, *S General Lee (58) - A, Al, DM, CMV
Vertina (49) - CMV, PM, *S, P Marketmore 76 (58) - DM, CMV, PM, *S, OP
Excelsior (50) - CMV, PM, *S, P  
  Beit Alpha Cucumber
Muskmelon Katrina (49) - CMV, PM, *S, P
Goddess (70) - F012, PM Socrates (52) - PM, *S, P
Sarah's Choice (75) - F012, PM Diva (58) - CMV, PM, *S, P
Maverick  (78) - F02, PM  
Wrangler (80) - F012, PM Specialty Melon
Athena (82) - F012, PM, *S Diplomat (71)
Gold Star (87) - F012, PM Angel (60) - F02
  San Juan (78) - F012, PM
Watermelon - Seeded Sun Jewel (68)
Crimson Sweet (85)  - F, A, OP  
Sugar Baby (75) - OP Watermelon - Seedless
Sweet Favorite (80) - F, A Millionaire (90) - F, A
Crimson Delight (78) - F, A Gypsy (82)
Sangria (87) - F, A Solitaire (85)
  Orange Sunshine (85)

The number in parentheses is the approximate number of days to maturity from seeding.

Resistant or tolerant to: A: Anthracnose; AL: Angular Leaf Spot, DM: Downy Mildew, CMV: Cucumber Mosaic Virus, F: Fusarium (races indicated where known), PM: Powdery Mildew, PV: Potyviruses

Other codes: OP: open-pollinated, P: Parthenocarpic; *S: May be injured by sulfur sprays

Soil Fertility

Soils that warm up quickly in the spring are preferred over heavier soils that remain cool. Muskmelon should be grown on very well-drained soil for optimum quality. Raised beds provide additional benefits. The soil should be fertile and high in organic matter. On sandy soils, irrigation is necessary.

Apply lime according to soil test to maintain soil pH at 6.0 to 6.8. Watermelon can tolerate pH as low as 5.5. If the fertilizer cannot be banded at planting, add the band fertilizer amount to preplant broadcast application. If growing plants on plastic mulch, nitrogen can be applied through trickle or overhead irrigation or sidedressed along the edge of the plastic mulch. Nitrogen under the plastic mulch is protected from leaching. Foliar feeding rate is 8 to 10 lb actual N (4 to 5 lb urea) per acre.

If using transplants, use of a liquid starter fertilizer at planting time is beneficial, especially with cool soil conditions. Use a starter fertilizer mixed at a rate of 2 lb/50 gal water. Apply 8 fl oz (1 cup) per transplant.

Plant Nutrient Recommendation According to Soil Test Results for Cucumbers, Muskmelons, and Watermelons
CUCUMBERS, MUSKMELONS, AND WATERMELON NITROGEN (N)* LB PER ACRE PHOSPHORUS (P) LB P2O5 PER ACRE POTASSIUM (K) LB K2O PER ACRE
Soil Test Results   Very Low Low Optimum Above Optimum Very Low Low Optimum Above Optimum
Broadcast and Incorporate(Transplants) 50 110 60 0 0 150 90 0-40 0
Band-Place when Direct Seeding** 20-40 40 40 25-50 0 30 30 30 0
Sidedress When Vines Start to Run*** 40 0 0 0 0 0 0 0 0
TOTAL RECOMMENDED 110-130 150 100 25-50 0 180 120 30-70 0
*See Plant Nutrients for information on nutrient management and application.
**For direct-seeded cucumbers. For melon transplants, add the band fertilizer amount to pre-plant broadcast application. Total N and K2O in the band should not exceed 5.5 lb./1000' of row. Banded P2O5 may not be of benefit in warm soils.
***Sidedressing may not be necessary when using plastic mulch, or if organic matter can supply sufficient N; repeat sidedress in 2 to 3 weeks

Planting

Cucumbers may be direct seeded or transplanted. Because of the long season required for muskmelon and watermelon, transplants are used. Transplants are preferred for early crops. The plants should be about 3 weeks old, with just 1 to 2 true leaves, at transplanting time. Older transplants that have begun to run are difficult to handle and suffer greater transplant shock.

Recommended spacing for slicing cucumbers, muskmelons and watermelons is 2' between plants and 6' between rows. Pickling cucumbers should be direct seeded to 6" to 8" between plants and 3' to 6' between rows, depending on the cultivar. Most cultivars should be planted at 3' between rows.

Seedless watermelons require special growing conditions. Seedless cultivars are sterile because they are triploid, and this negatively affects their germination ability. They require high temperatures (85-95 degrees F) during germination, and excess soil moisture should be avoided. To ensure fruit set, a male polliniator variety must be planted among seedless watermelons in a ratio of at least 1 polleniator to 3 seedless plants.

In some growing seasons, vine crops that have recently been transplanted or have just germinated suddenly wilt and die. Most often, this situation occurs just following a period of 4 to 5 days of rainy or cloudy weather. Without sunshine, soil temperatures drop below 55°F to 60°F. At these soil temperatures the plant roots cannot absorb water from the soil. Consequently, when the sun does reappear, water transpires from the leaves much more rapidly than the roots absorb water, resulting in sudden wilting and death. There is no control for this problem, except to attempt to manipulate planting around weather forecasts. Earlier planting dates increase the likelihood of this problem.

Field Culture

Early and total yields are increased with black plastic mulch.  Before the plastic is laid, be sure the soil is fertilized and fitted to a smooth surface. The plastic should fit snugly against the surface. Do not lay plastic on dry soil; either irrigate or wait for rain to ensure the soil is moist prior to laying the mulch. In conjunction with plastic mulching, using hoops and spunbonded row covers will provide earlier and higher yields, while also helping to control insects such as striped cucumber beetle. Apply the covers at the time of planting and leave on until the time for pollination by bees (bloom). These crops can withstand high temperatures under the covers. A sufficient number of pollinating insects should be present to insure adequate fruit set in cucumber and melons. One strong hive of honeybees per acre as flowers just begin to open is recommended.

Harvest and Storage

Cucumber. Harvest on a regular basis to obtain a maximum number of fruits. Cucumbers are sensitive to chilling injury; optimum storage temperature is 50 to 55°F.  

Muskmelon. Unless they are to be shipped, harvest at full slip, when a slight twist of the melon will cause the stem to separate from the vine. Only well-netted muskmelons should be harvested; fruits with poor netting have generally been stunted in growth and lack good flavor. Hold muskmelons for 1 to 2 days at 70°F for final ripening; for longer periods of storage, maintain a temperature of 50°F to 55°F.

Watermelon. Varieties vary in maturity indicators. The proper time to harvest must be learned by experience (and perhaps by wasting a few fruits). Tendrils and ground spots are two generally reliable indicators of ripeness. When the tendril on the vine at the juncture of the fruit stem turns brown, the watermelon is close to maturity. A bright yellow ground spot on the underside of the fruit also indicates maturity. The thumping method to identify ripe melons can work, after some experience is developed. Store watermelons at 50°F to 55°F.