When Tomatoes Crack

A common annoyance for tomato growers is cracking, also called splitting or growth cracks. They appear suddenly on the fruit, usually just before harvest. Moreover, these cracks usually appear on several fruits at about the same time. And just when everything was going so well!

Why does this happen?

Well, it’s actually quite easy to understand.

Too Big for Their Skin

Cracking, which may be longitudinal (starting at the top of the fruit and descending part way down the side) or circular (around the peduncle at the top), is not a disease nor is it caused by any insect or other pest. It’s because the fruit starts to expand too quickly. Typically, this occurs when the plant suddenly receives heavy rain or a deep watering after a drought or at least a dry spell.

That means the fruit began to form in a situation where it was not getting enough water, so it remained a bit smaller than it would otherwise have been. Then, when water once again became abundant, the outer skin, not very elastic on many tomato varieties, failed to expand. However, the cells inside the fruit did expand as more water moved in and—presto!—the skin tore open, leaving a crack or several cracks.

Yes, You Can Eat Them

Don’t panic, though: you haven’t lost your crop! Split tomatoes are perfectly edible. Just cut off the wound if it bothers you. Of course, such tomatoes will no longer be marketable (if you sell vegetables), nor will they keep very long. They should be consumed or canned within a few days. If left too long on the plant, diseases can set in (including rot) and pests (earwigs, wasps, etc.) may visit or move in.

How to Prevent Cracking

The secret to avoiding cracked fruit is to learn how to water correctly.

• Water deeply and never let the plants dry out. The soil should be slightly moist at all times. If leaves start to wilt, you’re not watering thoroughly enough.
• Always water slowly, so the water can to sink down to the roots. Rapid watering, where only the soil near the surface receives its share of water, encourages cracking.
• Preferably, water without moistening the foliage. This has little to do with cracking per se, but helps prevent leaf diseases. Personally, I use a soaker hose, which ensures that the soil is well moistened while leaving the foliage totally dry, but other people prefer a drip irrigation system.
• A good, thick, organic mulch such as chopped leaves, up to 4 inches (10 cm) thick, makes a huge difference, since mulch reduces evaporation and keeps the soil cooler and more humid.
• Raised beds help too, as they allow excess water to drain away quickly when there is heavy rainfall.
• Plant more deeply in the spring, not just the root ball, but covering 4 inches (10 cm) or more of the plant’s stem. The lower roots, now deeper in the soil than usual, will be less exposed to drought and can help the plant find water during drier times.
• If drought-stressed plants are suddenly confronted with a massive rainfall (and that can happen!), it may be wise to harvest nearly ripe fruits without delay and to allow them to mature indoors in a dark pantry rather than let them overload on water and split on the vine.
• Growing tomatoes in tunnels or under glass helps prevent growth cracks because the fruits are protected from sudden downpours … and are usually watered with greater care!

Crack-resistant Varieties

Many varieties of tomato are naturally resistant to cracking, especially hybrid varieties, although crack resistance also occurs in heirloom types.

Sometimes you can easily replace a favorite variety prone to cracking with a similar but crack-resistant variety. For example, consider replacing the popular but crack-sensitive ‘Beefsteak’ and ‘Sweet 100’ tomatoes with nearly identical crack-resistant ‘Big Beef’ or ‘Sweet Million’ tomatoes.

Here’s a list of some tomato varieties with fairly elastic skin that are therefore more resistant to cracking. Of course, there are thousands of varieties of tomato and this list is far from complete. Ask your favorite seed supplier for suggestions of crack-resistant varieties!

1. ‘Ace 55’
2. ‘Arkansas Traveler’
3. ‘Big Beef’
4. ‘Big Boy’
5. ‘Black Cherry’
6. ‘Blondkopfchen’
7. ‘Box Car Willie’
8. ‘Bumble Bee’
9. ‘Burgess Crack Proof’
10. ‘Canabec Rouge’
11. ‘Celebrity’
12. ‘Chef’s Choice Orange’
13. ‘Chef’s Choice Pink’
14. ‘Chef’s Choice Yellow’
15. ‘Cherokee Purple’
16. ‘Chianti Rose’
17. ‘Colonial’
18. ‘Daybreak’
19. ‘Debarao’
20. ‘Delicious’
21. ‘Earl of Edgecombe’
22. ‘Early Girl’
23. ‘Eva Purple Ball’

    

24. ‘Fantastico’
25. ‘First Lady’
26. ‘Galina’
27. ‘Gardener’s Delight’
28. ‘Glamour’
29. ‘Gold Nugget’
30. ‘Golden Sweet’
31. ‘Grape Tomato’
32. ‘Green Tiger’
33. ‘Heinz 1350’
34. ‘Heinz 2274’
35. ‘Husky Gold Hybrid’
36. ‘Jackpot’
37. ‘Jelly Bean’
38. ‘Jet Star’
39. ‘Juliet’
40. ‘Ladybug’
41. ‘Marianna’s Peace ’
42. ‘Market Champion’
43. ‘Monte Carlo’
44. ‘Monte Verde’
45. ‘Morado’
46. ‘Mountain Delight’
47. ‘Mountain Fresh’
48. ‘Mountain Gold’
49. ‘Mountain Magic Cherry’

    

50. ‘Mountain Pride’
51. ‘Mountain Spring’
52. ‘Orange Zinger’
53. ‘Park’s Whopper Improved’
54. ‘Peron Sprayless’
55. ‘Petitbec’
56. ‘Piedmont’
57. ‘Pink Girl’’
58. ‘Pritchard’
59. ‘Prize of the Trials’
60. ‘Pruden’s Purple Tomato’
61. ‘Red Rose’
62. ‘Red Sun’
63. ‘Rosabec’
64. ‘Rutgers’
65. ‘Santa’
66. ‘Season Starter’
67. ‘Spitfire’
68. ‘Summer Sweet’
69. ‘Sun Sugar’
70. ‘Sunpride’

    

71. ‘Super Fantastic’
72. ‘Sweet Chelsea’
73. ‘Sweet Gold’
74. ‘Sweet Million’
75. ‘Sweet Olive’
76. ‘Sweet Orange’
77. ‘Sweet Treats’
78. ‘Sweethearts’ (‘Sweet Hearts’)
79. ‘Taxi’
80. ‘Terenzo’
81. ‘Thessoaloniki’
82. ‘Traveler 76’
83. ‘Trifele Black’
84. ‘Ultra Girl’
85. ‘Valentine’
86. ‘Valley Girl’
87. ‘Williamette’
88. ‘Yellow Pear’