Wednesday, May 10, 2006
Growing Cacti - Shrinkage.
These Gymnocalycium plants are in different stages of progress between winter rest and going into their spring growth cycles. Many species of cacti noticeably shrink when they are in a state of dormancy and this is part of their ways of surviving through the coolest winter months. This winter dormancy is similar to that of deciduous trees losing their leaves for the winter, but with cacti they have shrinkage both above and below ground. This period lasts for about 4 months in nature and can even be as long as 6 months when cacti are kept as house plants. If the cacti in this photo are watered the one on the right will remain shrunken because it is still resting while the other two plants will benefit from and need water.
These cacti began to lose water in the fall, and it is normal for them to shrink and look smaller over the winter months. The squat appearance of the one on the right might remain the same even if it were given water, because it is still in a state of rest. The cactus on the upper left has entered its spring and summer growth cycle, and the plant just below it is only beginning to come out of its winter rest period. The two plants on the left need to be given plenty of water because they are in growth cycles, but the one on the right needs to have its soil kept mostly dry.
Watering can be a serious issue for these plants when they are in a shrunken condition, because their actual need for water depends on the specific season. In the summer months shrunken cactus plants may be suffering from dehydration, and actually need water to keep them healthy. However, in the winter months it is important to avoid assuming that a shrunken looking cactus needs water, because wet soil may do more harm than good. There are some varieties of cacti which will be at risk for rotting to death even if they are watered one time in their state of winter rest, like Copiapoa, Epithelantha, Eriosyce, Escobaria and Neoporteria species. In this situation a cactus may take one to two months before it finally dies, but the genesis of its demise will be from wet roots and fungus. Cactus plants can be at risk for fungal attack if their soil is wet when they are resting, and for most globular species it is best to keep them cool and on the dry side until spring.
With shrinkage it is important to understand whether cactus plants are in need of water or dryness, and basically spring and summer means water is needed and winter requires dryness. Cactus plants are much like deciduous trees in that they have a winter rest period where they need dry down time to get ready for their next growth cycle. In the spring cactus plants will start making new spines at the top of their stems and this marks the time when they are ready to be given plenty of water.
