You know how our long winter's cabin fever sometimes gets the best of our rational relationship with the sun. The first warm day of spring-like weather will appear and what do we do but shed our protective wool and goose down shells and run naked to the nearest beach or sand dune to flop down and take in some of that delicious, bone thawing warmth. Of course, within just minutes we're burned to a crisp, looking for shade and longing for a nice cool patch of aloe to sooth our red blistering skin and cracked, wind chapped lips.
It is at that moment we remember our most humbled relationship to the elements. We remember just how unprepared most of us are, coming out of our dark, protected winter caves into the harsh realities of the desert sun and wind.
After the skin damage is done, we remind ourselves of the importance of smooth transitions. And although people don't usually use the expression, the seasoned gardener would know what was meant if one were to say, "If only we had hardened-off."
Hardening-off is usually defined as an assisted process of adjustment conditioning for a plant that has been newly germinated or raised indoors or in some highly controlled space. The gardener helps the seedling or plant make the harsh transition between its initial, protected environment and the dynamic realities of its intended destination. Sometimes the plant's need for a gradual transition is due to temperature changes. At other times it's due to sun and light exposure. And often it's due to the differences between a windless, optimally controlled environment and its opposite: the erratic, unpredictable, highly inconsistent conditions of the outside world.
Hardening-off can also be defined in a broader sense. We can think of other types of transitions that plants undergo as examples of hardening-off. For example, xeric plants need help integrating into arid soil and full grown houseplants can be conditioned for seasonal environments that match certain growth and health requirements.
The process is accomplished by gradually exposing the plant to its intended environment. This way the plant gradually -- little by little, more and more -- becomes habituated to its future home. During the decreasing intervals between exposure the plant is kept within its former conditions as a way of protecting it from too much exposure in too short a time.
Start the hardening-off process a week to ten days before you plan to actually transplant the seedlings. Stay tuned to the weather station to make sure late frosts or cold snaps aren't predicted.
It's helpful to remember that the seedlings will be in small pots that can dry out much more quickly outdoors than indoors. You might want to begin the hardening-off process by placing the little pots on a porch or other protected space that gets only shade or filtered light of the morning sun. Make sure the space is protected from wind and the harshness of a mid-day exposure. Leave them in this simi-exposed place for a short while, no more than a few hours, then bring them back indoors. Do this everyday while gradually increasing their exposure. It's good to keep a close eye on them because you don't want to let them faint or dry out.
Each time you put the seedlings out, be sure to water them and if the weather report predicts excessive heat, you can place the pots in a tray with a 1/4 inch to 1/2 inch of water so the plants will be able to drink during the day. If it's crazy windy, you can bring them in and wait for another nice day.
After a week or so, your seedlings should be able to hold their own for most of the day. At this point it's time to let them camp outside for a night. Make sure the weather report isn't predicting any cold snaps. If you have more than one of a single type of plant (several eggplant seedlings, for example), you might want to hold some back in case that first night under the stars is too early. If all goes well, they can all camp out the next night. You might even want to camp out with them.
Soon your plants will be hardened up enough to be ready for a full life in the garden. Some gardeners hope for a mild cloudy day for the actual planting. Some even pray for light rain, but if the hardening-off ritual has been successful, planting in the morning with a good watering should be sufficient. If you notice fainting or stress, protect the seedlings with inverted pots or other types of shade relief.
Sometimes our customers will purchase drought tolerant plants from our nursery with the mistaken impression that since the plants are drought tolerant, they can simply be planted and then forgotten. The customers are surprised when only a few days later they go back to find the poor plant either stressed out, in shock or completely dried up and dead.
But, even drought tolerant plants that can take plenty of harsh conditions need what might be considered a type of hardening-off. But instead of helping the plant ease into cooler or warmer temperatures, or any of the other reasons plants typically need our assistance, xeric plants often need help establishing their proper water needs. To be sure, all plants need moisture. Some need a lot less than others, but those that need less need to be eased into a situation where they will able to find what they need on their own. Until then, they need our help.
The process of hardening-off xeric plants is the process of helping them establish their roots into a more or less drought-like environment. That is, they need to be periodically watered until their root system grows and integrates itself into the soil. Once the roots are able to find their own moisture, and according to the plant's particular needs and composure, hand watering can then taper off and become more sporadic and more desert like.
When you visit our nursery looking for drought resistant plants, talk to us, ask any questions you might have about xeric plants and the art of establishing beautiful and exciting low water landscapes.
Many houseplants actually love the warmth of our summer days and nights, especially different types of succulents, cacti and euphorbias. In fact, many such houseplants are intolerant of the low temperatures of our high desert winters rather than the intense heat of our summers. But even after the good temperatures have arrived, houseplants that do enjoy the heat often must get used to other factors, such as light and direct exposure to the sun. In fact, many houseplants that love a bright, sunny spot indoors actually prefer shade or filtered light in the outdoor garden. For example, the adored 'Christmas Cactus' loves to soak up sunlight while it sits indoors, but once outside, it will do much better in a spot that gets a limited dose of morning or afternoon sun.
Once you've discovered which of your houseplants enjoy the outdoor weather, and once the warmth has sufficiently arrived, you can begin bringing them out. For the first few days, you might want to bring them in during the evening, cover them or otherwise shelter them (on a covered porch, for example). For plants that will require shade, you might want to expose them for limited periods at first, especially during springtime, since the sun is less filtered while the tree leaves are still young and developing.
There are a variety of factors to anticipate. Often, gardeners will describe hardening-off in quite mystical terms, as a type of subtle intuition. But, if you do have houseplants that love our summer weather, easing them into outdoor exposure can promote good plant heath. The branches get needed exercise from the wind. The leaves get washed from water and rain. Pests like mealy bugs that might otherwise have free reign indoors get picked off and eaten by predator birds and insects.
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