Repotting your ZZ (Zamioculcas zamiifolia) is a suitable way to give it additional growing room and freshen the potting mix’s nutrients. Water is one of the necessary conditions that determine your ZZ plant’s survival after repotting. Thus, getting the water requirement right can be the difference between a thriving ZZ plant and one that struggles to survive.
You should water your ZZ plant after repotting it if it has outgrown its previous pot. However, you shouldn’t water your plant deeply right after repotting in cases of root rot. Instead, repot into lightly moist soil and wait until the top two inches (5 cm) are dry before watering.
In the rest of this article, I’ll discuss when you should water your repotted ZZ plant. I’ll also cover how to water the plant after repotting to prevent over or underwatering. Let’s get started!
Understanding ZZ Plants and Their Repotting Needs
ZZ plants are relatively low maintenance once they’ve been established. They also have low moisture requirements, able to thrive in moderately dry soil between waterings.
They grow slowly and live up to ten years when properly cared for. During their lifespan, it’s only natural to repot them a few times.
There are two main reasons gardeners repot their ZZ plants:
- When they’ve outgrown their containers
- When helping them recover from root rot
A ZZ plant’s repotting method and water requirements thereafter can vary depending on the reason.
Repotting an Overgrown or Rootbound Plant
A ZZ plant doesn’t like very large pots because they contain too much soil and hold too much moisture. This plant has fleshy roots and rhizomes that can rot when kept in very moist soil for a long time. It thrives best with a pot that’s about 2 inches (5 cm) wider than its diameter.
ZZ plants can grow up to 4 feet (1.2 m) tall and wide, but they can remain shorter and thinner indoors with proper pruning and timely division.
Also, if it’s too young to be divided, the best thing you can do when it becomes rootbound is to repot it. You’ll know that your plant is rootbound when the roots poke out of the soil and the soil dries out much faster than before. This usually happens when the plant has been in the same pot for two or more years.
Here are the steps for repotting an overgrown ZZ plant:
1. Prepare a Clean and Sterile Pot
ZZ plants will need a pot about 2 inches (5 cm) bigger than the current pot. Although they don’t like big pots, ZZ plants will benefit from heavy pots with good aeration and drainage. An unglazed terracotta pot with a drainage hole is ideal for ZZ plants. You can also use ceramic or plastic pots as long as they have good drainage and can support the weight of the stems.
It’s also important to clean the pots with soap and water and rinse thoroughly. You should also sterilize it using the steps below:
- Make a bleach solution containing a half cup (125 ml) of bleach in 4.5 cups (1125 ml) of water.
- Use gloves when handling the bleach solution.
- Soak a small pot in a basin of the solution or pour the liquid directly into the pot if you have a large one.
- Ensure that the solution touches all sides of the pot for thorough cleaning.
- Rinse and air-dry the pot.
2. Use a Fast-Draining Potting Mix
ZZ plants do very well in standard succulent or cactus mixes because they offer adequate drainage and aeration.
However, you can also make a homemade potting mix using one part perlite, one part sand, and one part compost. This combination will provide your plant with excellent drainage and adequate organic matter.
3. Water Your Plant 2-3 Days Before Repotting
Watering your plant a few days before repotting will help prevent transplant shock. It can also help loosen the soil more easily and have little resistance from the roots. Waiting a few days after watering will make it easier to take your plant out of the pot and remove the soil from the roots.
ZZ plants typically don’t need much water, but the soil of a rootbound plant dries out much faster. You’ll know when it’s time to repot your plant when the top 2 inches (5 cm) of the soil is dry.
If so, move your pot to a suitable working space, such as a garden shed, because the process can be messy.
4. Inspect and Prune the Roots as Needed
Carefully loosen the soil along the edges of the pot using a trowel. Hold the base of the plant firmly and tilt the pot to the side, almost upside down, and catch the plant as it slides out of the loose soil. You can also gently twist the pot and slowly pull it away.
Check the roots for any signs of decay. Healthy ZZ plant roots should be plump and white. Using a sterile knife or pruners, trim any darkened roots and remove a corresponding amount of shoots. For instance, removing 10% of the roots warrants the removal of 10% of the shoots.
You can use this opportunity to eliminate damaged leaves and stems. Removing as much foliage will help reduce the amount of aboveground parts the roots will support and also reduce the stress from transplant.
5. Repot the Plant in Fresh Soil
Place about 2 inches (5 cm) of soil into the bottom of the pot. Hold the plant above the soil, ensuring that the top of the roots is about an inch (2.5 cm) below the estimated soil surface, or 2 inches (5 cm) below the mouth of the pot.
Add fresh soil around the roots, keeping the plant in the middle of the pot. Give the soil gentle taps to keep it firm around the base of the plant.
6. Water Your Plant Deeply
This is the part where you must water the plant deeply right after repotting. Note that the potting mix of an overgrown or rootbound ZZ plant cannot hold enough moisture, causing it to dry out much faster. In that case, you’ll need to water the plant deeply after repotting to ensure it is well-hydrated.
Use filtered water or rainwater to feed your plant’s roots. Water your plant gradually until you see the excess drain out of the drainage holes. Let your pot sit on a drip tray until all excess moisture is drained.
Wait after the top 2-3 inches (5-7.6 cm) of the soil is dry before watering again. Check the soil moisture after 5-7 days to confirm if it’s dry enough. Otherwise, give it a few more days before watering again.
Repotting a ZZ Plant With Root Rot
Root rot is a common and often irreversible disease of plants that are constantly overwatered. Although many people label ZZ plants as hard to kill, these plants are also sensitive to root rot. Fortunately, you’ll have better chances of helping your plant recover if you diagnose the condition sooner. The only way is to repot the plant.
You’ll find that most of the steps for repotting a ZZ plant with root rot are similar to one that has outgrown its pot. But let’s discuss how they’re different.
Repot Immediately Regardless of the Season
You don’t have to wait until spring before repotting a ZZ plant suffering from root rot, especially when you start noticing the symptoms like mushy leaves and stalks and a distinctive decaying smell. Waiting until spring will most likely be too late for your plant.
Instead of waiting, you can repot the sick plant in any season. However, you’ll have to keep your plant indoors when repotting in the fall or winter for better chances of recovery. You’ll also have to keep the temperature above 50 °F (10 °C) at all times.
Use a Same-Sized, Sterile Pot
When repotting a ZZ plant suffering from root rot, you don’t need a larger pot. You’ll typically need to remove damaged roots but ensure not to remove more than 1/3. After securing and rinsing the healthier roots and rhizomes, you can repot the plant in a similar-sized pot.
In severe cases where more than a third of the roots are dark, mushy, and smelly, you’ll need to divide the plant and pick out the healthy rhizomes that you can replant.
In this case, you’ll even need to use a smaller pot, depending on how much ZZ plant you have left. Choose a pot that’s 2 inches (5 cm) wider than the plant’s base.
Drench the Fresh Soil With Subdue
Using the right kind of potting mix usually eliminates the risk of overwatering your ZZ plant again. I recommend using a cactus or succulent potting mix enriched with a gentle amount of nutrients to sustain your newly repotted plant until it’s ready for fertilizers.
Subdue is an effective fungicide that works against common causative agents of root rot, such as Pythium spp. and Phytophthora spp. You can mix 15 drops of Subdue Maxx with one gallon (3.8 liters) of water.
Soaking your new potting mix with this solution about one day before repotting your affected ZZ plant can help eliminate the fungi in the roots that weren’t removed through pruning. Follow the product label instructions carefully when handling this fungicide.
Prune the Decayed Roots
Always use sterile pruning shears when removing rotten roots. Spray the blade with isopropyl alcohol and wipe dry with a fresh cotton ball before hopping on to the next root or rhizome.
Remove brown, black, and mushy roots. If the stems are mushy at the base, remove them as well.
Using disposable gloves, you need to wash the roots with distilled or filtered water to remove the old, infected soil. Gently rub the soil off with your gloved fingers while flushing it away with water. Once you’re done rinsing, place the treated roots on a clean towel to dry a bit.
Meanwhile, place up to 2 inches (5 cm) of moist potting mix at the bottom of the pot. Position your ZZ plant into the pot and fill it in with moist soil.
Remember to keep the top of the roots about 2 inches (5 cm) below the top of the new pot. Cover the top of the roots with an inch (2.5 cm) of soil.
Don’t Water Immediately After Repotting
This is the most important difference when repotting a ZZ plant with root rot. The new potting mix should still be moist enough for the transplanted ZZ plant.
When repotting during the cold season, the roots won’t absorb much moisture so it’s best to avoid watering the soil immediately.
Wait until the top 2 inches (5 cm) of the soil are dry. The time it takes for the soil to dry out enough can vary depending on the temperature and humidity in your area. Manually checking the soil moisture before watering is crucial to avoid risking root rot again.
Alternatively, you can inspect the soil’s moisture content using a moisture meter to avoid over or underwatering the plant.
Here is a guide to using a moisture meter to get the correct moisture content reading:
- Insert the metal probe about ⅘ of the way into the potting mix. You must be careful to avoid hitting the plant’s roots or breaking the probe since it’s a brittle device.
- Give the moisture meter about 30 to 60 seconds to determine the moisture content.
- Note the reading and remove the metal probe from the soil.
- Wipe the probe and transfer it to the next location within the pot and take the new reading.
- Repeat the process until you’ve gone around the entire pot.
- Get the average of the results to determine the soil’s moisture content.
Based on the reading, you can determine if it’s time to water your ZZ plant or not. You can water your plant when the reader is in the dry range.
Here is a video that demonstrates this process:
Repotted ZZ Plant General Care Tips
Apart from water, a repotted ZZ plant needs nutrients and other provisions to thrive. Without these, your repotted ZZ plant is bound to fail.
Some general care tips for this plant include the following:
- Place the plant near a bright, indirect source of light. Although ZZ plants can tolerate low light conditions, they thrive in brighter, indirect sunlight. This is especially true when repotting your plant in the cold season due to root rot. The roots don’t have sufficient absorption ability, so the bright light will help the soil dry out faster.
- Maintain warm temperatures. ZZ plants thrive in temperatures between 60 and 75 °F (15.6 and 24 °C). Avoid exposing the plant to drafts or sudden temperature changes. This might cause leaf damage.
- Fertilize during spring and summer. These are the seasons when these plants are actively growing. Therefore, fertilizing them helps encourage healthy growth. However, don’t fertilize your plant immediately after repotting. Using the right potting mix should be enough to provide your plants with adequate nutrients.
- Be cautious when pruning ZZ plants, as they have a unique growing pattern. While you can cut off the yellow or brown leaves, you should leave the newly emerging ones, as they are integral to the plant’s growth.
- Watch out for signs of underwatering. ZZ plants can tolerate a bit of dry soil, but you might be so afraid of root rot that you end up underwatering your plant. When the leaves turn yellow and crisp, it’s a clear sign that your plant has been constantly underwatered.
Deciding whether to water your ZZ plant immediately after repotting depends on the reason why you had to move your plant to a different pot:
- Water your plant immediately after repotting due to being root bound.
- Wait until the soil is dry 2 inches (5 cm) deep when repotting due to root rot.
Keep in mind that using fast-draining soil is crucial every time you repot your ZZ plant to ensure it survives the transfer. Maintaining warm temperatures and keeping your plant in bright but indirect light are also necessary for optimum health.