If you garden with containers, there’ll come a time when you need to know how to repot a plant. As transplanting is stressful to the plant, it’s important to do it carefully and only when necessary. Knowing when and how to repot a plant will ensure it gains a new lease on life without coming to harm during the move.
Reasons to Repot a Plant
How do you know when it’s time to repot a plant? These are the most likely reasons for common container plants, whether grown indoors or out:
1. Repot a Plant to Give it More Growing Room
If a plant is still young and growing, it generally will need repotting every six months to a year to ensure its roots have space to develop. One sign of potential cramping is when new growth and leaf drop happen at the same time and at roughly equal rates. This shows that the plant can’t find enough resources to support the natural new growth it’s still creating, and repotting will ease the pressure.
2. Repot a Plant if the Roots are Growing Out from Under the Pot
However, if the roots start to emerge from the drainage holes at the bottom of the pot, the plant has likely already used up all its available space. It’s important to act quickly when this happens, to limit the root damage that repotting will cause.
3. Repot a Plant When the Potting Soil is Worn Out
Over time, the nutritional value and drainage quality of potting soil fade away. Feeding with fertilizer or topping up with a layer of compost will delay the inevitable, but eventually, a full replacement will be needed. On average, this will be every three or four years for mature plants.
4. Repot a Plant when the Container Wears Out or Gets Broken
Sometimes a pot might need replacing simply for practical reasons. Rotting wooden troughs, flaking or cracking terracotta, or corroded metal containers might all warrant a repot, even if the plant is thriving.
Pots can also get broken accidentally when plants get tipped by curious pets, toddlers, or the wind. In these cases, if the damage is severe, the plant roots should be covered with a plastic bag or placed in a temporary container to reduce stress and prevent the roots from drying out. Replace the pot and repot the plant as soon as possible.
Preparing to Repot a Plant
There are two important points to consider when preparing to repot a plant:
1. What Pot Size to Choose When Repotting Plants
If you’re changing pots to accommodate a growing plant, it’s important not to increase the size too quickly. Moving up by a standard pot size or an extra inch or two in diameter will give the plant more space without overwhelming it.
Plants growing in oversize pots can’t remove moisture from the soil quickly enough, and roots constantly sitting in wet compost are at risk of rotting. This is particularly important for houseplants, where overwatering is one of the most common causes of death.
2. Which Soil to Use When Repotting Plants
Unless the plant has a specific need, such as a coarse sandy soil for cacti or a particularly acidic one for blueberries, any well-balanced potting compost will be fine as a starting point. It helps to use a formulation specifically for flowers, vegetables, or herbs as appropriate, but the most important point is to always use fresh compost to avoid spreading infections.
5 Simple Steps for Repotting a Plant
1. Prepare Your Surface for Potting a Plant
Repotting can be a messy business, so cover your working area first. For smaller pots, a large tray will allow space while still catching spilled soil. For larger plants or shrubs, spreading a tarpaulin over a lawn or patio may be necessary. But whatever you’re repotting, you’re likely to need more space than you first think.
2. Filling the New Pot with Soil
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Next, take a sterilized container and cover the drainage holes with fabric, wire mesh, or shards of broken pot to keep them free of soil.
Fill the pot with potting soil to about a third of its height, compacting as you go.
3. Removing the Plant Root Ball from a Pot
Ease the plant out of its original pot and gently loosen the root ball while shaking off the excess earth. If the roots around the edges are particularly tangled and compacted, try to loosen them without tearing so that some are pointing outward.
4. Replanting into a New Pot
Place the plant in the new pot, ensuring that the top of the root ball is below the rim to allow for watering.
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Fill around the edges with compost, patting it down so that your fingers can’t easily push straight through, while keeping the plant as upright as possible. Make sure the top layer completely covers the root ball’s surface.
5. Watering Repotted Plants
Water well to settle the earth, topping up the compost if necessary, then water lightly or not at all for around a week to give the plant some recovery time.
Where’s the Gravel?
Traditionally, an inch or two of gravel has been added to the bottom of a pot to ensure good drainage. However, this stage isn’t really necessary.
If the roots need extra space, they’ll continue to grow into the gravel layer, where they’ll be deprived of nutrients and can even rot in any collected water.
If the drainage holes are kept properly clear with fabric, mesh, or shards, then any well-draining compost mixture should be enough to prevent waterlogging.
You can, of course, use a layer of pebbles or gravel to weigh down a pot for stability, but if so, consider using a slightly larger pot, so that root space isn’t reduced.
How to Combine Plants in a Pot
Mixed containers filled with a variety of blooming annuals, herbs, or foliage plants are the perfect way to create a garden “feel” in a small space. Basically, you will follow all of the same steps for repotting a single plant, but you will want to get a pot large enough to accommodate several plants.
1. Be sure that the plants you select for a mixed planting are compatible in terms of light and water needs. Fill the pot with soil leaving enough room to arrange the plants before filling it completely.
2. While the plants are still in their pots, you can experiment with different arrangements until you find a composition that you like. When repotting into a larger pot, it’s okay to place plants a little closer than you normally would if you were planting in the ground. Closer spacing will give your planter a lush look right from the start.
3. Keep the height of the plants in mind when arranging your plants in a pot. The tallest plant should either be centered or put towards the back of the pot if it will be near a wall or fence. Medium sized plants are next, and the smallest plants should be close to the rim of the pot. Trailing plants are a great choice for planting next to the edge of the pot where they can cascade over the sides, creating a dramatic effect.
4. Remove the individual plants from their pots, leaving them in their designated locations. Fill in around the plants with potting soil, straightening them as you go.
5. Water the container thoroughly to settle the soil around the roots. Add more soil if needed. Be sure to leave an inch or two of space between the top of the soil and the rim of the pot. This will create an area where water can pool until it drains down into the soil.
You can mix plants in a pot for indoor growing as well. For example, if you have a tree-type indoor plant, such as a ficus tree, you could grow a low or trailing plant around the base. Pothos and creeping fig are popular “groundcover” choices for planting around the base of potted trees indoors.
Once you’ve repotted your plants, why not show them off at their best? Read our article 5 Clever Ways to Use Plant Containers for ideas on where your displays can have the most impact.
