Signs of spring are beginning to show here in the Pacific Northwest! Flowers emerging along with lengthening daylight hours finds us spending more time outdoors, but when seasonal showers chase us back inside, we can continue to garden by repotting our houseplants. Repotting indoor plants is best done during the active growing season—March through September.
Repotting doesn’t just mean changing containers—it means refreshing the potting soil. Soil contains the nutrients your plants need to thrive and just the right amount of oxygen and water for them to live, but eventually the nutrients get used up and the soil becomes compacted. You may even notice that your plants set lower in their pots than they did originally. Salts and minerals from synthetic fertilizers and tap water can also build up in the soil, resulting in burnt leaf tips or a white “crust” around the bottom or top edge of the container. This is why it is so important to repot your plants with brand new soil every year or so.
We are going to answer some initial repotting questions you may have and then we will walk you, step-by-step, through repotting your houseplants!
How do you know when it’s time to repot?
- Roots are growing through the bottom drainage holes
- Roots are pushing plant up and out of the container
- Plant is top-heavy and wants to fall over
- Soil dries out extremely quickly or has pulled away from the container sides and become hard
- Plant grows more slowly than usual
- Signs of salt/mineral build-up on top or bottom of the container
When is the best time to repot your plant?
Early spring, right at the start of the active growing season is often the best time for most plants. We suggest waiting about six weeks before repotting any new plant so it can adjust to its new environment without too many other change factors such as new container or different soil. Wait at least two days after watering so the soil holds together better when handling.
How often should I repot my indoor plants?
On average, mature plants should be repotted less frequently than young, faster-growing plants. Young plants may need to be repotted every 12 to 18 months, yet older plants that grow more slowly may be repotted every 2 to 3 years, or as needed.
How big should my container be?
It’s best to keep your new container no more than 2 to 3 inches larger in diameter than the one from which you are changing. Some plants may not need to have their container size increased, but still need their soil refreshed; in this case, you will want to remove about ⅓ to ½ of the old soil, loosen and lightly trim the roots, and add fresh soil to the bottom of the same or similar-sized container before replacing the plant in the pot and filling in the rest with fresh soil. Many types of popular indoor plants prefer to be in slightly small containers, especially those that are prone to overwatering or root rot (snake plants). However, some fast-growing plants can be planted in larger pots to accommodate and encourage rapid growth (monsteras).
Common Potting Soil Ingredients
Peat Moss/Sphagnum Moss: mined, organic material composed of partially decayed plant matter; improves air circulation and retains water; acidic in nature and contains less or no nutrients—if you’re using peat, you can add ¼ tablespoon lime per gallon in the mix to balance the pH. Although it is comprised only of organic material, it is not truly a renewable material as it takes thousands of years for wetlands to develop into peat reservoirs; see coco fiber/coconut coir below for alternative to peat moss.
Coco Fiber/Coconut Coir: trending potting soil ingredient made of shredded coconut skins, used to add bulk to potting soil mixes. It has the benefit of not being a mined product, and instead provides a use for something that may have been a waste product; it is a more sustainable alternative to peat moss and also a pH-neutral product. The downside of coconut coir as a potting soil ingredient is that it needs to be transported to northern areas where coconuts don’t grow. If you live far away from the production of coconut coir, you’ll have to weigh the sustainability of transporting coir to your area versus another alternative; check out what’s available in your area and decide what’s best for you—some people choose to mix peat and coir to get the benefits of both and balance out the drawbacks.
Compost: may come from many different sources such as decomposed vegetation, animal manure or other animal products, or wood fibers/bark; it can also be homemade.
Coarse sand: added for sharp drainage and to add weight.
Perlite: mined and heated volcanic rock that is added to soil mixes to help the soil hold air. Perlite holds 3 to 4 times its weight in water, increases pore space and drainage, and is pH neutral. Some of the perlite will float to the top of your plant container over time as it is much less dense than the other materials in the soil. Always wear a dust mask when mixing perlite or vermiculite into soil.
Vermiculite: mined mineral that has been heated; some gardeners prefer to use this rather than perlite—used similarly to perlite, vermiculite also contains calcium and magnesium, but it is generally darker in color, so it blends well with the soil and does not float to the top quite as much.
Pumice: volcanic rock that is heavier than perlite, but when added to soil, helps increase moisture and nutrient retention and improves aeration and drainage; ideal for cactus/succulent mixes to help anchor roots and provide stability.
Bark fines (shredded bark) or wood chips: finely shredded wood adds aeration and absorption, but also decomposes quickly and uses soil nitrogen in the process (pine uses less nitrogen). Chunkier bark provides aeration but is not very absorbent and doesn’t break down as quickly.
Lime: soil pH adjuster (increases pH)
Worm castings (Vermicompost): worm castings are basically composted worm poop; they are odorless and contain trace minerals and micronutrients beneficial to plant health.
Bat guano and kelp meal: organic nutrient sources
Charcoal: helps reduce odors and provides minor aeration
Custom soil mix for succulents & cacti: blend equal parts compost, coarse sand, fine (seedling) bark, and pumice; mix all ingredients together and pre-moisten before use.
Custom soil mix for aroids (Philodendron, Monstera, ZZ Plant): blend equal parts coco or peat-based potting soil (we like Baby Bu’s), fine (seedling) bark, and perlite; mix all ingredients together and pre-moisten before use.
Before Repotting, Gather the Following Materials
- Gloves, drop cloth, tarp, or newspapers to minimize mess
- Fresh indoor potting mix; we recommend Malibu Baby Bu’s Potting Soil, G&B Potting Soil, FoxFarm Ocean Forest Potting Soil, or appropriate soil for your plant; it’s helpful to pre-moisten soil before adding it to the container
- Slow-release fertilizer (we recommend G&B Organic All-Purpose, Joyful Dirt, or Osmocote)
- Small trowel or shovel for scooping soil
- Watering can and spray bottle
- Scissors or floral snips for light trimming of roots/leaves, and chopstick or other tool to gently untangle roots
- New container for plant*
*Make sure your new container has drainage holes! Without holes, water will sit stagnant at the bottom of your pot and cause root rot. If your container has no holes, plant into a plastic pot that can fit inside your decorative container; use Styrofoam or another material to prop up container so it sits near the top of the outside pot (not too deep inside).
Step-by-Step Repotting Instructions
NOTE: Thoroughly water your plant about 2 days before repotting.
- Turn your plant sideways, hold it gently by the stems or place your hand over the top of the soil, and tap/squeeze the bottom and sides of the container until the plant slides out. Use the base of the stems to gently tug if it doesn’t easily pop out.
- Once your plant is out of the container, use your fingers to loosen the roots and prune any dead stems, leaves, or damaged roots. If root-bound, unbind them as carefully and gently as possible.
- Remove about ⅓ of the old soil (discard or compost).
- Pour a layer of fresh, pre-moistened potting soil into planter, adding enough to keep plant at proper level.
- Add slow-release fertilizer and blend with soil (optional).
- Set your plant on top of the fresh soil; make sure it is centered and at proper height (top of new soil line is same as in original container).
- Add fresh soil around the plant’s roots and side of pot until it is nice and snug. Be sure to leave room; you don’t want the soil to go all the way up to the top of the pot; leave about a ½ inch before the top edge of the container so there is a place for water to sit before it is absorbed into the soil.
- Water your plant to settle the soil with enough water to drain out the bottom.
- Sit back and enjoy! AND be cautious when watering a newly repotted plant—if you have increased container size, you may not need to water as frequently as you did before repotting!