Spring: The Best Time for Transplanting

As the seasons change here in the northern hemisphere, plants are beginning to come out of the shock of the short, cold winter months. This is the transition time for all plants, inside or out. I have specialized in interior tropical plants for the past 37 years, but the same guides I use for inside plants also hold true for outside plants.
This transition is the time when plants are beginning to grow again. For interior plants, this is the absolute best time to transplant those over-grown specimens that have filled their pots with roots. The spring is best in the northern states because we are going into our tropical-like season with a prime environment for bringing plants out of the shock from disturbing their roots. The longer days and warmer temperatures are exact ally what these winter-stressed plants need to continue to flourish.

If you are one of those who just have to put all your houseplants outside (see "Putting houseplants out for the Summer".) you have probably watched them drop leaves during the short daylight hours in wintry to become a ghost of their lush selves, then this is the time you need to downsize the roots to match the smaller top growth. If your plants look bedraggled after the long dreary winter, now is the time to refurbish them. Most plants that have not been transplanted in several years, should be put into the next sized pot to give the roots more room to expand and help the plant to grow larger.

Pot sizes come in increments of 1 inch for the smaller sizes, and two inch increments for all pot sizes of 10 inches or larger. The pot is measured across the top rim; this gives the pot size. If your philodendron is in a 6 inch pot now, you can put it into a 7 inch pot if the old one is filled with roots. If there is any loose soil in the root ball, it is not time to transplant. Wait until the roots fill the pot in order to insure the plant is not over potted, which can lead to over watering.

Remove the root ball by turning the plant up side down and tapping the rim against the table, and gently remove the roots and dirt. If a little loose soil falls away you can still put the plant into the next-sized pot only. If the new pot has a drainage hole, place a flat stone or piece of broken pot over the hole, add enough soil to bring the top of the root ball to 1/2 inch below the top of the new pot. Gently fill around the root ball with good potting mix that is loose enough not to cake when watered, and water well. DO NOT FEED AT THIS TIME. Place the plant back into its location, and allow the surface to dry a touch before watering again. When you see signs of new growth, you can begin a low-dose of fertilizer mixed in the water weekly to promote stronger growth. Be careful with the fertilizer as most chemical and even organic fertilizer can burn delicate roots and cause severe leaf damage and even plant death if given at the wrong time. If you use a pot that does not drain (see 'Planting in Pots with no Drainage.) use a 1/2 to 1 inch layer of small stones on the bottom to create a water reservoir to protect the roots.

If your plant has lost 1/2 of more of the top foliage, you will need to do a root prune to bring back the balance between the top growth and the root system. This should only be done in the spring. Remove the root ball from the pot as above. Take a clean, sharp, non-serrated, long knife and cut the side of the root ball on all four sides. You can cut up to 1/2 of the roots at a time if the plant has lost over 1/2 its top growth during the winter. You can also just take a sliver off the roots, but you will have to prune again next year. Turn the root ball on its side and cut 1/3 to 1/2 off the bottom. Plant the down-sized root system into the appropriate size pot; it will be either the same pot or one that is smaller.

All plants grow according to mother nature's proportions. The top growth should always be 2/3 of the entire plant, and the roots should be 1/3 of the entire plant. Mother nature's 2/3 to 1/3 proportion is evident in all plant growth. When the proportion is off, the plant does not grow correctly and will always be off balance. It will not look right.

Again DO NOT FERTILIZE A NEWLY TRANSPLANTED OR ROOT PRUNED PLANT until new growth appears at the tips. Just water well and let the plant grow new feeding roots to replace those that were cut or torn when transplanted. Once you see new growth at the tips, the plant has come out of shock and you can begin a weekly fertilizing through the summer to give the plant the nutrients to grow strong, lush foliage.

Spring is also a good time to move those outdoor plants that are overgrown or just in the wrong place. I usually like to do this just as the new growth appears but is no taller than an inch or so. This allows me to take the correct plant, and I know it did not die in winter. When digging up the root ball, push the shovel deep into the soil several inches from the base of the plant. I usually suggest to move the plants on an overcast day so the foliage will not burn in the direct sun on the day of transplanting. Try to dig up as much soil and roots as you can and move the plant right away. If I am doing several clumps, I often cover the roots with a damp cloth to keep the roots from drying too much before they get planted again. I try to put in good compost and a bit of organic fertilizer in the soil I removed from the hole. Mix it in well. Put some in the bottom of the hole and then add the roots, keeping the stem above the soil line, and fill in with the mixture of old soil and additives. Water well. Again NEVER FERTILIZE these newly transplanted specimens for the first year in their new place. Perennials take a season to get established. Just keep watered for the first summer and let them adjust slowly. Then in spring of the following season, you can begin a strict regimen of weekly fertilizing all summer as soon as you see growth.

Trees, shrubs and perennials can also be moved or downsized in the fall after all the foliage has fallen. This is a good time to move them because they are in dormancy and the roots do not shock as deeply. This needs to be done before the ground freezes, and the roots should be mulched after planted. This helps the roots to winter over.

It is better to root prune and transplant houseplants in the spring, however, in the northern states because of the ideal conditions for the plant to come out of shock. In the spring, a plant will begin growing within 2 to 3 weeks after a root prune, and 8 to 10 weeks in the fall. In the south or west cost states, plants will come out of shock almost as well any time of the year.

So now that the good weather is upon us, at least in most places, refurbish those tired plants and help them grow large and lush in the coming season. Just remember to keep all your houseplants inside all year to help prevent the drastic environment change in the fall.