Frequently Asked Gardening Questions
At Plant Paradise Country Gardens™ it is our mission to provide the knowledge required to help you garden more successfully. These are some of the more frequently asked gardening questions that we have received. If you have a gardening qestion you would like answered please contact us. Visit our new blog at www.plantparadisecountrygardens.com for lots of gardening information.
How do I plant and care for Delphinium elatums?
Dig about eighteen inches deep and three feet wide and mix composted manure or worm castings into your soil. They are heavy feeders and require a spring feeding of composted manure or worm castings every spring. To produce tall bloom spikes, it is recommended you sprinkle some all purpose Gaia Green organic fertilizer (4-4-4) along with some Glacial Rock Dust every three weeks until they bloom.
Plant them in full sun for optimum growth. Gently tease the roots loose if they are tightly wound. When planting do not cover the crown of the plant. If you do, it will rot. Sprinkle some micorrhizal fungi (MYKE) at the bottom of the hole. The addition of MYKE fungal innoculants will get your plant established quickly. Place the delphinium in the hole with the roots touching the micorrhizal fungi, then water the roots and allow the water to filter into the soil before completely backfilling to the existing soil level. Water again. When placing the delphinium in your garden, allow a three foot diameter for future growth. They need good air circulation to prevent issues of mildew and fungal disease from occurring.
They need to be staked to prevent the tall bloom spikes from breaking. We have found the best plant support system is a grid system with two powder coated steel stakes. The circular grid holds each bloom individually. This plant support system should be placed around the middle of May to allow the plant to grow through the grid. As it grows up through the grid, gently slide the grid up the two stakes.
After blooming, cut back the bloom stems right to the ground and dispose of all old foliage. Delphinium stems are hollow and this method does not allow any water to accumulate in the stem and potentially rot the crown. Do not cut off any new foliage that is close to the ground. This is the growth to encourage re-bloom in the fall. This is a good time to sprinkle some more all purpose Gaia Green organic fertilizer and water it in. Do not cover or protect them in the winter, as the snow insulates them. It takes about two years for delphiniums to become fully established. If you wish to divide them, it may be done after five years. It is best done in early spring when the plant is approx. three inches high. If you have a problem with slugs, Safers Slug and Snail bait works well. Also removing all foliage in the fall helps to control any slugs from wintering over. Powdery mildew can be problem in a dry garden so keep your delphiniums well watered when they are growing. Perennials need one inch of water per week.
How and when do I prune my clematis?
There are four different clematis pruning methods, depending on the variety of clematis that you grow. If you do not know the variety’s pruning method, you must get to know how your plant grows and blooms and then prune accordingly. No matter which variety you grow, pruning is always done in the spring. The following are clematis pruning guidelines only. Group 1
- These flower in early spring entirely on last season’s growth. Therefore no pruning is done until right after flowering. All that is required is to remove weak or dead stems.
- They flower in early spring to early summer on previous season’s growth, then they bloom again on new growth later in the season. Prune lightly in early spring to vary the stem length, but not enough to remove the bloom buds set the previous year. (Probably only a short piece of stem is required.)
- Flowers on both last year’s and new year’s growth at the same time, generally mid to late summer. Prune lightly in the spring to remove dead or weak wood.
- Flowers only on the current season’s growth. New growth starts each year where the previous growth finished. Unpruned vines will get large and out of control and bloom only at the top. To control, cut back in early spring to two sets of buds, as close to the ground as possible.
When should I cut back my perennials?
Perennials can be cut back in late fall, as you see the dead or dying foliage. This occurs usually in October or November when the weather starts getting cold, depending on where you live. Keeping the garden free of decomposing debris helps control insects and disease that might overwinter in the decaying vegetation. This includes getting caught up on any weeding that requires attention. Sunny gardens benefit from having a complete clean up because the crowns of these perennials don’t tolerate being covered by moist, decaying vegetation. Not all gardens require removal of finished vegetation for the winter. Woodland or shade gardens usually have plants that benefit from a covering of decomposing vegetation. Imitate nature by applying shredded leaves that you have collected. Shred the (dry) leaves you have collected by running a lawn mower over them a few times. Apply a layer of two inches around your perennials for a nutrient rich leaf mulch which contributes to fertility and moisture retention. Some flowering woody shrubs and perennials regrow from stems that have wintered over under the protection of snow. Butterfly bush, Russian sage, lavender. euphorbia, artemisia and certain varieties of hydrangea are best left until late May or early June for a light pruning. Evergreen plants such as candytuft, moss phlox, and dianthus should not be pruned in the fall. Leave these for spring pruning. Ornamental grasses are cut back right to the ground in early spring.
How do I get rid of slugs?
To get your slug situation under control with respect to the environment and the safety of pets and children it is best to use a product that contains iron phosphate. Iron phosphate usually occurs naturally in the soil. Safer’s Slug and Snail Bait contains iron phosphate.
Should I divide my perennials?
Over time perennials do require dividing. The signs to look for may include:
- The center of the perennial has died, leaving a dried up empty hole.
- If the perennial is overgrown, the flowering may have declined.
- If a large clump has exhausted the nutrients in the soil it may show signs of yellow leaves, stunted growth or very few blooms. This would be the time to divide and replenish the soil with composted manure and also add an organic fertilizer.
When is the right time to divide perennials?
Spring is usually the best time to divide perennials (April/May), but it can also be done in early fall (September). Generally, divide plants that bloom from mid to late summer in the spring, and early season bloomers in the fall. Some spring bloomers are best divided shortly after they flower. These include phlox subulata, aurinia, rock cress, bearded iris and primrose. Dividing perennials in the spring gives you an entire season of growth and creates stronger plants before the winter arrives. When you have plants with well established roots, there is less chance of the frost heaving them. This is where the frost will heave newly planted perennials right out of the ground. This is also why dividing perennials should not be done after September. Perennials require at least six weeks of growth before the ground freezes. However, some plants survive better if division is done later when they are dormant. These include peonies (September/October) and oriental poppies (August). Daylilies can be divided anytime during the growing season, but I like to divide them in the spring. Ornamental grasses are divided in the spring.
How do I divide my perennials?
- If you are dividing in the spring, wait until your plant shows signs of growth in the spring, about an inch or two of new growth. If you are dividing in the fall any growth should be cut off by one half. Gloves should always be worn when dividing perennials, as some plants may irritate your skin.
- Dig up the entire clump from about three to four inches outside where the growth appears. Dig around the entire plant and under it before lifting it out. Knock off any loose soil by hitting it against your shovel. Sometimes I use my garden hose to spray off (high pressure) excess soil from the roots. I then use a large rubbermaid container to place the freshly dug plant in. I use the container to transport the plant to my work bench.
- Use a sharp knife. I use my Hori Hori knife and cut down the center. Depending on the size of the clump you can make a few more divisions, but I try and keep the portions large enough to still remain a good size plant.
- Some plants require only hand division after being dug up. This involves gently separating the individual roots or rosettes.
There are a few examples below of both spade division and hand division.
Dig up and divide these plants with a spade
Dig up and divide these plants by hand
How do I plant my peonies?
Peony roots have eyes, which should be red/pink and firm. Position the root so that these eyes are no more than 1 1/2 to 2 inches deep when planted. When planted too low, peonies will produce lots of leaves and very few blooms. Feed peonies only once a season with an organic fertilizer, as over fertilization will result in fewer blooms. Some of the most common reasons the peony doesn’t get many buds is that they may be too young, planted too deep, over-fertilized or not receiving enough direct sunlight. An older plant may begin to bloom less. This maybe a sign that it is time to be divided and replanted.
My mophead hydrangeas have lots of beautiful green growth, but no bloom. Why not?
To start off with, the Mophead hydrangeas are known as the “macrophylla” variety of hydrangea. These varieties should not be pruned in the spring. They set next year’s bloom buds in the fall. Another reason that your mophead is not blooming is that in colder growing regions such as Zone 5 or 4, these hydrangeas require enough warm days in the fall to allow the bloom buds to mature enough to withstand the cold winter. This usually does not happen and the bloom buds will turn black. The “Endless Summer” variety of hydrangea macrophylla is the exception because it is hardy to Zone 4 and blooms on old and new wood.
The best and most reliably hardy hydrangea varieties to grow in a Zone 4 or 5 area include the paniculata varieties such as “Pinky Winky”, “Limelight”, “Phantom”, “Quick Fire” and The “Swan”. Also the hydrangea arborescens varieties are even hardier (Zone 3): such as “Annabelle” and the newest varieties “Incrediball and “Invincibelle Spirit”.
When do I prune my hydrangea?
This depends on the variety you are growing. The Hydrangea paniculata varieties require a light pruning in the spring, however it is not necessary to prune them every year. The Hydrangea arborescens varieties require pruning of last year’s growth in early spring (before the new growth appears) or in late fall. It is important to know that the Hydrangea macrophylla (or mophead varieties) do not ever require pruning unless there is dead wood or they are very old. If required, the Hydrangea macrophylla varieties should be pruned before August. Pruning after July will result in fewer blooms the following summer. With the exception of the Hydrangea macrophylla “Endless Summer” variety which will bloom no matter if you prune it in the spring or the fall.
How do I get my wisteria to bloom?
Stop feeding it nutrients with high amounts of nitrogen. Fertilizers with high amounts of nitrogen will contribute to lots of green growth, but very little or no flowers. Root pruning will help, but it is best to prune a wisteria’s new growth shoots. From the old woody main stem there will be green new growth. On this new green tendril, count five to six new leaf nods out from the old woody stem and prune at this point. If you need to prune a wisteria that does bloom, prune right after it blooms in this same method. Please contact us if you have any gardening questions.