Q– Chores: What should I be doing in the garden this month?
A– Rake up debris, and spread compost or aged manure on flower beds. Remove remaining dead plant parts. Wait to do any planting until the soil has dried out enough that a ball of soil will crumble in your hand. If you have a cold frame, put cool-weather-tolerant seedlings into it (gradually increase the time); or start cool-weather, early garden crops like peas, carrots, and greens by direct sowing in the soil of the cold frame.
Q–What plants can be planted outside now? (Central Maine)
A– Make sure the soil is dried out enough. Harden off any annuals before planting them. This advice applies to container plantings as well. After planting, cover them if a frost is expected. The following can be planted after April 15, if the soil is well-drained and temperatures are warmer (but we do not recommend planting that soon, and waiting until May 1 will give much better results):
Alyssum, Bacopa, Calendula, Dianthus, Diascia, Dusty Miller, English ivy, Lobelia, Calibrachoa, Nemesia, Osteospermum, Pansies, Petunias, Scaevola, Snapdragons, Sweet Peas, Vinca, Violas.
Q– How do I “harden off” plants?
A– Leave them in their original containers and put outside, out of direct sun and wind, for a couple of hours, then bring back inside. Increase the time they are left outside each day. Then plant in the ground after a few days. This decreases the transplanting shock, and the plants will be more likely to thrive. If you are putting seedlings started indoors into a cold frame, also use this gradual process. Row covers can help plants adjust during the earliest part of spring. When moving potted plants outdoors, like rosemary, increase their time slowly.
Q– What does “cover plants on frosty nights” mean?
A- If it seems especially cold at bedtime, or if the weather report forecasts widespread frost, the plants need a “blanket” to keep from getting damaged by cold. If you live in a cold area, such as the mountains or in a low spot (cold air sinks), even “scattered frost warnings” may apply to you. Appropriate coverings include row cover (Reemay), burlap, or old sheets. Heavier materials like actual blankets need to be kept off the young plants by stakes or some other system to prevent crushing them. Plastic is not as good a choice.
Q – What should I do to take care of bulbs that are coming up?
A– Remove leaves and debris that might interfere with growth. After green shoots appear, fertilize with a high-phosphorus fertilizer (P) and again around time of bloom. If possible, remove flower heads of daffodils and tulips so the plant’s energy will go into the health of the bulb, not into seed production. Do not cut back bulb’s leaves until they turn brown, and do not braid them (daffs).
Q– Do you have any tulip and crocus and daffodil bulbs for sale?
A– No. We sell those in fall, which is the best time to plant them. Bulbs growing in people’s gardens now were planted last fall, or a previous year. We do have some forced bulbs for sale in pots, though, until around Easter.
Q– Can I plant my forced bulbs in the garden, and will they come up next year?
A– Generally, yes. Fertilize the bulb plants while the leaves are still green with a product like Miracle-Gro. Wait until the ground thaws and is workable. By then, the flowers have gone by and the leaves have turned brown. Plant the bulbs in a rich, well-drained soil in full sun (partial sun is OK for daffs). Plant them deeper than they have been growing in the pot – 10” for tulips and 8” for large daffs and 5” for small daffs. Many tulip varieties do not return reliably from year to year, so gardeners often discard those. Daffodils may re-bloom for many years, if they are in a good location and if you fertilize them every spring.
Q– When can I divide my perennials?
A– Now is fine to divide most perennials, if the soil is “workable”. However, if a species blooms early, you may disturb this year’s flowering by dividing now, so it is better to wait till after flowering. Fall is the best time for moving or dividing peonies. Pay attention to how deep to plant them. German iris, for instance, must have the tops of tubers exposed in order to flower. Remember to make sure all new divisions and plantings are watered frequently until established.
Q– When can I plant perennials that I buy?
A– If you found them outside here at Longfellow’s, they are hardened off and can be planted out now. If they have broken dormancy (leafed out), cover them if you expect a frosty night, or they will get frost damage.
If you found them inside a greenhouse here at Longfellow’s, they have not been hardened off and must be exposed to the outdoors gradually. Even then, if leaves have developed, cover them on a frosty night.
Q– Why aren’t my perennials coming back? They died.
A– It is too early to know whether most perennials will come back successfully. Some stay dormant until quite late in the spring. Others may appear to have green on them now but will not have enough stored energy to make it through the rest of the spring. Wait to see what happens. If something really did not survive, it may be because of no mulch and inadequate snow cover, moles or other rodent damage, poor drainage, or a tender plant being planted in a too-harsh location. Other causes of winter death include having layers of flat leaves (like maple) packed down and smothering them, or loose mulch on the plants on top of a layer of snow, which also may smother them by causing the snow to pack into an ice layer.
Trees & Shrubs:
Q– What basic things should I know about planting trees & shrubs?
A– Make sure you have the right plant for the right location (eventual size, light requirements, soil drainage requirements, etc.). Remove the pot or burlap or other wrapping. If the roots are tightly grown among each other, loosen them up a bit. Dig a hole larger than the rootball. Amend the soil with a bag of compost. Plant at the same depth the plant was growing. Leave a bit of a depression around the rim of the hole to collect water, and do not mound up soil so water runs off. Water slowly and long, to make sure the planting hole is saturated. Water at least 1” weekly until the ground freezes in fall, and more often in very hot, dry weather.
Q– What should I do with the tree guards I placed around small trees last fall?
A– Remove them, so they do not restrict growth during growing months.
Q– Is this a good time to prune?
A– Once active growth is occurring, around mid-April to early June, pruning is not a good idea because sap is flowing so freely.
Q– My tree/shrub looks dead. Should I remove it?
A– It may just be late to leaf out. Some plants take longer than others. If it still shows no sign of life in late spring, you can assume it’s gone for good.
Q– What vegetables can be planted outside now? (Central Maine)
A– Make sure the soil is dried out and crumbles easily in your hand; otherwise, wait until it dries more. Harden off all transplanted seedlings, and wait until at least the middle of April for best results, unless you have a very protected area. From seedlings: plant lettuce, onions, some perennial herbs (including chives, parsley, oregano, thyme, sage, rosemary). Cover them if a frost is expected.
From seed: peas, turnips, beets, carrots, lettuce and other greens, onion sets, parsnips, radishes, broccoli & other members of the cabbage family.
Q– Why can’t I plant my tomatoes outside now? The snow is gone!
A– The soil is still cold, and night temps are much too cool for warm-weather crops like tomatoes, peppers, cucumbers, squash, beans, and basil. Even if they do not get frosted, they probably will succumb to disease. Wait until the end of May. Ways to speed things up: use raised beds, spread clear plastic on the soil to trap heat (black is second-best); use row covers, cloches, cold frames, Wall-of Water. Or plant in containers and bring in at night.
- Before doing any planting, make sure the soil has dried out enough that a fistful will crumble easily and not stick in a moist ball. Spring planting depends on warmth of the air, warmth of the soil, and having the soil dry enough to be workable without forming mud or clumps.
- Prune winter-damaged branches if you can tell they are clearly dead. Complete other pruning jobs in early April.
- Gradually introduce potted tender perennials, like Bay Laurel and Rosemary, to the outdoors, increasing their time a little each day.
- Remember to “harden off” all plants that have been growing indoors, before planting in the ground.
- Plant pansies and cool-weather vegetables in late April.
- On cold nights, cover new transplants.
- Fertilize spring bulbs.
- Divide summer-flowering perennials that are overgrown.