Adrian Higgins gave advice on spring gardening

Mar 28, 2013

Washington Post gardening columnist Adrian Higgins takes questions on how to get your garden going at springtime.

Mr. Higgins: I have a substantial container garden on my deck with very large pots that I plant every year usually with spectacular results. My question is do I have to remove and replace all of the soil in the pots? Yearly it has become a daunting, back breaking task to prepare for planting, to say nothing of where I am to dispose of the old soil. I am using a mixture of soil, peat, and perlite Please advise. Many thanks.

My instinct is to say, yes. You should, because plants in containers extract all the goodness from a limited soil mass. You also have soil compaction and the risk of disease build up. You could remove half the soil, cultivate the lower stuff, and then add new potting mix. The old stuff can go on the compost pile or just spread it on garden beds, which gobble up the stuff.  

I never got around to moving the Japanese Painted ferns last fall. They have thrived but are now too big for their location. Can I divide them now or at least move them or will they be too stressed?

You can move them now, but be careful not to damage the buds in the crown. One way to treat divisions gently is to lift the whole clump and then gently hose all the mud off the crown and the roots, and proceed from there. 

I desperately want to plant some fruit trees (peach, lemon) in my new yard, but the backyard is very shady because it backs up to wooded land (not my property so I can't cull). Would it be odd to plant fruit trees in my front yard? I also want to plan a veggie garden, but may be able to do that in my side yard, which gets more sun than the back. Thanks!

There are wonderful small fruit trees that look ornamental. I find peach trees attractive, others may not, and you may need a partner for good fruit set. I would consider an Asian persimmon. Pretty and fruitful. Citrus is not hardy here. 

Hello professor, thank you for chatting with us today. The previous owner of my house planted zoysia grass in the front yard and I want to get rid of it and convert the entire front yard to garden space. Since the roots go deep and send runners out throughout the lawn, a sod cutter won't work, and Roundup will just kill the top growth but not the roots. I'm thinking about cutting it as low as possible and putting landscape fabric on top then about 6 inches of topsoil. Will that kill it? And is 6 inches of topsoil enough room for plants to root? Thanks for your advice!

I have never killed zoysia, not sure mowing it tight will hurt it that much and the landscape fabric may not be fully effective (and will look terrible). I love to garden organically but this may be a case where the best course is to spray with an herbicide registered for zoysia. Its residual effect will harm seed germination for a period afterward, something to consider. You don't say what you plant to put in its place, so it's hard to say if six inches will be enough. Sounds thin, and remember, that it will settle to about half that thickness by the end of the year. 

Yay! A gardening chat! Woohoo! Now that I've got that out of the way, I am hoping you can help me. I live in a rowhouse with a front garden about 20'x10', facing west. About 10 years ago I dug up all the English ivy and planted 300+ daffodils and 50 daylilies. I added some periwinkle as cover to help with the weeds. The number of blooms has decreased over the years. Is it time to dig the whole thing up and replant? How do I do that with the periwinkle cover? Help and thank you!

The daylilies should be lifted and divided. The best time for this is September, but you might get away with it now. Again use the water method to de-mud the clumps and pry them apart with your hands, not a knife. One way to revive daffodil clumps is to give them a little balanced bulb food now.

I wanted to make you aware of an emerging problem concerning Preen and some of the bulb species, in my case the classic King Alfred daffodil. I had resorted to Preening my flower beds because I was not able to keep up with all the manual weeding in the last few years (I returned to college) but after planting 500 of the King Alfred daffodils, along with smaller amounts of other bulbs 3 falls ago,I only had about 10 bulbs of the King Alfred return last spring after the first years flowering. I did some research and discovered that this is becoming an issue for others as well. So it is to the corn gluten I go, even though I'm concerned with the extra nitrogen so early in the season. I'll keep you updated with it's success.

OK thank you. I don't use Preen because I have seeds I want to germinate, namely poppies, larkspur, etc. 

Hello, I am a novice at gardening. I planted some raspberries last year (a gift from a friend) and didn't get any fruit. They are taking up quite a bit of space in my limited garden area. Is it possible to move them to containers, or to another place in the yard? Should I just give up on them entirely? Thank you.

The problem with raspberries is that they bear well for three or four years and then fall off, either because they haven't been pruned properly or they contract a virus. It is much better with brambles to start with fresh, virus free stock.

Hi Adrian, We just had this question come up in our Master Gardener class this week. Because Potting Mix is not really soil, it doesn't hold all the goodies soil contains, though it lets the water drain easily. The recommendation was to change out the mix about every three years.

OK thank you. I do it every year but maybe I'm wasting money. One worry is that if you use synthetic fertilizers you will have a build up of salts that are ultimately not good for plants. 

I'm thinking about planting a couple of these fruit trees this year. Any suggestions? We are on a mountain slope but understand they will tolerate dry conditions.

Paw paws would be perfect, and the fruit is delicious. I think you need two for fertilization. Check out Edible Landscaping in Afton, Va. http://ediblelandscaping.com/buyPlants.php  

We have lots of underground water in our area of Howard County, and lately our sump pumps are going non-stop. I know that bald cypress can live in Maryland and transpire hundreds of gallons of water a day, but does bald cypress have the disadvantage that weeping willow does, that of sending roots into water pipes? Would planting a bald cypress in a strategic spot be a good idea? We have a large rain garden but it's getting overwhelmed.

I think bald cypresses would not be as invasive, rootwise, as willow. Other options would be a sycamore, a black gum and a swamp white oak.

I've built up some raised beds to take advantage of the one sunny area in our backyard. I had high hopes of doing a lasagna-bed, filling them with compost and leaf mold and creating the perfect soil. Except that real life got in the way and instead we just used the dirt we'd removed from the area where we're building a patio. It's not horribly clay-ey, and I did mix a little leaf mold in there, but it will certainly need to be amended. My question is, what would be the best material(s) to throw in now, before I start putting out seedlings? Many thanks!

I still use bales of peat moss, but that's becoming politically uncorrect. I'd love to hear from folks about whether they have stopped using peat moss and what they might use instead. I would add more leafmold (cheap from your local government at this time of year) and I like to throw in some sand. 

we have a back yard that we have no idea what to do with! we clear it out every year but then have no clue how to utilize it. It's a big space that's just wasting away. Who to talk to about fixing it up or landscaping? We're not the gardening types but even we admit something needs to be done!

I'm a big fan of the patio garden, and, if you need to, free yourself from the rest of the landscape by planting shrubs en masse. I will be exploring this and related topics in next week's Local Living section. 

Hi Adrian, Missed your chats, are they back for good? Wanted to know what you'd suggest for a small front yard shade tree in front of a town house. This is for a friend and I haven't yet seen their property, but wanted to give them some suggestions. I believe it is full sun. Thanx. Vienna, VA

They will be regular through the growing season! A shade tree, by definition, is big, but if you want a small, handsome tree, I would consider a redbud, an upright Japanese maple, a flowering cherry such as Dream Catcher, an improved variety of crab apple, an Asian persimmon, or a paperbark maple. I don't know that the world needs another Natchez crape myrtle. 

Hi Adrian - how about that snow this week? I had daffodils (in bloom) sticking out of the 4" we got. Anyway, my sister is living with me now, and has a very large, very wild chocolate lab. I have a porch on the back of my house that is open, with stairs in the center, and I have gardens on either side of the steps. Her dog doesn't go up the steps - instead runs through the garden and jumps up to the porch, which has destroyed everything I've planted there. Until she gets the dog trained (fingers crossed there), do you have any suggestions for some shrubs I can plant that can maybe deter her or at least stand up to being run into all the time? (I'm tempted to plant huge roses with thorns, but that just seems mean...).

No shrub would fix that behavior, I'd say. I would install low, picket fencing along the areas that the dog is using. Happily, the snow flattened daffodils are now up and perky.

I have a small container garden that I'd like to be both useful and pretty. Any ideas for some good edibles that are easy on the eyes? Maybe flowering?

I grew some lovely sweet peppers last year that looked stunning, I would consider bull's horn, Marconi, Costa Rican and Sweet Banana. 

I thought that raspberries, at least some cultivars, only bear fruit on the 2nd year canes. If she planted first year canes last year, they should bear fruit this year.

Classic varieties fruit on canes that grow on one year old wood, but new varieties such as Heritage fruit on new wood and can be cut back hard each year. 

...because you'll need to explain to me why peat moss is politically incorrect. Please.

Because it is harvested from peat bogs (in Canada and Northern Europe). 

Hi there - with the extended cold weather in the DC metro area, I just had to ask: I planted veggie seeds into a bunch of trays at the beginning of February (too early, I know) and have managed to grow over 140 seedlings (herbs, peppers, and tomatoes). As of right now, they are getting bigger and have nowhere to go as it's too cold outside. What should I do? Start all over again? I do have a few spare rooms with plenty of light.

Moral: Don't start warm season veggies too soon. You shouldn't put out tomatoes and peppers for another month, I'd say. You could try to keep them going under lights (close so they don't stretch). I would also start a new batch. Another option might be to build a cold frame, but that's a lot of work, and more suited to seedlings than bigger transplants. Suggestions anyone?

 

I get a load of manure in the fall and let it cold compost over the winter. I then amend my garden soil with that in the spring.

Sounds good. It takes about six months of passive composting to get good stuff, though it may still be weedy.

I have a heavy, rectangular planter next to my front door in which I put small boxwoods in the winder and caladiums in the summer. Sadly (it was a last gift from my late grandmother 20 years ago), freezing and thawing have finally taken their toll and it has begun to crack. Is there any way to save it?

Once a terracotta pot has cracked, I don't see it coming back. You could try some epoxy glue but I don't hold out much hope. If clay pots are emptied of soil and kept in a dry location, such as a shed or a garage, they will survive freezing temperatures. It's the moisture that dooms them. 

From an indoor plants class I took in college, every few years you are supposed to thoroughly soak the potting mix and let the water keep running. This will remove any salts that might have built up. Following that, you can add back fertilizer, compost tea etc to add the nutrients back to the potting mix.

My feeling is that containers are by nature in a prominent place, the plants need all the help they can get, and trying to re-use old growing medium is a false economy. Just splurge on fresh potting mix (or make your own with screened compost, sand, peat moss and perlite). Isn't this what spring is all about, messing with fresh soil? Pampering your little plants?

I set my early seedling containers in a wheelbarrow, then wheel the barrow outdoors on warmer mornings and bring them in at night between now and planting time. It's a gentle way to "harden them off."

A great idea. One thing to think about when hardening off: If it rains, the pots may be sitting in a tray and get saturated. You have to lift out the pots, dump out the water, and set them back. Bit of a chore, but necessary. 

Can you plant a few leafy greens around the edges for decoration as well as spring salad? I find that Buttercrunch and Red Sails and the slowest to bolt.

Absolutely. Other pretty greens for pots: red mustard, Bull's Blood beet, and Swiss chard. 

I'm looking for a web source that shows the different growing zones or regions and describes when gardens can be planted. This year will be our first gardening year in Idaho. Which sources do you recommend? Thank you!

http://planthardiness.ars.usda.gov/PHZMWeb/

Here's the USDA plant hardiness zone map. You can plug in your zip code and get your (general) winter conditions and plant accordingly. I would check with your local county extension office for last (and first) frost dates. 

Novice gardener here. The house we bought a year and a half ago has planted beds. Last spring, a couple of beds had these really pretty lillies through them. They were orange and maybe a foot or eighteen inches tall. Way smaller than tiger lillies, but I don't know what they were. This year, only about 25% of them have come up. Could the weather have affected them, or is it time to replant. If I need to restock them, when and how (seeds, bulbs, spring, fall?) should I do this. Thank you. My goal is to at leasst keep my yard from looking worse until I learn how to make it even better.

Might be martagon lilies, which are pretty things but on the margins here because of our hot climate. I like big OrienPet lilies. You could order and plant lots of lilies now for a great show this summer.

This has me thinking, what to do about existing potted plants? I have a houseplant (a large palm) that has literally been growing in the same soil for years, but I have no idea how to change out the soil without damaging the roots.

Now is the moment to re-pot house plants. Get a pot that is two inches bigger in diameter, pull out the old plant, and, if pot bound, score the roots, tease them out, and snip them a little with scissors. I would soak the whole plant in warm water with a touch of bleach added to kill mealybugs. And did I mention? Get new potting soil.

OP here: So what happens to the peat bogs after the peat moss is harvested? Don't they make new peat?

The argument is that it takes several hundred years to replenish what the machine has harvested. Anyway, time to get back to it. This cold will break soon, and we will yearn for it to return. Believe me. See you soon.

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Adrian Higgins
Adrian Higgins is The Washington Post's gardening columnist. Read his recent story on lawn mower repair and follow him on Twitter.
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