Category Archives: Propagating & Pruning

propagation & pruning

Growing Biennial Angelica

One of the stars of our late summer pollinator garden is Angelica, whose umbels of tiny flowers invite insect and butterfly activity galore.  Angelica are biennials, and most of you know this  means that seed sown this year grow roots and foliage, with flowers appearing in year two. The hope is that once planted, the Angelica will self sow, providing progeny for years to come. Hmm, sounds good, but….

Angelica germinates best after the seed has been exposed to cold temperatures. If plants are allowed to self sow in the garden, the seed naturally gets a long winter chill, and wakes up with the spring rains. When this works, it’s wonderful! In our experience this is not always something to be counted on. What if the seed germinates but then a dry spell settles in and you are too busy to observe and water?

We choose not leave our supply up to chance. After collecting seed in the fall, we store it envelopes in a cool dry space. In February we sow the seed in a slightly dampened germinating mix and let it sit for 2 weeks at room temperature (60-72F). We then transfer the seed flat, enclosed with a sealed baggie, into the refrigerator (35-40F) for 4-6 weeks (you could also try leaving the flat in a safe spot outdoors). In April, we transfer the seed flat out to germinate under 60-70F conditions. Once the seedlings have developed first true leaves, we transplant them into deep 2” tubes (Angelica do develop a taproot). When plants are established enough they can be transplanted into the garden, or in our case, into deep nursery quart pots for retail sales.

Angelica atropurpurea

There are numerous species; here are a few of our favorites. Angelica gigas, native to Korea has bolder foliage with dense deep wine globular umbels. Angelica stricta ‘Purpurea’. (aka A. sylvestris purpurea) hails from northern Europe and has dark tinted stems and foliage, with 4’ stems bearing dark purple flower buds opening maturing to lavender-pink, followed by attractive seed heads. There is a species native to parts of the US, including New England, Angelica atropurpurea, (Purple angelica) which has medicinal uses, plus it is quite ornamental with tall  red tinted stems and green to white umbels.

If you want to grow Angelica in large swaths of your garden, why not order seed and sow this winter. You’ll have to wait a year for blossoms, but you’ll have dozens of plants. Or, compromise. Purchase a few established first year plants and get them in the ground this year for color and activity next, but still sow seed next winter for your endless supply.

Buy online

Demystifying Seed Collecting: Harvesting, Storing and Sharing

nasturtium babies

nasturtium babies

It started with a nasturtium seed in a paper cup. Oh so many years ago, my first grade teacher instructed her classroom of 6-year olds how to plant the round nubby seeds. Within a week or 2, the first beautiful leaves broke through the soil. I have been smitten with germination ever since.

Many folks sow their are own annual seeds, but not so many give perennials a try. It is important to note that in recent years seed sown perennial selections have dwindled at garden centers.  Wholesale suppliers now favor the patented sterile clones that some say boast more uniform growth. (Hey control freak gardeners, it’s time to let go of that! )

honeybee on a single white Chrysanthemum

Upon becoming a beekeeper 5 years ago, I got a wake up call that seed-grown perennials provided more pollen and nectar, which in turn nourish our honey and native bees.  Our plant selections now include many more seed sown strains of perennials, shrubs and even trees, and this is the trend we foresee for other small specialty growers.

This brings me back to the importance of this topic:  seed collecting. Here are more reasons to encourage you to  harvest your own seed.

  1. To be able to propagate more plants for new garden beds
  2. To preserve strains that you find remarkable
  3. To be economical  (seeds are getting expensive)
  4. To participate in seed exchanges.  One benefit of joining various plant organizations such as the Hardy Plant Society or the North American Rock Garden Society is you have access to their seed exchanges. Share your seed with other members, and get access to many varieties not found at the local garden center.

peonies…the blue fruit are the ones that have fertile seeds

The first question many first time seed collectors ask is when should they harvest seed. This varies from plant to plant. You do need to collect seed as soon at it ripens, before the pods or capsules burst and dispense. Seed ripens at different times on different plants throughout the year so you need to pay close watch. Spring bloomers like Primrose and Vernal Sweet Pea ripen in June and early July, while on a late August day, the pods of species peonies burst to expose their bright red and blue fruit (the blue seeds are the fertile ones). Bluestar seed pods are ready to collect in early September, while it may be late October before you can harvest seeds of Compass Plant.

Our changing climate will challenge any timing rules. However, I just came across a website which may be of great help  the Seed Site .  It has a wealth of information on what pods and ripened seed look like on hundreds of different plant species.

Clockwise from top left: Cynara cardunculus, Galtonia viridiflora, Talinum paniculatum

Once you collect your seed, you should clean off the chaff and store in a cool dry spot in paper or glassine envelopes.  Make sure there are no tiny insect pests hanging out in the capsules. Some seed, such as Arisaema (Jack in the Pulpits) and Hellebores benefit by being stored enclosed in a moist paper towel inside a baggy, and kept in the refrigerator until spring.  Remember to label right away. You think you’ll remember, but…

The proper time for sowing and seed treatments differ depending on the plant. There is no one source that has complete information, but we often refer to the Jelitto Seed Website for germination tips. 

I encourage you to save your own seed. Yes, there is always more to learn,  but once you start you will gain confidence.  Go outside now and see whether you have a windfall of seed ready for harvesting.

Tip: It’s time to pinch!


Chrysanthemum ‘October Glory’

You may have already done this, but if not, now is  the time. In order to encourage many more  flowering shoots from perennial Chrysanthemums, pinch back stems to 4-6″ at the beginning of July. This encourages more stems to shoot resulting in many more blossoms, and perhaps tidier plants. (Of course, if you prefer the blousy look of tall stems that billow forth, by all means leave your plants be.)


On the left are a few budded shoots but there could have been many more…on the right, ‘Hannah’s Double White’ with numerous blossoms.

You can also cut back the taller fall Asters and their relatives, such as Boltonia, to keep them neater and in proportion to their surrounding neighbors. For example, Aster ‘Vasterival’ reached 5′ last September, and it was just too much Aster for the nearby Caryopteris and perennial mums.


Tall willowy stems of Aster ‘Vasterival’ before cut back, and in flower.

Spring Succulent Rehab


Remember your gorgeous succulent containers from last summer? Did you take the time to bring in and care for all those tender
plants over the winter? And, now, do they look overgrown and leggy, or a little scruffy to say the least? You have company…mine do too! Here are some suggestions on what to do to give these babies a new lease on life.


Give your succulents some fresh soil!

First, give your succulents some fresh soil for new roots to grab into. Remember to use a sharp draining mix formulated for succulents…a basic everyday potting soil will stay too moist. Loosen up the roots, and shake off some of the old soil. Remove any old browning leaves that still cling to the lower stem. Repot in the same pot or a pot that is slightly larger.

If you are rehabbing a large container of mixed succulents that were part of an ensemble and want to give it new life, unplant everything and do the same thing. You can top dress the soil with a fine gravel, chicken grit or uncolored aquarium sand, which will prevent low lying foliage from staying in constant contact with moist soil.

Rosette forming succulents often elongate during short winter days and low indoor light, or they may just be prone to doing so anyway, with age. You might like to have the height that tall gangly stem offers, and if so, just leave the plant be. On the other hand you may want to offset the top heaviness. There are a couple of options.


Aeonium with aerial roots….

Option 1:  Bury Her. Notice that a lot of bracing aerial roots have developed along the stem of this Aeonium ‘Cyclops’. Last year I tried this unorthodox remedy. I found a deep clay container and replanted the Aeonium low in the pot. Succulent soil mix was used  in the lower half, but then I topped the upper pot portion with perlite. This allowed good aeration for new roots to develop off the main stem.


Option 2: Off with her head! This may cause you to hesitate, but you will have to cut off the  Aeonium’s top rosette, (you can then root the rosette to form a new plant).  The stalk will hopefully break anew with fresh growth and branch out, but I should warn you this takes a while to happen.  As for that top rosette, let the cut edge air dry for a few days to “heel” or callous over. Then fill an appropriate sized pot with perlite or a mix of perlite and sand, insert the cut end of the rosette into the pot and water frequently.


Echeveria with elongated stem

These methods work for elongated Echeveria too. Repot in a tall tom, or cut off the top rosette and try rooting it. Note: You may or may not be able to encourage side rosettes off that main stalk (depends on what type of Echeveria hybrid it is), but hopefully your rosette will root in to form a new plant.

Mystery Echeveria…purchased as 'Fleur Blanc'

Echeveria ‘Fleur Blanc’

Many succulents bloom in late winter and early spring, and these blooms are quite lovely, as seen above in Echeveria ‘Fleur Blanc’. The blooms often help identify plants that you may have acquired without a proper name.

xsedeveria_mixup (1 of 1)

Look-alikes. x Sedeveria ‘Letitia’ on the left, and ‘Sleepy’ on the right.

For example, these two very similar x Sedeveria are often mixed up in the nursery trade. When not in bloom they do look quite alike.  Now in flower, I can tell that the one on the left is Sedeveria ‘Letitia’ (pale yellow/white) and on the right is Sedeveria ‘Sleepy’ (orange/yellow). Also, notice some plants like these Sedeveria have offsets forming at their base. These offsets can be severed and rooted or potted in small pots if roots have already formed.


Cuttings left to heel, decayed foliage must go, leaves sometimes root too!


  • Cut back leggy growth.
  • Let cuttings air dry for a few days to seal the cut ends.
  • Lie or stick in a sand/perlite rooting media.
  • Groom aging  and decaying foliage.
  • Repot all plants in fresh succulent potting soil to give them a new lease on life.
  • Top dress newly potted succulents with fine gravel, aquarium stone, or chicken grit
  • Note (and photograph if you can) what the flowers look like on your plants to confirm their identity.

With longer days and fresh soil, your repotted succulents will show you how happy they are in 4-6 weeks. Once the weather warms, transition plants outdoors on mild days, first in a spot which has just morning sun, and then gradually allow them full day light. Too much strong sunlight on a warm day after plants have been indoors may cause the leaves to get sunburned.

For other posts on Spring Care of Succulents see:

In bloom: Tender Succulents

Rehabbing Succulent Containers





Collecting Seed for Seed Exchanges

Clockwise from top left: Cynara cardunculus, Galtonia viridiflora, Talinum paniculatum

Clockwise from top left: Cynara cardunculus, Galtonia viridiflora, Talinum paniculatum

A few of the various Plant Societies which I belong to have seed exchanges, and I made a pledge to myself to get my seed collecting done, cleaned, sorted and packaged into little envelopes to meet this year’s deadline, which is usually Nov 1.  Time always has a way of getting ahead of you, so I was relieved to learn on the Hardy Plant Society’s webpage that they have extended the deadline this year to Nov 15, and I can fill out the donation forms online and mail the seed in later! The North American Rock Garden Society is not being so lenient; they want the list of seed being donated by Nov 1st, although they will allow a grace period until Dec 1st to package and send your seed in.

Yes, it does take time to process and save seed, but let me tell you why it is worth all the trouble. First, if you want to grow more of the plants, especially the annuals, which you enjoyed in your garden this year, why not collect the seed and save yourself a few dollars. Second, you may not be able to find a particular seed variety next year. I have found this true when it is an unusual variety that commercial growers do in limited numbers, or more likely their source dried up or had a crop failure. Third, you are bound to collect more seed that you can use, so why not share the bounty by participating in a seed exchange? Most seed exchanges work this way: You become a member of the group, such as the Hardy Plant Society, which collects and pools the seed, then makes the seed available to its membership at a very inexpensive price ($.50). A big plus: seed donors get first dibs at the selection,  and get to select an extra 10 packets for their efforts. Groups like the Seed Savers Exchange allow you to purchase seed without becoming a member, but membership has its perks….lots of information, discounts and member’s only offerings, plus you’re supporting an important organization.

There’s a lot to know about collecting seed, but it is beyond the scope of this blog post to get into a lot of detail.  Besides, there is so much information now on the internet that you no doubt will find answers to particular seed questions in a web search. I just want to pass on some basic tips.

  • Collect seed on a sunny dry day. Wet seed pods can harbor spores which may encourage mold and spoil the seed.
  • Label your seed correctly, especially if you plan to donate to a seed exchange.
  • If you grow several varieties of certain plants and they are within close range of each other (for example: several different forms/colors of zinnias) your seed will not come true to type. You may get some interesting variations and colors, but you should label it as such. Also, seeds from most F1 Hybrids will not come true.
  • Watch seed pods daily for maturity. You want to capture them just before they explode all over your garden.
  • Store the seed in paper bags in a dry spot until you have time to clean and sort.
  • Separate the chaff from the seed when packaging.

Here are  links for more information on joining a few Plant Societies.

The Hardy Plant Society–Mid Atlantic Group

The Hardy Plant Society–UK

North American Rock Garden Society

The Seed Savers Exchange

A Dreaded Chore: Repotting an Agave

sad, sad Agave

I’ll confess. I had avoided repotting (for almost a year now) what had become one very sad looking Agave.  The older leaves had become brown and ugly, and obnoxious weeds had taken root. The piercing tips and teeth on the leaves looked ferocious, and I didn’t want to give blood. So there it sat, in a neglected corner, a woeful sight indeed.

As we were gathering all the tender plants to bring inside for the winter, it was time to make a choice about whether to save or toss the misbegotten Agave. A decision was made: yes, save it. A plant that has the will to carry on despite such neglect deserves not only respect; it deserves admiration. And as it turned out, grooming and repotting wasn’t a big deal after all. Here’s how we went about it:

The first thing to do is put on some protective gloves. Carefully remove the Agave from its pot, standing over a wheelbarrow or large receptacle to catch the debris. Tilt the plant so you can get at the base of the crown with your clippers and remove the dried up foliage. Next, loosen up the soil around the roots and remove any weeds that may have established, teasing out their roots so they won’t make a comeback.

Use a very well drained soil mix amended with sand and perlite, and if you have access to grit or gravel, add some too. (We don’t add fertilizer, since Agave are very light feeders. Instead, we liquid feed with fish emuslion/seaweed 2 or 3 times a year.) Position the Agave in the center of the pot, and then backfill. The repotting is accomplished, and we can now place the Agave in a spot where it merits attention.

carefully remove old leaves

loosening the roots

Agave, happier looking now


Weeping with Wisteria…

Wisteria floribunda 'Blue Eyes'It’s the third week in May, and the Wisteria floribunda ‘Blue Eyes’ which covers our pergola has begun to drip with fragrant blossoms. It’s certainly a sight, and elicits ooh’s and ahh’s from nursery visitors. Conversation immediately turns to pruning advice, and the question we hear over and over again, “Why hasn’t my Wisteria ever bloomed?”

We’ll cover extensive pruning Wisteria advice in a later blog posting, but let me address the flowering question. Wisteria often take several years to bloom after transplanting as it  is concentrating energy on establishing a firm root system, but there are other points to consider. First, plants should receive a good 6 hours or more of sunlight. Also, do not fertilize with a high nitrogen fertilizer. Wisteria are in the legume family, and fix their own nitrogen from soil. Select a fertilizer with a high phosphorus # (the middle number) such as 5-10-10, 5-10-5, or  Espoma’s FlowerTone which is a 3-4-5.

It is advisable to select named clones which have been propagated from productive flowering stock. Wisteria grown from seed are quite variable in their blossom production, and some have been known to never produce a bud. Another thing to consider is that Wisteria sets buds on old wood, and should be pruned  in late spring after flowering (or when it should have flowered) to about 6″ from main branches. One other trick is root pruning in early spring. Using a sharp a spade, dig in about a 2′ radius from the base of the vine. This will sever the roots and may shock the plants into flowering.

Pruning 301

This is the third in a series of blogs preceding our upcoming pruning workshop.  Today we’ll examine growth habits and regenerative responses.  Make the most of our upcoming workshop but reading through this series of blogs first.  For questions, address Chris @
 Let’s review each of our five plant categories:
Chamaecyparis o. 'Fernspray'

Semi-open Form Conifer

Deciduous Conifers– This group produces a central leader. A central leader is a single trunk headed straight up to the sky. Structurally, this is the best of all growth habits.  It is pretty much impossible to prune them into any other form; they will always revert to a single leader. Their branching is symmetrical. This group regenerates well because of the dormant buds present throughout the trunk (old wood).

Evergreen Conifers– Of the tree forms, some naturally produce a central leader while others produce multiple leaders.  Most can be trained to a central leader if you have the patience and start training them in their youth.  Multiple leaders have the tendency to spread apart under snow and wind loads.  This group does not regenerate well because dormant buds are not present on old wood. Small shrubs forms of evergreen conifers will be addressed in the workshop.


Closed Form…Boxwood

Broad Leaf Evergreens- Most are multi-stemmed  and should be left that way. These produce many stems from the base as well as many primary, secondary and tertiary branches.  This group regenerates well; they will sprout from old wood, when damaged or presented with more sunlight as dormant buds exist throughout.

Clethra barbinervis form

Open Form of Deciduous Shrub/Tree

Deciduous Trees-Some naturally produce a central leader while others produce multiple leaders.  Most can be trained to a central leader if you have the patience and start training them in their youth.  Although snow and wind loads are not as detrimental to this group, they have greater stuctural integrity as single leader specimens.  Most have strong regenerative response to pruning, damage and increased light exposure.

Deciduous Shrubs-Most are multi-stemmed  and should be left that way. These have strong regenerative properties and can be cut back as far as you’d like (if you don?t mind foregoing a years blossoms).

In general, Alternate branching plants are easier to prune into “open forms” by a process called thinning out (think apple trees in an orchard or well-tended Tea Roses), but don’t respond as well to  extensive tipping back (shearing), which produces that scrumptious chicken croquette shape.  The exception to this occurs when the alternate branching pattern has short internodal spacing (the distance between one branch and the next is very short). Many evergreens such as boxwood, yews, and arborvitae produce closed forms without any help from shears because of their short internodal spacing. Opposite branching plants generally take more work to prune into open forms, but in many instances it is worth the effort.   This branching habit tends to produce  a “closed form” and shearing only intensifies this, often resulting in the “cartoon strong man form”, all upper body with skinny little legs.

Pruning Basics: 201

This is the second in a series of blog posts leading up to our April 17, 2011 pruning workshop.  These posts will address things you should be familiar with before you take pruners to plants.  If you’ve signed up for the workshop, we encourage you to read through blog posts.

In the blog entry Pruning 101,  you were asked to identify the plants you are intersted in pruning.  With plant names now in hand, you next need  to decide which of the following woody plant groups your tree/shrub falls under.

Opposite Branching

  • Conifers deciduous e. g.  Larix (Larch), Metasequoia (Dawn Redwood), Taxodium (Bald Pond Cypress)
  • Conifersevergreen e. g. Pinus (Pine), Picea (Spruce) Abies (Fir)
  • Broad Leaf Evergreen e. g. Rhododendron, Ilex (Holly), Pieris (Andromeda)
  • Deciduous Tree e. g. Acer (maple), Quercus (Oak), Stewartia, Fagus (Beech)
  • Deciduous Shrub e. g. Rosa (Rose), Viburnum, Salix (Willow), Spirea, Vaccinium (Blueberry), Lavandula (Lavender)

These 5 groups are your launching off point: each embodies of group of plants that generally have specific growth/branching habits and regenerative responses/capabilities.  We will leave the regenerative processes for the next blog.

alternate branches

Alternate Branches

Growth and branching habits are responsible for growth patterns in all plants and they fall under one of two groups,  alternate or oppositeAlternate branching occurs when only one new shoot/leaf node develops along a plant limb at any given point while the next developing shoot/leaf node occurs at a different point on the opposite side of the limb-see example. Opposite branching occurs when two new shoots/ leaf nodes develop at the same point along a limb, but on opposite sides of the limb-see example.  Although the examples here are clear, it is often less so because there can be a considerable amount of variation.  Make an attempt to differentiate these patterns on your own plants, while noting their variability.  We will examine what this variability means to the pruning process when regenerative responses are discussed in the next posting.



Pruning Basics 101

This will be the first in a series of blogs leading up to our April 17, 2011 pruning workshop. That stated, this article will help everyone on there way to pruning, even if they can?t join in the fun on April 17th. These blog posts will address things you should be familiar with before you take pruners to plants.  Make the most of our upcoming workshop by reading through thisseries of  blog posts. For questions, address Chris at

Styrax japonica in winter

Every plant has a name, both Latin and common. For a beginner, knowing one or the other is crucial. If you don’t know either, then it’s impossible for any professional to tell you how to prune it. Photographs will help to identify it. Let’s assume it is the off seasons, late fall through early spring, when all our deciduous plants are posing unclothed, their bare limbs shivering. You will snap 2 or 3 photos: one of the entire plant, and one of an individual 8 -12″ section of an outer limb, and perhaps one of the trunk or base of the plant.  If you think that the bark or the terminal buds (the very end of the branches) is unique, than snap a photo of that too. Make notes about anything you recall it doing in the previous year, e. g. “It bloomed white on Mother’s Day” or “the fall color was butter yellow”.  Send this information to Avant Gardens (or a good local nursery) via email and we’ll help you out (you might want to reference this blog to let us know you’re not sending spam; we get nervous opening up attachments from senders we don”t know). Don’t be shy. People in the plant trade love to share information!

If the growing season has begun and  plants have leafed out, take three photographs: one of the whole plant, one of the plant in flower (if it does bloom), and one showing a small segment of branch with leaves attached. Does your plant has some other distinction, like mottled bark, unique cones, columnar habit, scent, etc? Snap that picture or make  notate these observations.  Make note of anything you remember about that plant that will help identify it. ( A note that your mother-in-law gave it to you probably won’t aid in identifying it, unless of course she remembers what it is– and it is not a problem to ask her. )  Remember that you can always ask us at Avant Gardens or check your local nursery.

Examples of helpful shots are:

Styrax bark

Chamaecyparis obtusa ‘Fernleaf Gold’

Chamaecyparis branch