April in a Connecticut Rose Garden

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In Connecticut, April is the month rosarians can typically open their gardens!!

Caution! Connecticut rosarians have to be patient, because there is a tendency to want to open our garden as soon as the snow is gone, and warmer days are upon us. However, because we know that we can still get severe cold here into the first of May, we try to keep to the following schedule to complete our early season tasks.

In April (when the forsythia blooms) we can begin the pruning of our shrubs and climbers. Our goal is to thin and shape these larger plants in an effort to get a desired bloom display, as well as to keep these vigorous growers from getting out of hand by the end of the growing season. We will remove dead, and older canes as necessary to get the desired result. We will also prune to effect a “dome of bloom” presentation on our repeating shrubs such as “Knockout” and “Bonica”. We will train our climbers along their various supporting structures. On the other hand, our OGRs are left to bloom, and will be pruned later (August-October) for next year’s desired result.

Early April is also a good time to do soil testing. This can be done by the Connecticut Agricultural Extension stations in New Haven or Windsor, or the UCONN facilities. The desired pH of around 6.5 is best for facilitating the availability of nutrients to the plant’s roots from the soil, and the fertilizers that we will be applying during the growing season. If low (<6.0), and application of lime, as described in the Soil Testing report, will help to raise the pH during the growing season. It is also desirable to know the potassium and phosphorus concentrations, because they may be good already, and we don’t want to use fertilizers that will add significant amounts of these if they are not needed i.e., use a 10-6-4 formulation instead of a 10-10-10.

Planting of bare root roses can be done as soon as the weather and soil conditions permit. Remember to dig a sufficiently large hole, amend the soil appropriately with plenty of organics (10%-25%), and most importantly mound the new plant canes with soil until growth appears, meaning that the plant is taking up water and nutrients through it’s roots. Also, protect the new growth from the hot mid day sun when first uncovering it until it has adapted (“hardened”) to the day’s light. This is also true when uncovering winter protected plants.

In mid April begin to remove winter protection if the ground has thawed. We don’t want to do this too early, which would allow the ground to thaw to quickly and heave. This may cause feeder root damage. We may have opened our Kones (plastic foam coverings) already (when day time temperatures reached into the 40’s) to ensure good ventilation as the late winter mid day sun is very warm even though the air temperature may not be. We do not want radiant heat to build up in a closed Kone, and burn the plants. Begin removing the mounding material, and covers such as Kones, when the buds begin to swell (indicative of sufficient soil warmth to ensure the ground frost is gone). Use a hose sprayer to carefully wash the mounding material away from the bud union. Additionally, be sure to clean the beds thoroughly of all remaining debris as rose pests of all kinds can winter over in this material.

Mid April, final pruning of the remainder of the rose varieties (HTs, florabundas, minis, etc.) can begin. Remember that pruning stimulates growth, so holding off if it is still very cold may prevent damage to the new growth due to exposure to hard freezes. Also, the exhibitor prunes on a much more planned schedule in an attempt to coax the peak bloom towards the exhibition dates. Remember that, once we prune, and stimulate the plants, we are now at risk of damage to the new growth if severe cold returns. We hope for the best, but know we live in Connecticut! There may be some rose disease considerations in late April. A lime/sulfur application according to directions may be done early in the month as a preventative measure. A fungicide spray program according to directions may commence later in the month if significant new growth has begun, also as a preventative. We use a systemic fungicide at this time.

 

And something that has reared its head in the past decade in particular: midge.  These tiny pests have a short life cycle, but each generation bites and kills small buds of roses so they won't bloom, and then the well-fed adult drops to the ground and burrows down and procreates. Little time is really spent above ground, so the solution to control is to apply complete insect killer to the ground several times each year (about monthly) starting in late April.  

Finally, a feeding program can be considered during the later part of April. If we decide to, we will use a liquid fertilizer as a “wake up call”, because the ground temperature is still too cold for granular fertilizers to have the desired effect. Generally consider granular fertilizer (10-10-10) around the beginning of May.